15. GAS SAFETY...........................................................................................................90 16. PRESSURE SYSTEMS AND VESSELS.................................................................95 17. MISCELLANEOUS PRACTICAL ASPECTS...........................................................99
17.1 Glassware and Sharps.................................................................................99 17.2 Rubber and Plastic Tubing...........................................................................99 17.3 Oil Baths.......................................................................................................99 17.4 Low Temperature Baths.............................................................................100 17.5 Lifting Equipment........................................................................................100 17.6 Ladders.......................................................................................................100 17.7 Fume Cupboards, MSCs and other Containment Devices.........................101
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12. CHEMICAL SAFETY INFORMATION AND GUIDELINES
The information contained within this Section and associated guidance applies to the handling, use, storage and disposal of hazardous substances and aims to prevent, or where that is not possible or is not reasonably practicable, to minimise the risk of harm or adverse effects and to set appropriate standards for the control of residual risk arising from work with hazardous substances.
12.1 Hazardous Substance Risk Assessments The Control of Substances Hazardous to Health (COSHH) Regulations and the Dangerous Substances and Explosive Atmospheres Regulations (DSEAR) require that a suitable and sufficient assessment of the risks to health and other dangers such as fire and explosion, created by work involving these substances, be made prior to the commencement of the work. Consequently, hazardous substance risk assessments which address the hazards presented by substances must be carried out in advance of work commencing and the significant findings of the assessment must be recorded. Where people are likely to be affected by the work involving the substance(s) they must be informed of the results of the assessment.
Risks arising from activities involving hazardous substances must be eliminated or where this is not possible or practicable, the risk of exposure must be adequately controlled. Where control of exposure is achieved through engineering measures (e.g. by using fume cupboards) or items of personal protective equipment (PPE) (i.e. lab coat, safety glasses, gloves), appropriate information, instruction and training must be given in the proper use of the control measures.
The purpose of the assessment is to enable a valid decision to be made about what measures need to be taken to prevent, control or reduce exposure to hazardous substances, or to prevent dangerous situations from occurring or arising from the work activity.
It should be noted that every use of a substance that is hazardous to health or dangerous, i.e. the process/procedure, must be assessed, and as such certain factors need to be considered when making the assessment. These include:
1. The substance and its characteristics: All chemicals are toxic to living organisms under certain conditions. However, a highly toxic chemical will produce damage even in small amounts, whereas a substance of low toxicity is unlikely to produce any injury unless the exposure involves large quantities, or the accumulation of the substance through repeated exposure.
Liquids with a high flashpoint become dangerous when the work activity raises their temperature above the flashpoint. Dusts can form explosive atmospheres. The flammable nature of a substance, its potential to form an explosive atmosphere, the likelihood of thermal runaway, and the presence of ignition sources should also be taken into consideration.
2. The form in which the substance occurs (e.g. particulate, liquid, gas) because this influences the way in which the substance is presented to the body and hence the risk. Mixtures and preparations will also be encountered in addition to pure substances. The extent to which the properties of mixtures and preparations may differ from the properties of their individual component substances (e.g. solvents facilitating absorption through the skin) must be taken into account.
3. The exposure: The activity, method of production or use of a particular substance influences the quantity absorbed. Consequently, the number of exposures (i.e. single, repeated or continuous) and their duration, the intervals between exposures and the total length of exposure must be taken into consideration. Due consideration must also be given to the consequences of exposure and synergistic effects as a result of exposure to two or more substances at the same time or one after the other. Exposure due to any reasonably foreseeable deterioration in or failure of any control measure provided should also be considered.
4. The workplace. Consideration must be given for how and where the substance is used and under what conditions.
5. The individual’s own physical health and susceptibility to exposure.
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It is important that when undertaking an assessment of an activity involving hazardous substances that consideration is given to the hazardous nature of any products, by-products (including emissions) and waste products and residues, and that these are included in the overall assessment.
It is useful when undertaking an assessment that all of the following points are addressed:
1. Is it necessary to use the hazardous substance? Can a less harmful substance be used?
2. Will the process generate toxic intermediates, end-products and by-products?
3. Are hazardous substances present in sufficient quantity/concentration to cause a health risk? If so, which substances pose the significant risk?
4. How and in which form (e.g. liquid, gas, vapour, powder) are hazardous substances present or, likely to occur, and what are the intrinsic hazardous properties of the substance(s) (i.e. is the substance toxic, corrosive, an irritant, an oxidiser, flammable etc.)?
5. What harmful effects are possible (i.e. could the substance cause burns, respiratory problems, cancer etc.)?
6. What are the possible routes of exposure, i.e. skin, eyes, inhalation, ingestion, injection?
7. Under what circumstances could exposure occur under normal conditions of use (e.g. failure of extraction ventilation, spillage, breaches in procedures, mixing etc.)?
8. Does the substance(s) have a Workplace Exposure Limit?
9. Who could be exposed and how could exposure occur? Consider other workers within the laboratory or workplace, students, maintenance workers, contractors, cleaning staff, visitors etc.
10. How likely is it that harmful exposure will occur? Consider the concentration likely to be produced by the work concerned, the effort needed to do the work and the effect of any engineering measures and systems of work.
11. Are the existing control measures adequate, working effectively and checked routinely?
12. Are any additional measures warranted e.g. is mechanical ventilation or containment needed?
13. Is health surveillance required?
14. Are people who might be at risk from the harmful substance informed, instructed and trained on the nature of the risks, how to avoid the danger and what precautions are necessary? Do they know what action to take in the event of an emergency? Remember that the risks are also person specific. People that are immuno-compromised, sensitised to specific substances (e.g. glutaraldehyde), are pregnant or are a young person can be more at risk from a hazardous substance.
15. Is everyone involved in the activity confident in the adequacy of control measures and are they competent to use the control measures? Do they require further information, instruction and training?
Once these points have been addressed a decision can be made on the actions needed to prevent exposure or to reduce it as far as is reasonably practicable. This will also include the actions to be taken in an emergency, to clear up any spills and to safely dispose of any residues, wastes etc. The risk assessment process for a substance hazardous to health is summarised in Figures 6 and 7.
12.1.1 Sources of Safety Information In order to complete a hazardous substance risk assessment, detailed information is required pertaining to the hazardous properties of the substances being assessed. Suppliers’ labels, safety data sheets (SDS) and catalogues or data banks are the primary source of safety information. However, suppliers’ safety information describes the inherent properties of their product and regard must be given to the specific circumstances of use such as the quantity used, frequency of use, duration and location of use and any reaction or degradation products that might result.
Various web sites are available which contain basic SDSs for common substances. Please note that SDSs taken from a web page are only a guide and can often be out of date.
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SDSs may still include Risk and Safety Phrases (R and S numbers) which were replaced by Hazard and Precautionary Statements respectively in December 2010 as part of the United Nations Globally Harmonised System (GHS) (see Section 12.12, Safety Terminology).
12.1.2 Preventing or Controlling Exposure – The Hierarchy of Controls The COSHH Regulations require in the first instance, prevention of exposure to substances hazardous to health if it is reasonably practicable to do so. This might include:
• Changing the process or activity so that the hazardous substance isn’t needed or generated, i.e. it is eliminated.
• Substitution with a less toxic material/safer alternative (this is especially important if the substance is a carcinogen, mutagen or sensitiser).
• Use of the substance in a safer form e.g. pellets instead of powder, or a less concentrated solution.
However, if prevention of exposure as detailed above is not reasonably practicable, exposure by ALL routes must be controlled, i.e. inhalation, contact and absorption through the skin or mucous membranes, or by ingestion. Controls are likely to be set to meet the most hazardous properties of any substance in a process.
Figure 6: Assessing the use of a substance
Is exposure likely in this use?
Yes / Don’t know? No No further action
Yes Get information
Are effects serious?
Yes? No No further action
Can substance be eliminated?
No Yes Eliminate it
Are effects known?
Can substance be substituted?
No Yes Assess alternative
What are the properties of the
substance?
No / Don’t know?
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For substances which are classified as dangerous under the DSEAR Regulations, e.g. flammable substances, oxidisers and explosives, petrol, liquefied petroleum gas (LPG), paints, varnishes, solvents and certain types of dust that are explosive (e.g. wood dust), the following control measures must also be employed:
• Reduce the quantity of substance used to the absolute minimum required (where possible, the substance should be substituted with a non-hazardous alternative in the first instance).
• Avoid or minimise releases. Consideration should be given to ways of controlling releases at source.
• Prevent the formation of an explosive atmosphere by ensuring adequate ventilation and where necessary, employing the use of local exhaust ventilation.
• Collect, contain and remove any releases (e.g. by ventilation).
• Remove all sources of ignition. Where this is not possible, sources of ignition including electrostatic discharges should be avoided in the area where dangerous substances are used. Appropriate emergency equipment must be available at all times.
• Avoid adverse conditions (e.g. high temperatures where there is the risk of thermal runaway).
• Use systems of work which minimise the risk of fire and the likelihood of an explosive atmosphere from forming.
• Segregate all incompatible substances.
Figure 7: Controlling the risk from a substance *Note: PPE (clothing and eye protection) may need to be worn in all circumstances where hazardous substances are used
Control it
Can it be fully controlled? Yes
Separation Enclosure
LEV Fire & explosion
prevention
Maintain controls Check controls
Record checks and maintenance
No
Use safe systems of work (SSW) / safe operating procedures (SOPs)
Provide training in safe handling and emergency measures
May need health
surveillance
Respiratory protection Eye protection
Clothing Gloves Boots
Maintain Check
Record checks and maintenance
If substance cannot be substituted by a less hazardous alternative
Provide personal protective equipment*
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The control measures identified must be specified on the risk assessment and all persons involved in the project should be given enough information, instruction and training to ensure they are working in a safe manner, and are fully aware of the nature of the hazards they are working with and how to correctly use the control measures identified.
Assessment forms are available to download from the Departmental Health and Safety web pages. Each research group is responsible for the holding of its research risk assessment records in such a manner that any required record can be produced on request by an Inspector.
All persons working with hazardous substances must make full and proper use of any control measures provided and must report any defects discovered in any control measure
device or facility to their supervisor and/or the DSO or maintenance where appropriate
As a minimum for work involving hazardous substances follow the precautions as described in the SDS for safe handling
12.1.3 Workplace and Exposure Limits (WELs) Workplace Exposure Limits are Occupational Exposure Limits set under the COSHH Regulations, in order to help protect the health of workers. Substances which have been assigned a WEL include those that are carcinogenic or mutagenic, could cause asthma and other substances that are of significant risk through high levels of inhalation. Exposure limits are in place to control the effects of substances, depending on the nature of the substance and the effects of exposure. Some effects require prolonged exposure, while others may be seen after brief exposures.
WELs are concentrations of hazardous substances in the air, averaged over a specified period of time referred to as a time-weighted average (TWA). Two time periods are used: long-term exposure limit (LTEL) or 8 hour reference period and the short-term exposure limit (STEL) or 15 minute reference period. Exposure limits are quoted both in parts per million (ppm) and in milligrams per cubic metre (mg.m-3).
The 8 hour LTEL is the maximum exposure allowed over an 8 hour period. When calculating the exposure level, if the exposure period is less than 8 hours then the exposure limit can be increased providing that exposure above the LTEL value continues for no longer than an hour. However, the STEL will always take priority over the LTEL.
As WELs are limits it is technically an offence to exceed them. However, there is also an over-riding duty to reduce exposure to the lowest reasonably practicable level below the WEL i.e. they are not just target standards.
The latest list of WELs can be found in the updated HSE publication EH40/2005 (Third edition, published 2018) ‘Workplace Exposure Limits’ which can be downloaded from the HSE website.
12.1.4 Chemical Inventory For a number of safety and security reasons, the University formally adopted a standardised commercial chemical inventory system known as ‘ChemInventory’ to supersede other inventory systems. ChemInventory is free to use and can be used by any group within the department to track the chemicals stored and used in their labs, workshops or plant rooms. All chemicals with the exception of simple easily available commercial cleaning products also known as “householder cleaners” should be entered on to the inventory system. Auditing of the inventory is done whenever questions arise to what chemicals are held and annually to ensure compliance.
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12.2 Labelling All containers of chemicals must be clearly labelled with accurate information as to the contents and where possible, with the appropriate hazard warning symbol (a black pictogram inside a red diamond) e.g.:
Flammable Harmful Corrosive Toxic
Where possible, protect labels with transparent tape and replace immediately any that are damaged. All chemicals should be dated upon receipt and upon opening. They should also be labelled to indicate which storage group they belong to in terms of their hazard class and compatibility.
Synthesised compound samples must also be labelled. The label must contain the molecular structure or IUPAC name, date prepared and the name of the person responsible.
In December 2010, the Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulations were introduced as part of the United Nations Globally Harmonised System (GHS). These Regulations replaced the Chemicals (Hazard Information and Packaging for Supply) Regulations (CHIP) with respect to chemical hazard communication with suppliers having to be fully compliant by 2015. GHS replaced the old square orange pictograms with red edged diamonds and introduced two new pictograms (see below). GHS requires suppliers to use all relevant pictograms up to a maximum of five
Comparison of ‘old’ CHIP and ‘new’ CLP/GHS Hazard Pictograms
Old
New
Old
New
Harmful or Irritant
Explosive
Flammable
Harmful to the Environment
Corrosive
New GHS Symbols
Toxic
Severe Health Hazard: Respiratory Sensitizer
or Carcinogen
Oxidiser
Compressed gas cylinder
Note: There is no legal requirement to re-label existing containers held in laboratories, so both the CHIP and GHS systems of classification are currently in use in practice. It should be noted that GHS changed some of the criteria for hazard classification and labelling.
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12.3 Safe Storage of Chemicals The safe storage of chemicals is essential in order to provide for the effective management of chemicals, lessen the risk of fire, prevent accidental mixing in emergencies, and to minimise exposure to corrosive and toxic chemicals. Safe storage begins with identification of the chemicals to be stored and their intrinsic hazardous properties. Since many chemicals have several hazards, which may vary in degree of severity, depending on quantity and concentration, it is often difficult to determine what protection is needed for safe storage and where best to store a particular chemical.
Separation, segregation or isolation is recommended depending upon the severity of hazard, total quantities stored, and the size and break resistance of individual containers. It is important to note that chemical compatibility must take preference when storing chemicals. Material and size of storage containers will also affect the need for special storage practices and safety procedures.
Ventilation is needed for chemicals and containers that may release dangerous or damaging quantities of vapours or gases that are flammable, corrosive, irritating or toxic. Ventilation may also be needed for containers and chemicals that may produce annoying odours.
Chemicals stored at the bench or other work areas should be those that are used frequently. Quantities should be limited to only the minimum amount that is required for the day’s work.
12.3.1 Chemical Compatibility Many organic and inorganic materials are combustible. Some have such a high degree of combustibility that they are designated flammable.
Organic acids are combustible materials and many of them are combustible liquids. Organic acids can be safely stored with flammable and combustible liquids, but they should generally not be stored with oxidising mineral acids, which could react more or less violently with organic acids.
Oxidisers must be stored separately to avoid contact with incompatible materials such as flammable and combustible liquids, greases, ordinary combustibles and other materials that could react with the oxidiser or catalyse its decomposition, including other oxidisers.
Mineral acids, including those recognised as strong oxidisers, such as nitric acid, perchloric acid and sulfuric acid should be separated from flammable and combustible materials, including acetic acid.
Alkalis/bases are corrosive or irritating. Those that are liquid in large glass containers, such as ammonium hydroxide, they should be stored in a separate cabinet or area.
Toxic chemicals that are acid-sensitive, such as sulfides, should be stored in a separate location from acids or protected from contact with acids.
Dry chemicals can be stored together but organic and inorganic chemicals should be kept separately.
For further information see “Safe Storage of Hazardous Chemicals In Stockrooms, Workshops and Laboratories” http://www.safety.admin.cam.ac.uk/files/hsd051c.pdf
12.4 Handling Chemicals – Reducing the Risks • The minimum quantity of chemical necessary should only be used and hazardous materials
should be safely disposed of as soon as possible after use.
• All chemicals should be regarded as toxic by ingestion. Hence, pipetting liquids or solutions by mouth is strictly prohibited; use a pipette pump/bulb, syringe or a mechanical dispenser. Never deliberately taste, swallow or inhale any chemical.
• Chemicals can also enter the body through the skin or through the accidental inhalation of vapours or dusts. Suitable protective equipment must be worn when handling chemicals. Cuts and wounds are particularly vulnerable and may allow direct entry of chemical substances into the bloodstream. Broken skin should be covered with a suitable dressing, but
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if the wound is on the hand then the dressing should be waterproof and gloves must be worn at all times while handling chemicals.
• It must be assumed that all chemicals will cause damage if allowed to contact the sensitive surface of the eye. Some chemicals have a severe damaging effect, especially acids, alkalis and those chemicals which are classified as corrosive or as irritants. Many solvents fall into this category. Hence, the wearing of safety glasses or other appropriate and approved eye protection in laboratories is mandatory when handling chemical compounds.
• Acids, alkalis and other corrosive materials can cause burns on the skin. Some chemicals have an irritating action and may cause sensitisation or dermatitis, while some others pass freely through the skin barrier and thereby directly into the blood stream. Toxic effects can be almost immediate, but frequently effects are delayed or may result from long-term exposure. Some chemicals are carcinogenic. It is prudent therefore to keep all chemicals off the skin.
• You should be aware of the best method for dealing with accidental skin contact before using a chemical. In many cases the remedial action involves immediate and thorough washing and prolonged rinsing with water and, if in doubt, then this procedure should be used. However, many chemicals are not particularly soluble in water and alternative methods for removal are often necessary (e.g. soap and water may suffice). Do not use organic solvents for the washing process since some of them have the ability to carry contaminants through the skin.
• Always wash your hands after handling chemicals and before touching other parts of your body (especially the area around the eyes) or before consuming food.
• Always wear the approved personal protection (i.e. safety glasses, laboratory coat and sensible stout shoes) and keep bare legs covered. Gloves should be worn when handling chemicals.
• Never carry bottles by the neck or in the pocket. Winchesters must always be carried in a Winchester carrier, that is either inherently leak proof or lined with a leak proof insert.
• Do not overfill bottles or flasks. An air space, equivalent to at least 10% of the total volume (known as ullage), should be left above the liquid to allow for expansion and for safe pouring.
• Chemicals which give off harmful vapours or dust, or which are toxic, odoriferous, volatile or harmful should only be used in a fume cupboard.
• New compounds should be handled with particular care since risks and hazards are unknown. You should assume that they are toxic and take the appropriate precautions.
• Never leave an open container of either a solid or liquid chemical on the open bench top. Tops should be secured after use.
• Acid chlorides, halogenated ethers and the halides and oxyhalides of aluminium, phosphorus, sulfur and tin, often evolve hydrogen chloride or hydrogen bromide when stored, with development of pressure. When opening a bottle of these materials, or of bromine, nitric acid or concentrated ammonia, protect hands and wear a face shield.
• Do not eat or drink in the presence of chemicals. Eating and drinking is not permitted in laboratories, workshops or other areas (including offices) where chemicals and other potential contaminants such as lab coats are present.
For further information on handling chemicals please refer to the code of practice entitled ‘Safe Chemical Practice (SCP) – for the prevention and control of exposure to laboratory chemicals’. That can be downloaded from
12.5 Toxic Materials Toxic materials are classified according to their Lethal Dose 50 (LD50). Currently the EU classify a chemical as very toxic, toxic or harmful according to the LD50 values shown in the table below:
Oral Toxicity Classes as mg/kg
The United Nations Globally Harmonised System (GHS) changed the toxicity classes in a way that resulted in a number of chemicals that were previously classified in the upper end of ‘hazardous’ being reclassified as toxic. In addition, under GHS, nomenclature on containers includes the signal words “Danger” and “Warning”.
12.6 Flammable Materials The majority of organic materials are flammable, and many organic solvents are highly flammable (e.g. ethanol, acetone, diethyl ether, petroleum products, and toluene to name just a few). The degree of flammability is defined by their ‘flash point’. The flash point of a flammable liquid is the minimum temperature at which it forms a vapour above its surface in sufficient concentration to be ignited. The temperature at which burning is sustained will usually be higher and is sometimes called the burning point. The auto-ignition temperature is the minimum temperature at which vapours of the liquid will ignite spontaneously without a source of ignition.
A flammable liquid is defined as a liquid which has a flash-point at or below 60 °C, see below:
Extremely Flammable – Flash point < 0°C and a boiling point ≤ to 35°C
Highly Flammable – Flash point ≤ 23°C
Flammable – Flash point ≥ 23°C and ≤ 60°C
GHS changed the threshold values of the flash points of flammable materials which determine whether a substance is categorised as Flammable, Highly Flammable or Extremely Flammable, and changed the emphasis from flash points to boiling points to distinguish extremely from highly flammable, see below. Some flammable liquids changed their category under GHS and some liquids previously classified as Not Flammable (Flashpoint > 55°C and ≤ 60°C) were reclassified as Flammable under GHS.
Category 5 has not been adopted by
the EU
‘Warning’
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GHS Category Criteria
1 Flash point < 23°C and initial boiling point ≤ 35°C
2 Flash point < 23°C and initial boiling point > 35°C
3 Flash point ≥ 23°C and ≤ 60°C
These categories are then defined as below:
Classification Category 1 Category 2 Category 3
GHS Pictograms
Signal Word Danger Danger Warning
Hazard Statement H224: Extremely
flammable liquid and vapour
H225: Highly flammable liquid and
vapour
H226: Flammable liquid and vapour
Examples of typical flammable liquids are given below:
Flash Point Diethyl Ether -45 °C Extremely Flammable
Acetone -18 °C
Highly Flammable Toluene +4 °C
Ethanol + 16 °C
Petrol < +21 °C
White Spirit +39 °C Flammable
Diesel Fuel ~ +50°C
The quantity of any highly flammable liquid present in a work area must be as small as is reasonably practicable having regard to the processes or operations being carried out. The Dangerous Substances and Explosive Atmospheres Regulations 2002 (DSEAR) place a maximum combined limit of 50 litres of extremely and highly flammable liquid per room i.e. per lab! To comply with this, volumes in excess of 50L per room require storage in Type 90 fire-resisting cabinets to BS EN 14470-1 in-line with HSE guidance, University and Departmental Policy.
In addition, no more than 500 ml nominal capacity of highly and extremely flammable liquids should be kept on the open bench at any one time.
It should be noted that organic solvents and solids often develop quite large electrical charges when being poured out of containers, particularly when polythene funnels are utilised. Whenever possible, metal drums should be earthed to prevent sparks causing an explosion during the removal of the contents. The receiver should also be earthed.
Do not leave Winchesters of flammable solvents on floors, bench tops, open shelves, or fume cupboards. All Winchesters must be closed and returned to the solvent cabinets after use.
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It is important to prevent flammable substances from coming into contact with ignition sources, i.e., gas burners or hot surfaces, or electrical equipment which can arc (e.g. electric motors, light switches, bimetallic strip on/off devices). Minor spillages must be cleaned up quickly. In the event of major spillages, the laboratory should be ventilated by opening the windows, evacuated and the door closed. Do not switch any electrical equipment on or off since this could cause a flashback to the spillage.
Solvents which need to be stored at low temperatures must be kept in spark-free refrigerators/freezers.
In the event of a solvent fire, water should not be used to fight it. Burning solvent usually floats on water and dousing with water can rapidly increase the spread of the fire!
12.7 Highly Reactive Substances and Spontaneously Flammable Solids This class of compound includes alkali metals, alkali metal hydrides, organoalkali metal reagents, lithium aluminium hydride, zinc organometallics and aluminium organometallics. They are all air- and moisture-sensitive and contact with water should be avoided at all times.
TRAINING FROM AN EXPERIENCED GROUP MEMBER MUST BE OBTAINED BEFORE HANDLING ANY OF THIS CLASS OF MATERIAL
WHEN HANDLING SPONTANEOUSLY COMBUSTIBLE SUBSTANCES, FULLY FASTENED COTTON LAB COATS MUST BE WORN AND CONSIDERATION GIVEN TO THE POTENTIAL
FLAMMABILITY OF GLOVES AND PERSONAL CLOTHING (MAN-MADE / SYNTHETIC FABRICS CAN READILY BURN IF IGNITED BY A PYROPHORIC SUBSTANCE)
12.7.1 Organometallic Reagents
It is safest to use organometallics as standardised solutions in an appropriate solvent. Organoalkali metal reagents, zinc organometallics and aluminium organometallics supplied commercially with protective seals (e.g. Sure/Seal and AcroSeal) should be handled in the following way:
• A positive gas flow or over-pressure in the bottle should be produced by attaching a needle to a vacuum line gas outlet that is then thoroughly purged with a flow of nitrogen or argon. The needle is then fed through the septum while the gas flow is continued. A syringe which has been purged with nitrogen or argon can then be used to remove the required quantity of standard solution.
• Alternatively, a balloon filled with nitrogen or argon can be used to produce the over pressure, a needle being attached to the balloon.
• Syringes that lock the needle to the syringe (i.e. Luer-Lock syringes and needles) should be used for transferring reagents.
Certain reagents (e.g. n-butyllithium) may be supplied in bottles without a septum. In such circumstances, the solutions can be removed using an argon- or nitrogen-purged syringe.
Regardless of the circumstances, reagent bottles should be securely clamped while performing any of the manipulations described above.
Never use paper towels to clean syringes or needles contaminated with organometallics as this will result in combustion after a short period of time.
Cylinders containing concentrated or neat organometallics are particularly dangerous and should only be handled with the supervision of an experienced group member. A separate needle valve will be required to dispense material from this type of container, and this should be the correct type recommended by the supplier. The valve should be fitted by an experienced technician. Very rigorous inert-atmosphere techniques must be applied (i.e. use of a vacuum line set-up and Schlenk apparatus). The liquids are fed through a tube into the reaction vessel (under argon or nitrogen).
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Disposal of Residues
Large quantities of organometallics should be diluted with an inert solvent such as toluene (particularly if neat). Isopropanol is added very slowly to the stirred solution under argon or nitrogen, with the reaction vessel being cooled in an ice bath. Water and primary alcohols should never be used for this purpose. Ensure that the reaction is complete before disposing of the solution as chemical waste. Small quantities (such as residues from a syringe) can be rinsed into a beaker and isopropanol added slowly.
12.7.2 Lithium Aluminium Hydride and Alkali Metal Hydrides These are most often used as dispersions in mineral oil. The dispersions can be transferred to reaction vessels (previously purged with nitrogen or argon) using a spatula or large syringe fitted with a large gauge needle. An inert (aprotic) solvent such as dry toluene is added and the oil is washed from the hydride by allowing the solid to settle, then using a syringe to remove the solvent. It is important to have a dry beaker or round bottomed flask available to dispose of the solvent waste, which will contain small amounts of the hydrides.
Hydrides supplied commercially as pure solids should never be handled in the open atmosphere. A glove box should be used for this purpose. They should also be stored in closed containers. Dry lithium aluminium hydride (LiAlH4) often contains finely-divided lithium metal which can result in spontaneous ignition. Dry sodium hydride will often ignite immediately in contact with air.
When weighing out LiAlH4 and lithium borohydride (LiBH4) always use a non-combustible receiver or container to dispense into.
When using LiAlH4:
• Do not assume that different batches of LiAlH4 will react or behave in the same manner.
• Before starting work, make sure that the fume cupboard is clear of all other equipment and flammable material.
• For large scale reactions i.e. > 5g LiAlH4, particularly where using a volatile solvent such as diethyl ether, always assume that thermal runaway is highly likely and ensure that these effects can be mitigated i.e. always have a dry ice/acetone or liquid nitrogen bath at hand to rapidly cool the reaction.
• For particularly large scale reactions it is always good practice to have an experienced member of staff available particularly at the initial stages.
• Constant monitoring is vital – only leave the reaction once it has settled down.
Disposal of Residues Residues can be destroyed by slowly adding isopropanol. Large quantities of metal hydrides should be destroyed under an argon or nitrogen atmosphere, with the hydrides being suspended in an inert solvent and the reaction vessel being cooled in an ice bath. Isopropanol can be used for alkali metal hydrides or lithium aluminium hydride. However, a safer method for lithium aluminium hydride destruction is by the slow and careful addition of ethyl acetate, with cooling and under an inert atmosphere.
12.7.3 Alkali Metals Lithium, sodium and potassium can be handled in air but should never be air-exposed for a prolonged period. They are supplied in mineral oil that can be cleaned off with tissue paper or washed off with an inert solvent (such as toluene or hexane). Residues (including tissue paper) should be washed with iso-propanol before disposal. Rubidium and caesium should only ever be used in a glove box.
12.8 Unstable and Explosive Materials Certain classes of material should always be suspected of being potentially unstable. These include substances with a high degree of unsaturation, or with a significant content of oxygen or nitrogen or both. Halogen atoms in combination with oxygen or nitrogen atoms should also be given careful
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consideration. Examples of unstable substances include acetylenes, perchloric acid, perchlorates, peroxides (including peroxide forming compounds), isopropyl ether, decalin, ethyl nitrate and picric acid.
NEVER USE ANY UNSTABLE SUBSTANCE WITHOUT A SAFE SYSTEM OF WORK
12.9 Carcinogens, Mutagens and Substances Toxic to Reproduction
12.9.1 Prevention of Exposure In the first instance, as with all hazardous substances, exposure to a carcinogen, mutagen and substance toxic to reproduction should be prevented by using a safer alternative where one is available, and its use is reasonably practicable. When considering alternatives, carcinogenic, toxic and other properties of chemical substitutes should be established and taken into account.
When undertaking any synthetic research, synthetic routes should be chosen to avoid the use of carcinogenic, etc. starting materials and to avoid, as far as possible, the formation of by-products, intermediates, wastes or residual contaminants consisting of or containing carcinogenic, etc. substances.
For work involving novel substances derived from a known carcinogenic, etc. substance the novel substance should be assumed to be carcinogenic and thus treated accordingly. Where the toxicological effects are unknown it is always prudent to assume that the substance is highly toxic.
12.9.2 Control of Exposure Prior to commencing work with a carcinogenic material, as with any hazardous material, a thorough risk assessment must be undertaken. Consideration must be given to:
• Whether the substance can be eliminated i.e., whether the work can be done in some other way.
• Whether the substance can be substituted by a non- or less hazardous substance.
• The type of hazard (gas, fume, dust, etc.).
• The route by which the particular substance(s) can enter the body, be it by inhalation, ingestion or penetration of the skin, mucosal surfaces or eyes.
• Level of exposure.
• Operating and maintenance instructions and procedures (where applicable).
• Maintenance and emergency procedures.
Exposure to a carcinogenic substance should be controlled by total containment of the substance or process. Whilst this is unlikely to be possible, the use of glove boxes, etc. must be employed if reasonably practicable, particularly where a carcinogenic substance presents a dust or vapour inhalation hazard. Where total containment of a carcinogenic substance or process is not possible, carcinogenic substances should be used within a fume cupboard.
Where it is not possible to totally or partially enclose a process, which presents a carcinogenic dust or vapour inhalation hazard (e.g. wood dust in a work shop), then local exhaust ventilation (LEV) must be used as a minimum and respiratory protective equipment (RPE) worn.
Glove boxes and fume cupboards where work involving carcinogenic substances is undertaken must be clearly designated with a ‘Carcinogenic Hazard’ warning sign. Walls, floors and other surfaces in areas where carcinogenic substances are used must be cleaned i.e. washed down at regular intervals and whenever necessary.
Only the minimum amount of carcinogenic substance necessary may be used, and the number of people likely to be exposed and the duration of their exposure must be kept to a minimum. It is essential that all work involving carcinogenic substances be thoroughly planned in advance.
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The appropriate protective clothing must be worn when manipulating/working with carcinogenic substances. This includes the wearing of gloves made of a suitable material to provide protection against accidental skin contact; wearing clean, if necessary, disposable, protective clothing in addition to a laboratory coat and eye protection. It should be noted that laboratory gloves provide only very limited protection and should be discarded appropriately and immediately following contamination.
In order to avoid spreading contamination from the site of use of a carcinogenic substance, the following precautions must be taken:
• Weighing of materials and preparation of solutions must only take place within an adequate fume cupboard or other well-ventilated enclosure.
• Care must be taken to avoid contaminating the exterior of containers. Any such contamination must be cleaned off in the fume cupboard or ventilated enclosure prior to returning to store.
• Care must be taken to avoid the formation of airborne dust or processes that may give rise to aerosols.
• Apparatus and glassware contaminated with carcinogens are the responsibility of the person who used it. The contaminated apparatus and glassware must not be placed in communal washing-up containers nor washed up by non-technical staff but must be cleaned within a fume cupboard and any washings, including solvent, carefully stored as waste.
• Spills within the fume cupboard must be cleared up carefully and any materials used disposed of as carcinogenic waste.
• Users must never touch door handles, light switches or telephones with gloves (assumed contaminated) or wear gloves outside the laboratory. Gloves should be removed using the proper ‘surgical’ procedure to avoid skin contamination.
• Contaminated tissues, filter-papers, absorbent tray liners, disposable laboratory wear including laboratory gloves, ion-exchange materials and other solid waste must be sealed in clearly labelled plastic bags for disposal as carcinogenic chemical waste. Contaminated material must not be allowed to accumulate in the laboratory.
• Practice careful hygiene and wash and dry hands thoroughly before leaving the laboratory.
The use of sharps in procedures involving carcinogenic substances should be avoided. Disposable sharps including broken glass must be decontaminated before disposal and the washings treated as carcinogenic chemical waste.
12.9.3 Health Surveillance & Health Records Health surveillance is a system of ongoing health checks. These health checks may be required by law for employees who are exposed to noise or vibration, ionising radiation, work in compressed air and are required by COSHH 2002 Regulations for individuals working with substances such as solvents, fumes, dusts, biological agents and other substances hazardous to health that can cause certain identifiable diseases or adverse health effects. Health surveillance is requisite in the case of substances known to, or suspected of causing cancer of the skin, e.g. arsenic, used mineral oils and chromic acid. Individuals who work with respiratory sensitizers, skin sensitizers, mercury, latex, and arsenic will have additional health surveillance arranged by the Occupational Health Service. Health surveillance is appropriate in the case of work with all category 1 and 2 carcinogens, mutagens and substances toxic to reproduction, respiratory sensitizers and skin sensitizers (i.e. substances having the following Risk Phrases or Hazard Statements: R42 / H334, R43 / H317, R45 / H350, R46 / H340, R49 / H350i, R60 / H360f, R61 / H360d, R64 / H362), organophosphorus compounds, mercury or mercury compounds (where exposure to vapour or dust is possible), cadmium, or cadmium compounds (where exposure to vapour or dust is possible), and burning lead (i.e. welding processes using lead). Health surveillance would also be required if failure of any control measure identified in the risk assessment could lead to a significant exposure.
Based on a risk assessment, exposure can be deemed to be insignificant if, under normal operating conditions, exposure is unlikely to result in any disease or adverse health effect.
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For most workers, a person’s involvement in such work is confined to recording and maintaining all health surveillance results on the Health Record Form.
As a pre-cautionary measure, the University also requires health surveillance for all individuals working with Nanoparticles.
Substances found in this Department, where health surveillance is likely to be necessary include (to name but a few):
Arsenic and its compounds Ethylene dichloride
Benzene Lead compounds
Carbon tetrachloride Man-made mineral fibers
Carbon monoxide Nickel compounds
Chromium compounds, including chromic acid Trichloroethylene
The names of all persons using any of the substances detailed above should be notified to the DSO annually (1 October) and individual Health Record Forms completed. Health Record Forms are available from the Department’s Health & Safety website going to https://www.safety.admin.cam.ac.uk/policy-guidance/chemical/hsd033c-coshh-health-record-form
12.10 Controlled Chemicals
12.10.1 Controlled Drugs, Drug Precursors and Scheduled Poisons Controlled drugs can only be purchased having first obtained a licence from the Home Office. For further information, see the DSO.
It must be borne in mind that if your synthetic strategy includes the synthesis of drugs in Schedule 1 of the Misuse of Drugs Regulations 2001 and you intend to retain the intermediates, a licence will be required. However, if the intermediate is immediately consumed in a reaction, Home Office advice is that a licence would not ordinarily be required (see the Departmental Health and Safety website for a list of the most commonly encountered drugs currently controlled under the Misuse of Drugs legislation).
All orders for Category 1 drug precursors (see list below) must be discussed with the DSO in advance in order that the necessary licences are in place before you can proceed with your order.
When applying for the relevant licences the DSO will require a description of the envisaged type of operations (i.e. a description of the synthetic strategy). Any mixture or natural product containing any of the above chemicals will also require a licence. For further information, see the DSO.
Scheduled poisons and drugs are kept in a locked safe/fridge within Stores. Access to the safe is via the DSO only.
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You can only draw out that required for your individual experiment. Bottles must be returned to Stores by no later than 4:00 pm the same day.
It is also recommended that certain alkaloids and their derivatives, e.g. aconitine, brucine, ecgonine and atropine which do not appear on the Poisons List and digitoxin and digitonin, valinomycin and actinomycin D, are also kept locked away. Very toxic chemicals, i.e. those which have Lethal Dose Values LD50 (30 days) of less than 10mg/kg, should also be locked away at the end of each working day and tightly managed/controlled within the research laboratory.
12.10.2 Desensitised Explosives
Picric Acid and other desensitised explosives (see table below) are controlled and require the Department to have a licence to store explosives under The Explosives Regulations 2014. The licence enables the Department to acquire and keep certain chemicals as listed on the Explosives Certificate. 1-Hydroxybenzotriazole, anhydrous (UN0508) and 1-Hydroxybenzotriazole, monohydrate (UN3474) (HOBt) currently has a HSE research exemption from the above requirements so that it may be ordered and held in the same way as any other unregulated compound.
Examples of Desensitised Explosives (Class 3 and Division 4.1)
n.o.s.* = ‘Not Otherwise Specified’
Note:
• Picric acid (2,4,6 trinitrophenol) – is classified under UN regulations for transport by its water content. There are two relevant UN numbers for picric acid, UN3364 (≥ 10% water by mass), and UN 1344 (≥30% water by mass). Picric acid products marketed and transported in formulations that trigger these classifications for transport also trigger the requirements for registration and certification. However, in some cases it may be possible to purchase pre-made products with much lower concentrations of picric acid (< 2% picric acid) that both avoid the need for documentation and the risks of handling and storage (i.e. Bouin’s fixative with 0.9% picric acid).
All orders for desensitised explosives must be discussed with the DSO in advance in order that the necessary licences are in place before you can proceed with your order.
Proper Name UN Number Class
Picric acid (2,4,6 trinitrophenol) with ≥ 10% water, by mass 3364 4.1D Nitroglycerin mixture desensitized, solid, n.o.s.* with more than 2% but not more than 10% nitroglycerin 3319 4.1 D
Nitroglycerin mixture desensitized, liquid, flammable, n.o.s.* with not more than 30% nitroglycerin by mass 3343 3 D
Penta erythrite tetranitrate mixture, desensitized, solid, n.o.s.* with more than 10% but not more than 20% PETN by mass 3344 4.1 D
Nitroglycerin mixture desensitized, liquid, n.o.s.* with not more than 30% nitroglycerin by mass 3357 3 D
Trinitro chlorobenzene (Picryl chloride), wetted with ≥ 10% water by mass 3365 4.1 D
Trinitrotoluene, wetted with ≥ 10% water by mass 3366 4.1 D
Trinitrobenzene, wetted with ≥ 10% water by mass 3367 4.1D
Trinitrobenzoic acid, wetted with ≥ 10% water by mass 3368 4.1 D
Urea nitrate, wetted with ≥ 10% water by mass 3370 4.1 D
Desensitized explosive, Liquid n.o.s.* 3379 3 D
Desensitized explosive, Solid n.o.s.* 3380 4.1 D
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Upon receipt, all desensitised explosives must be retained in a locked safe/fridge within Stores. Access to the safe is via the DSO or named individuals as detailed on the licence only. You can only draw out that required for your individual experiment. Bottles must be returned to Stores by no later than 4:00 pm the same day.
12.10.3 Inorganic Cyanides All inorganic cyanides are held in locked cabinets within Stores. Inorganic cyanide compounds will not be issued from the Stores until:
• A briefing and relevant form has been obtained from a Floor Technician on the protocol for working with these compounds.
• A written authorisation is obtained from the Principal Investigator/Supervisor, which is also signed by the Floor Technician and Cyanide Trained First Aider on call.
YOU MUST WARN OTHER OCCUPANTS OF YOUR LABORATORY THAT YOU ARE USING CYANIDE AND PUT UP THE RED HAZARD NOTICE
12.10.4 Hydrofluoric Acid (HF), including HF-Pyridine Mixtures
12.10.4.1 Small Scale Use of Hydrofluoric Acid (HF) Small scale use of HF within the Department is defined as working with the equivalent of less than 1ml of HF at a concentration at or below 10% used at or below room temperature i.e., 1 ml of 10%, 10 ml of 1% or 100 ml of 0.1% etc. at or below 25 °C. However, the handling of concentrated stock solutions (40% / 70%) will require additional precautions. Work at elevated temperatures (> 25°C) should be assessed by a competent person to determine appropriate control measures.
Small scale work with HF may be undertaken by Researchers who have been trained and are judged to be competent to do so by their Supervisor or by an experienced Technician familiar with using HF.
Those carrying out small scale procedures must use appropriate personal protective equipment (PPE) and be aware of the unique hazards presented by HF and in particular its potential acute toxicity by skin absorption of the fluoride ion.
Small scale work should only be carried out when a ‘Small Scale HF Emergency Kit’ (orange box) containing in-date calcium gluconate gel is immediately available in the laboratory close to the work area.
The ‘Small Scale HF Emergency Kits’ are available from the DSO / DST and should be kept in a known, clearly visible, clean location in the laboratory where the HF is being used.
Each kit should be the responsibility of a named individual, maintained in a good condition and the gel replaced at or before its expiry date or if the tube is opened / used.
UNDER NO CIRCUMSTANCES MUST THE PRESENCE OF AN ORANGE ‘SMALL SCALE HF EMERGENCY RESPONSE KIT’ BE TAKEN TO PERMIT THE USE OF LARGER QUANTITIES
OF HF IN EXCESS OF THE ABOVE THRESHOLD
12.10.4.2 Larger Scale Use of Hydrofluoric Acid (HF) The use of significant quantities of hydrofluoric acid (HF) in excess of the small scale quantities threshold above, is restricted to between 9:00 am and 5:00 pm, Monday to Friday. In preparation for using HF, the researcher must complete a “Hazardous Chemical Requisition” form (available from the Departmental Safety “form” web page) and get the required three signatures. The First Aider must be notified of how much HF is to be used and location of use, and they must be shown a full written protocol and risk assessment. The completed form is not used to obtain HF, as it is stored in laboratories, but to obtain a HF/CN kit from reception which is taken to the lab where the work is to be done.
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HF should only be handled by trained users and should only be used in a fume cupboard. All work must be performed in a plastic containment tray within the fume cupboard. No other work should be undertaken within the fume cupboard whilst HF is being handled.
Face protection (safety glasses and face shield) and gloves (PVC or neoprene rubber) must be worn at all times when handling HF. If decanting significant quantities of acid into containers, a rubber apron and rubber boots should be worn. Gloves and other impervious clothing must be washed prior to removing them. Test reusable gloves for pinholes before putting them away.
Spillages including drips that run down the side of the HF bottle should be neutralised with saturated sodium carbonate solution and washed to drains with copious amounts of water.
ALL burns should be treated at the Emergency Department at Addenbrooke’s Hospital.
• In case of HF contact with the skin, do not wait for pain or symptoms (which can be delayed by 24 hrs), treat immediately. Flush the affected area with water for at least 10 minutes. Then apply calcium gluconate gel, gently massaging it into the burn. Continue for at least 15 minutes or until the pain has subsided (whichever is the longer). The treatment can be continued during transit to hospital.
• In case of contact with the eyes, immediately flush the eye with Hexafluorine eyewash and continue for at least 20 minutes. This can be done during transit to hospital.
Contaminated clothing must be removed immediately and disposed of.
Caution: It is generally believed that Ammonium bifluoride (NH4HF2) based products are harmless or inherently safer than HF. This is a potentially dangerous misconception. Ammonium bifluoride presents virtually the same risks as HF and in fact forms varying concentrations of HF when dissolved. Always treat either one with the same precautions.
12.10.5 Malodorous Materials The use of malodorous thiols and mercaptans (particularly those that smell of gas) MUST be notified to the Department prior to work commencing. All use of thiols, workups of thiol reactions and disposal of solutions (i.e. reaction mixtures that have been destroyed by oxidation with bleach and disposed of via the drain) must be reported.
To notify your intended use of malodorous chemicals, please complete the online form on the Departmental Health and Safety website which will automatically email the [email protected] email list with all the required information.
When working with thiols and mercaptans, ensure that your reaction is aspirated through an in-line bleach bath (Dreschel bottle).
If you are reporting a strange smell in the building, please telephone Reception (Extn. 36300).
12.10.6 Mercury Mercury is a highly toxic, fairly unreactive metal that is resistant to corrosion. Repeated or prolonged exposure to mercury vapour can result in damage to the central nervous system, however the acute toxicity of mercury varies significantly with the route of exposure. Mercury is a bio-accumulator and poses an environmental hazard.
Due to the conditions of the Trade Effluent Consent agreement with the Environment Agency, the use of elemental mercury, mercuric compounds and equipment containing mercury (e.g. thermometers, and manometers) is being phased out within the Department. The use of alternatives must be explored at all times.
Elemental mercury may only be kept for designated uses and authorisation is required from the DSO. Holdings of mercury and mercuric compounds and mercury containing equipment must be logged on the mercury database which is managed by the DSO.
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Containers of elemental mercury (where storage has been authorised) should be kept tightly sealed and stored in secondary containers (such as a plastic tray, bottle or pan) in a well-ventilated area.
Where breakage of instruments or apparatus containing mercury is possible, the equipment must be placed in a plastic tray or pan that is large enough to contain the mercury in the event of an accident.
Transfers of mercury between containers must be carried out in a fume cupboard over a tray or pan to confine any spills.
Metallic Mercury Spillages Spilled elemental mercury can give rise to a dangerous concentration of vapour in an enclosed room. In the event of a spillage, the following procedures must be followed:
• Isolate the area and open all windows. Good ventilation is paramount.
• Notify the Floor Technician immediately.
• Wear suitable protective clothing including gloves and respiratory protective equipment (if appropriate).
• Visible mercury should be removed by either suction into a plastic bottle using an aspirator bulb or a vacuum device or a mercury spill kit. DOMESTIC VACUUM CLEANERS MUST NOT BE USED.
• Liberally treat all affected areas (floor, bench tops) with either:
o a mixture made by adding equal parts of flowers of sulfur and calcium hydroxide to water to form a paste. Allow at least 12 hours to elapse before removing the dried yellow mixture with clean water. Repeat to ensure the surfaces are clean. The area should then be mopped using a dilute suspension of one drop washing up liquid and 2 heaped teaspoons each of sulfur and calcium hydroxide.
o or a 10% copper sulphate solution. Any remaining mercury will appear copper coated thus making it clearly identifiable.
• If the mercury spillage is small and spilt into floor cracks and crevices it should be made non-volatile immediately by flushing with 10% copper sulphate solution or by putting zinc dust into the cracks in order to form an amalgam. Notify the Floor Technician and DSO immediately as mercury vapour monitoring will be required.
• All mercury cleanup material should be placed in a plastic bottle or double bagged and disposed of via the Chemical Waste Store.
• If the spillage is into a sink, isolate the sink and contact Maintenance immediately.
Note: The common practice of covering spilt mercury with flowers of sulfur should be discontinued because the practice is ineffective.
12.11 Disposal of Chemicals The uncontrolled disposal of solid, liquid or gaseous hazardous and toxic waste is strictly forbidden. Never dispose of chemicals by throwing them in the waste bin. Never dispose of hazardous or toxic chemicals down the sink.
Research workers are responsible for disposal of all unwanted chemicals in a safe and proper manner in accordance with Departmental Policy as detailed in the Waste Charts
Any spilt chemicals should be cleaned up immediately
Hazardous chemical waste must be segregated with due regard to chemical compatibility/properties in order to prevent the likelihood of reactions occurring in storage or transit, which could cause danger to persons or property, or environmental pollution.
Containers must be suitable for the type of waste. In general the following guidelines should be followed:
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• Glass bottles can be used for most chemicals except hydrofluoric acid waste.
• Plastic bottles are suitable for acids and alkalis. Do not put aggressive solvents such as diethyl ether or dichloromethane, or mixtures containing aggressive solvents, in plastic containers unless the container is made of HDPE.
• Containers designed for solids must not be used for liquids.
Care must also be taken to ensure that there is no external contamination of the container. Where external contamination is suspected, containers must be sealed inside a clear plastic bag or placed into a secondary container.
Containers must not be overfilled. Winchesters should be filled to the bottom of the neck and no higher. If the Winchester contains a highly flammable liquid then it should not be filled above 3/4 full. In the warmer weather, caps should not be over tightened and Winchesters should not be filled more than 2/3 full. 1% air-space should be left in steel drums to allow for volume expansion in warm weather. Bungs on the steel drums must be correctly tightened.
Containers must be clearly labelled with full details of contents and the name of the person transferring the waste. Major components must be listed and where possible the original container should be used as this gives valuable identification and safety information. Where the original container is used, the label should not be obscured. However, it is important to deface or preferably remove any labels on packaging which are incorrect. Where secondary containment is used, the outer container must be labelled with the contents.
All waste for disposal must be listed on the Departmental Hazardous Waste Disposal Application Form (available to download from the Departmental Safety web pages) and then placed in the grey plastic waste boxes available from the Waste Store. The key to the Chemical Waste Store is available from Reception between 9:00 am and 4:00 pm Monday to Friday.
Forms must be placed inside the box of chemicals to which it relates. For single bottles, the form should be secured to the outside of the container. Boxes of chemicals and bottles should be placed on the shelving.
Do not interfere with any other items or chemicals present in the store
Note: Research workers leaving the Department are responsible for the cleaning of general glassware and for the disposal of unwanted chemicals and products. Unwanted materials left in flasks constitute a future hazard (especially if unlabelled), and they cost the Department a considerable sum of money each year (both for the disposal fee and the loss of glassware).
12.11.1 Storage and Disposal of Acids Concentrated acids must be stored in a separate cabinet, away from organic solvents and bases, in case of leaks leading to an explosion. Acids can be disposed as hazardous waste whether concentrated or dilute. In circumstances where aqueous acid waste is produced regularly, particular care should be taken in storage prior to disposal. Waste bottles should be clearly labelled with a safety warning and a note that organic solvents should not be added to aqueous acid waste under any circumstances, i.e., DANGER - AQUEOUS ACID WASTE. DO NOT ADD ORGANIC SOLIDS OR SOLVENTS. Addition of organic material to concentrated acids can result in highly exothermic, explosive reactions which can also generate large quantities of toxic gases. Waste bottles should be made of plastic (not glass) and fitted with vented or loose-fitting lids, and stored in a fume cupboard.
Only if no toxic material is present, the neutralised waste can be disposed of down a sink. Concentrated acids should always be diluted first before being neutralised and the pH checked before disposal. It is important that the acid is added to water not the other way around, as rapid addition of water to concentrated acids can result in localised boiling and splash back. The situation and state of acid waste containers should be monitored by a responsible group member and waste should not be allowed to build up. If acid waste is generated regularly, for example, as part of a particular research programme, then it is advisable that the disposal protocol forms part of the local induction for new group members.
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Under no circumstances should Aqua Regia or nitrating mixtures be disposed of without dilution and neutralisation
Some research groups use concentrated acid baths (normally HCl) to clean glassware, in conjunction with KOH(aq)/EtOH or KOH(aq)/iPr2OH. These should not be used on the open bench; however it is reasonable to dispose of both baths at the same time, by adding the diluted acid bath to the diluted base bath. The pH should be checked before disposal (according to the protocol set out above).
12.11.2 Malodorous Materials If possible, destroy in the fume cupboard (e.g. thiols may be oxidised with permanganate or bleach). Otherwise these compounds should be listed separately and the form passed to the DSO who will arrange for these compounds to be disposed of directly from your laboratory. Such materials should never be transported in open containers.
12.11.3 Cyanides Warning: the following procedure should only be used with those cyanide residues that are known to be safe as a result of ‘universal usage’.
If a novel procedure is used without a known history of safe neutralisation or if the compounds used, and therefore potentially present in the residue, contain high levels of sulfur and/or nitrogen then the neutralisation must not be used. In this case the residue must be treated as hazardous waste and be disposed of via the Department’s Hazardous Chemical Waste Store.
All aqueous cyanide waste deposited in the Chemical Waste Store must be appropriately packaged and clearly labelled; containers should wherever possible be constructed of robust plastic and should not be entirely airtight but should have a vented cap, to avoid over pressurisation in the event of an adverse reaction.
In conclusion unless the neutralisation is being performed on a straightforward INORGANIC residue the default option should be to treat the residue as hazardous waste for disposal via the Department’s Waste Store as detailed above.
12.11.4 Spent Catalysts Never put a spent hydrogenation catalyst in the waste bin; it may catch fire spontaneously later. Osmium, platinum and palladium residues should be damped down with water, kept separate and prepared to be disposed of as chemical waste where they will be sent for recovery. Other catalysts such as Raney nickel, should be stored under water to exclude air, ready for disposal.
12.11.5 Silica Waste Crystalline silica is a respiratory sensitizer. Possible long term effects of dust inhalation include silicosis and other related pulmonary respiratory diseases. Exposure to silica dust causes the lung to produce fibrotic nodules, which over a period of time will change in size leading to increasing breathlessness and eventual death. Particles of 1-2 µm in diameter appear to be the most fibrogenic. However, there is still much uncertainty as to the effect of amorphous forms of silica and their potential to cause disease. Whatever the mechanism of the disease, it is plain that the more respirable crystalline silica and associated dust that is inhaled, the greater is the chance of illness which may well manifest itself in later years.
Care must be taken to avoid the generation of airborne dust (often invisible to the naked eye) by containment, or whatever preventive measures are applicable (including wearing personal protective equipment e.g. a face mask, which would require a face-fit test). Airborne silica is likely to be generated when filling and emptying columns, and when scraping bands from plates. Spent silica from columns and plates should be placed in the dedicated waste silica bins.
DO NOT dispose of used TLC plates via the mainstream clean broken glass route (i.e. via the white cardboard Fisher glass disposal boxes obtained from Stores). All TLC plates MUST be disposed either with the waste silica, if collected in blue drums, or in the designated blue barrels. Please check with your Floor Technician if you do not have an appropriate container. On no account should glass plates be mixed with waste silica that is contained within plastic bags.
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A disciplined and good housekeeping approach to the handling of silica and prevention of it becoming airborne are of paramount importance. This also means not allowing unsightly piles of used plates to accumulate on benches. Natural convectional air currents are sufficient to disturb silica and for it to become airborne.
12.11.6 Chemically Contaminated Sharps Waste Chemically contaminated sharps must be disposed of via a dedicated sharps bin/container, which are available from Stores. These are normally supplied with a clinical waste/infectious substance label and Biohazard trefoil sign.
Prior to disposing of the bin through the Chemical Waste Store, please ensure that the Biohazard trefoil sign on the bin has been covered by the label issued with the bin or defaced, and any reference to the UN Carriage Number (UN 2814 Infectious substance) has been removed. The bin should be labelled with the Research Group/Technical Section, contact name and telephone number.
Sharps bins must only be used to dispose of the following: knife blades, needles, needles with syringe bodies attached and broken, contaminated glass. They MUST NOT be used for the disposal of paper towels, gloves, pipette tips and other plastic consumables (excluding syringe bodies and scalpel handles).
HPLC and LCMS vials should be disposed of separately. Dedicated sharps bin/containers can be used providing the waste are properly segregated.
12.11.7 Research samples For waste that is in a small vial in the region of < 25 g or < 25 ml, then the waste can be described and labelled as "research sample". If there are many such samples, then they can collectively be disposed of in a plastic container or glass Winchester, in a blue plastic metal latch clip drum or double bagged using robust transparent plastic bags. On the “Application For Disposal of Hazardous Chemicals” Form, provide some indication of hazards, pH, and incompatibilities if known.
12.12 Safety Terminology Safety Data Sheets (SDS) and labels convey pertinent safety information through pictograms and a series of Hazard and Precautionary Statements. Hazard Statements (which replaced the Risk Phrases under CHIP) indicate the hazards inherent in the substance, and include risks to health, the environment and in relation to fire and explosion whereas Precautionary Statements (which replaced the Safety Phrases under CHIP) indicate the precautions to be taken in using and handling the substance or preparation.
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GHS Hazard Statements and comparable Risk Phrases
Code Hazard Statement Comparable R-Phrase
EUH0** Special EU Supplementary General Physical Hazard Statements
EUH001 Explosive when dry R1 EUH006 Explosive with or without contact with air R6 EUH014 Reacts violently with water R14 EUH018 In use, may form flammable/explosive vapour-air mixture R18 EUH019 May for explosive peroxides R19 EUH029 Contact with water liberates toxic gas R29 EUH030 Can become highly flammable in use R30 EUH031 Contact with acids liberates toxic gas R31 EUH032 Contact with acids liberates very toxic gas R32 EUH044 Risk of explosion if heated under confinement R44 EUH059 Hazardous to the ozone layer R59 EUH066 Repeated exposure may cause skin dryness or cracking R66 EUH070 Toxic by eye contact R39-41 EUH071 Corrosive to the respiratory tract
EUH2** Special EU rules for supplemental label elements for certain substances or mixtures
EUH201 Contains lead. Should not be used on surfaces liable to be chewed or sucked by children
EUH202 Cyanoacrylate. Danger. Bonds skin and eyes in seconds. Keep out of the reach of children
EUH203 Contains Chromium (VI). May produce an allergic reaction EUH204 Contains isocyanates. See information supplied by the manufacturer
EUH205 Contains epoxy constituents. See information supplied by the manufacturer
EUH206 Warning! Do not use together with other products. May release dangerous gases (chlorine)
EUH207 Warning! Contains cadmium. Dangerous fumes are formed during use. See information supplied by the manufacturer. Comply with the safety instructions
EUH208 Contains (name of sensitizing substance). May produce an allergic reaction
EUH209 Can become highly flammable in use or Can become flammable in use EUH210 Safety data sheet available on request H2** Physical Hazard Statements H200 Unstable explosives H201 Explosive; mass explosion hazard H202 Explosive, severe projection hazard H203 Explosive; fire, blast or projection hazard H204 Fire or projection hazard H205 May mass explode in fire H220 Extremely flammable gas R12 H221 Flammable gas R10 H222 Extremely flammable aerosol R12 H223 Flammable aerosol R10 H224 Extremely flammable liquid and vapour R12 H225 Highly flammable liquid and vapour R11 H226 Flammable liquid and vapour R10
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Code Hazard Statement Comparable R-Phrase
H228 Flammable solid R10 H240 Heating may cause an explosion R5 H241 Heating may cause fire or explosion R5, R7 H242 Heating may cause a fire R7, R12 H250 Catches fire spontaneously if exposed to air R17 H251 Self-heating: may catch fire H252 Self-heating in large quantities: may catch fire
H260 In contact with water releases flammable gases which may ignite spontaneously
R15-17
H261 In contact with water releases flammable gas R15 H270 May cause or intensify fire; oxidizer R8 H271 May cause fire or explosion; strong oxidizer R9 H272 May intensify fire; oxidizer H280 Contains gas under pressure; may explode if heated H281 Contains refrigerated gas; may cause cryogenic burns or injury H290 May be corrosive to metals H3** Health Hazard Statements H300 Fatal if swallowed R28 H301 Toxic if swallowed R25 H302 Harmful if swallowed R22 H304 May be fatal if swallowed and enters airways R65 H310 Fatal in contact with skin R27 H311 Toxic in contact with skin R24 H312 Harmful in contact with skin R21 H314 Causes severe skin burns and eye damage R34, R35 H315 Causes skin irritation R38 H317 May cause an allergic skin reaction R43 H318 Causes serious eye damage R41 H319 Causes serious eye irritation R36 H330 Fatal if inhaled R26 H331 Toxic if inhaled R23 H332 Harmful if inhaled R20
H334 May cause allergy or asthma symptoms or breathing difficulties if inhaled R42
H335 May cause respiratory irritation R37 H336 May cause drowsiness or dizziness R67
H340 May cause genetic defects (state route of exposure if it is conclusively proven that no other routes of exposure cause the hazard)
R46
H341 Suspected of causing genetic effects (state route of exposure if it is conclusively proven that no other routes of exposure can cause the hazard)
R68
H350 May cause cancer (state route of exposure if it is conclusively proven that no other routes of exposure cause the hazard)
R45
H350i May cause cancer by inhalation R49
H351 Suspected of causing cancer (state route of exposure if it is conclusively proven that no other routes of exposure cause the hazard)
R40
H360 May damage fertility (H360F) or the unborn child (H360D) (state specific effect if known) (state route of exposure if it is conclusively proven that no other routes of exposure cause the hazard)
R60 (H360F), R61 (H360D)
H361 Suspected of damaging fertility (H361f) or the unborn child (361f) (state specific effect if known) ( state route of exposure if it is conclusively proven that no other routes of exposure cause the hazard)
R62 (H361f), R63 (H361d)
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Code Hazard Statement Comparable R-Phrase
H362 May cause harm to breast fed children R64
H370 Causes damage to organs (or state all organs affected, if known) (state route of exposure if it is conclusively proven that no other routes of exposure cause the hazard)
R39/23,R39/24, R39/25,R39/26, R39/27, R39/28
H371 May cause damage to organs (or state all organs affected, if known) (state route of exposure if it is conclusively proven that no other routes of exposure cause the hazard)
R68/20, R68/21, R68/22
H372 Causes damage to organs (or state all organs affected, if known) through prolonged or repeated exposure (state route of exposure if it is conclusively proven that no other routes of exposure cause the hazard)
R48/23, R48/24, R48/25
H373 May cause damage to organs (or state all organs affected, if known) through prolonged or repeated exposure (state route of exposure if it is conclusively proven that no other routes of exposure cause the hazard)
R48/20, R48/21, R48/22
H4** Environmental Hazard Statements H400 Very toxic to aquatic life R50
H401 To avoid risks to human health and the environment, comply with the instructions for use
H410 Very toxic to aquatic life with long lasting effects R53 H411 Toxic to aquatic life with long lasting effects R51-53 H412 Harmful to aquatic life with long lasting effects R52-53 H413 May cause long lasting harmful effects to aquatic life R53
GHS Precautionary Statements and comparable Safety Phrases
Code Precautionary Statement Comparable S-Phrase
P1** General Precautionary Statements P101 If medical advice is needed, have product container or label at hand S45 P102 Keep out of reach of children P103 Read label before use P2** Prevention Precautionary Statements P201 Obtain special instructions before use P202 Do not handle until all safety precautions have been read and understood P210 Keep away from heat / sparks / open flames / hot surfaces - No Smoking P211 Do not spray on an open flame or other ignition source P220 Keep / Store away from clothing/…/combustible materials P221 Take any precaution to avoid mixing with combustibles/.. P222 Do not allow contact with air.
P223 Keep away from possible contact with water, because of violent reaction and possible flash fire
P230 Keep wetted with… S5 P231 Handle under inert gas S6 P232 Protect from moisture S8 P233 Keep container tightly closed S7 P234 Keep only in original container P235 Keep cool S3 P240 Ground / bond container and receiving equipment P241 Use explosion-proof electrical / ventilating / lighting equipment P242 Use only non-sparking tools P243 Take precautionary measures against static discharge S33
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Code Precautionary Statement Comparable S-Phrase
P244 Keep reduction valves free from grease or oil P250 Do not subject to grinding / shock / friction P251 Pressurized container: Do nor pierce or burn, even after use P260 Do not breathe dust / fume / gas / mist / vapour / spray S23 P261 Avoid breathing dust / fume / gas / mist / vapour / spray S24 P262 Do not get in eyes, on skin, or on clothing S25 P263 Avoid contact during pregnancy / while nursing P264 Wash thoroughly after handling S28 P270 Do not eat, drink or smoke when using this product S20-21 P271 Use only outdoors or in a well-ventilated area P272 Contaminated work clothing should not be allowed out of the work-place P273 Avoid release to the environment
P281 Use personal protective equipment as required P282 Wear cold insulating gloves / face shield / eye protection P283 Wear fire / flame resistant / retardant clothing P284 Wear respiratory protection P285 In case of inadequate ventilation wear respiratory protection S38 P3** Response Precautionary Statements P301 If swallowed: P302 If on skin: P303 If on skin (or hair) P304 If inhaled: P305 If in eyes: P306 If on clothing: P307 If exposed: P308 If exposed or concerned: P309 If exposed or if you feel unwell: P310 Immediately call a POISON CENTRE or doctor / physician P311 Call a POISON CENTRE or doctor / physician P312 Call a POISON CENTRE or doctor / physician if you feel unwell P313 Get medical advice / attention P314 Get medical advice / attention if you feel unwell S45 P315 Get immediate medical advice / attention P320 Specific treatment is urgent (see … on this label) P321 Specific treatment (see … on this label) P322 Specific measures (see … on this label) P330 Rinse mouth S64 P331 Do not induce vomiting P332 If skin irritation occurs: P333 If skin irritation or rash occurs: P334 Immerse in cool water / wrap in wet bandages P335 Brush off loose particles from skin P336 Thaw frosted parts with lukewarm water. Do not rub affected area. P337 If eye irritation persists: P338 Remove contact lenses, if present and easy to do so. Continue rinsing
P340 Remove to fresh air and keep at rest in a position comfortable for breathing S63
P341 If breathing is difficult, remove to fresh air and keep at rest in a position comfortable for breathing
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Code Precautionary Statement Comparable S-Phrase
P342 If experiencing respiratory symptoms: P350 Gently wash with plenty of soap and water P351 Rinse cautiously with water for several minutes S28 P352 Wash with plenty of soap and water P353 Rinse skin with water / shower
P360 Rinse immediately contaminated clothing and skin with plenty of water before removing clothes
P361 Remove / take off immediately all contaminated clothing S27 P362 Take off all contaminated clothing and wash before reuse P363 Wash contaminated clothing before reuse P370 In case of fire: P371 In case of major fire and large quantities: P372 Explosion risk in case of fire P373 DO NOT fight fire when fire reached explosives P374 Fight fire with normal precautions from a reasonable distance P375 Fight fire remotely due to the risk of explosion P376 Stop leak if safe to do so P377 Leaking gas fire: do not extinguish, unless leak can be stopped safely P378 Use … for extinction P380 Evacuate area P381 Eliminate all ignition sources if safe to do so P390 Absorb spillage to prevent material damage P391 Collect spillage P4** Storage Precautionary Statements P401 Store … P402 Store in a dry place S8 P403 Store in a well-ventilated place S9 P404 Store in a closed container S7 P405 Store locked up S1 P406 Store in corrosive resistant / … container with a resistant inner liner P407 Maintain air gap between stacks / pallets P410 Protect from sunlight P411 Store at a temperature not exceeding … oC/ ..oF P412 Do not expose to temperatures exceeding 50 oC / 122 oF
P413 Store bulk masses greater than …kg/ …lbs at temperatures not exceeding ..oC / oF
P420 Store away from other materials P422 Store contents under … P5** Disposal Precautionary Statements P501 Dispose of contents / container to …
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The old Risk Phrases under CHIP Regulations R1 Explosive when dry R35 Causes severe burns R2 Risk of explosion by shock, friction, fire or
other sources of ignition R36 Irritating to eyes
R3 Extreme risk of explosion by shock, friction, fire or other sources of ignition
R37 Irritating to respiratory system
R4 Forms very sensitive explosive metallic compounds
R38 Irritating to skin
R5 Heating may cause an explosion R39 Danger of very serious irreversible effects R6 Explosive with or without contact with air R40 Limited evidence of carcinogenic effect R7 May cause fire R41 Risk of serious damage to eyes R8 Contact with combustible material may
cause fire R42 May cause sensitization by inhalation
R9 Explosive when mixed with combustible material
R43 May cause sensitization by skin contact
R10 Flammable R44 Risk of explosion if heated under confinement
R11 Highly flammable R45 May cause cancer R12 Extremely flammable R46 May cause heritable genetic damage R14 Reacts violently with water R48 Danger of serious damage to health by
prolonged exposure R15 Contact with water liberates extremely
flammable gases R49 May cause cancer by inhalation
R16 Explosive when mixed with oxidizing substances
R50 Very toxic to aquatic organisms
R17 Spontaneously flammable in air R51 Toxic to aquatic organisms R18 In use, may form flammable/explosive
vapour-air mixture R52 Harmful to aquatic organisms
R19 May form explosive peroxides R53 May cause long term adverse effects in the aquatic environment
R20 Harmful by inhalation R54 Toxic to flora R21 Harmful in contact with skin R55 Toxic to fauna R22 Harmful if swallowed R56 Toxic to soil organisms R23 Toxic by inhalation R57 Toxic to bees R24 Toxic in contact with skin R58 May cause long-term adverse effects in
the environment R25 Toxic if swallowed R59 Dangerous for the ozone layer R26 Very toxic by inhalation R60 May impair fertility R27 Very toxic in contact with skin R61 may cause harm to the unborn child R28 Very toxic if swallowed R62 Possible risk of impaired fertility R29 Contact with water liberates toxic gas R63 possible risk of harm to the unborn child R30 Can become highly flammable in use R64 May cause harm to breastfed babies R31 Contact with acids liberates toxic gas R65 Harmful: may cause lung damage if
swallowed R32 Contact with acids liberates very toxic gas R66 Repeated exposure may cause skin
dryness or cracking R33 Danger of cumulative effects R67 Vapours may cause drowsiness or
dizziness R34 Causes burns R68 Possible risk of irreversible effects
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The old Safety Phrases under CHIP Regulations S1 Keep locked up S28i After contact with skin, wash
immediately with plenty of propylene glycol
S2 Keep out of reach of children S28j After contact with skin, wash immediately with plenty of propylene glycol 400 (Roticlean)
S3 Keep in a cool place S29 Do not empty into drains S4 Keep away from living quarters S30 Never add water to this product S5 Keep contents under….. (appropriate
liquid to be specified by manufacturer) S33 Take precautionary measures against
static discharges S6 Keep under….. (inert gas to be specified
by manufacturer) S35 This material and its container must be
disposed of in a safe way S7 Keep container tightly closed S36 Wear suitable protective clothing S8 Keep container dry S37 Wear suitable gloves S9 Keep container in a well-ventilated place S38 In case of insufficient ventilation wear
suitable respiratory equipment S12 Do not keep container sealed S39 Wear eye/face protection S13 Keep away from food, drink and animal
feedstuffs S40 To clean the floor and all objects
contaminated by this material, use….. (as specified by the manufacturer)
S14 Keep away from ….. (incompatible materials to be indicated by the manufacturer)
S40a To clean the floor and all objects contaminated by this material, use plenty of water
S14a Keep away from acids, alkalis, heavy metal salts and reducing substances
S40b To clean the floor and all objects contaminated by this material, use diluted alkaline solution
S14b Keep away from reducing substances (e.g. amines), acids, alkalis and heavy metal compounds (e.g. activators, drying agents, metallic soaps)
S40c To clean the floor and all objects contaminated by this material, use iodized active carbon
S15 Keep away from heat S41 In case of fire or explosion do not breathe fumes
S16 Keep away from sources of ignition – no smoking
S42 During fumigation/spraying wear suitable respiratory protective equipment (appropriate wording to be specified by the manufacturer).
S17 Keep away from combustible material S42a During fumigation wear suitable respiratory equipment
S18 Handle and open container with care S42b During spraying use suitable respiratory equipment
S20 When using do not eat or drink S43 In case of fire, use….. (in the space indicate the precise type of fire fighting equipment. If water increases the risk, add ‘Never use water’)
S21 When using do not smoke S43a For extinguishing, use sand, earth, powder or foam
S22 Do not breathe dust S43b Never use water S23 Do not breathe gas/fumes/vapour/spray
(wording to be specified by the manufacturer)
S45 In case of accident or if you feel unwell, seek medical advice immediately (show the label where possible)
S23a Do not breathe vapour/aerosol S46 If swallowed, seek medical advice immediately and show this container or label
S23b Do not breathe gas/vapour S47 Keep at a temperature not exceeding…oC (to be specified by the manufacturer)
S23c Do not breathe gas/vapour/aerosol S48 Keep wet with….. (appropriate material to be specified by manufacturer)
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S23d Do not breathe vapour S48a Keep wet with water S23e Do not breathe aerosol S49 Keep only in the original container S23f Do not breathe gas S50 Do not mix with….. (to be specified by
manufacturer) S23g Do not breathe smoke S50a Do not mix with peroxide activators and
reducing agents S24 Avoid contact with skin S50b Do not mix with acids S25 Avoid contact with eyes S50c Do not mix with alkali S26 In case of contact with eyes, rinse
immediately with plenty of water and seek medical advice
S50d Do not mix with other chemicals
S27 Take off all contaminated clothing immediately
S51 Use in only well ventilated areas
S28 After contact with skin, wash immediately with plenty of….. (as specified by the manufacturer)
S52 Not recommended for interior use on large surface areas
S28a After contact with skin, wash immediately with plenty of water
S53 Avoid exposure – obtain special instructions before use
S28b After contact with skin, wash immediately with plenty of water and soap
S56 Dispose of this material and its container to hazardous or special waste collection point
S28c After contact with skin, wash immediately with acetic acid 3% and plenty of water
S57 Use appropriate container to avoid environmental contamination
S28d After contact with skin, wash immediately with polyethylene glycol, followed by plenty of water
S59 Refer to manufacturer/supplier for information on recovery/recycling
S28e After contact with skin, wash immediately with polyethylene glycol, followed by plenty of water
S60 This material and its container must be disposed of as hazardous waste
S28f After contact with skin, wash immediately with plenty of a 1:1 solution of polyethylene glycol:ethanol
S61 Avoid release to the environment. Refer to special instructions/safety data sheets
S28g After contact with skin, wash immediately with plenty of cuprous sulphate solution, 2%
S62 If swallowed, do not induce vomiting, seek medical advice immediately and show this container or label
S28h After contact with skin, wash immediately with plenty of lutrol
S63 In case of accident by inhalation; remove casualty to fresh air and keep at rest
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13. BIOLOGICAL SAFETY
There is a large amount of literature associated with Biological Safety which is beyond the scope of this Safety Handbook. It is the responsibility of the research group involved to check the safety of all biological experiments they are involved in and to register the appropriate risk assessment and GMO forms with the Biological Safety Committee.
The Department is only equipped for work with low hazard Biological materials. It is not registered for work with Genetically Modified Plants, Genetically Modified Animals, Plant Pathogens, or Human Pathogens.
All work involving living organisms (including bacteria, mammalian cell lines, yeast, insects, plants), or biological fluids, tissues, or samples (including blood, plasma, urine) requires approval from the Departmental Biological Safety Committee.
The Biological Safety Committee oversees all aspects of the biological health and safety of staff, students and visitors within the Chemistry Department, and of the impact of the Department’s operations on the wider environment.
The Departmental Biological Safety Officer (BSO) is Dr. Richard Turner ext. 63936.
Anyone involved in experiments using animal or human tissue, fungi, micro-organisms etc. must consult with their Principal Investigator and ensure that the work is registered with the Biological Safety Committee. Similarly anyone undertaking molecular biology and expressing recombinant proteins must check that they are working within the allowed guidelines.
It is the responsibility of the individual PIs to ensure that any risk arising from their work is adequately controlled, and that anyone entering their laboratories (including visitors, contractors, cleaners, and maintenance teams) is informed of such risks and the necessary control measures. Before starting work with any biological material you must:
1. Carry out all necessary risk assessments for your work (or read the existing risk assessments) and ask your Supervisor about anything you do not understand or are unsure about
2. Receive all training necessary to ensure safe working. These are provided by or arranged through your research group and other courses are available through the University Safety Office - see http://www.training.cam.ac.uk/ohss/theme)
'a micro-organism, cell culture or human endoparasite, whether or not genetically modified, which may cause infection, allergy, toxicity or otherwise create a hazard to human health'.
Most biological agents are micro-organisms, among which are bacteria, viruses, fungi and parasites (e.g. malaria, or the microscopic developmental stages of larger parasites). A micro-organism is defined as ‘a micro-biological entity, cellular or non-cellular, which is capable of replication or of transferring genetic material, and includes a virus, a viroid, and an animal or plant cell in culture’. Naked DNA, oligonucleotides, synthetic DNA, plasmids or liposomes are not considered to be micro-organisms. In some cases, such as prions, proteins themselves may be biological agents.
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13.1.2 Hazard Groups
Biological agents are classified into four Hazard Groups based on their pathogenicity to humans, hazard to users, transmissibility into the wider community, severity of any resulting disease and availability of treatment.
Hazard Group 1: A biological agent unlikely to cause human disease.
Hazard Group 2: A biological agent that can cause human disease and may be a hazard to employees; it is unlikely to spread to the community and there is usually effective prophylaxis or treatment available.
Hazard Group 3: A biological agent that can cause severe human disease and presents a serious hazard to employees; it may present a risk of spreading to the community, but there is usually effective prophylaxis or treatment available.
Hazard Group 4: A biological agent that causes severe human disease and is a serious hazard to employees; it is likely to spread to the community and there is usually no effective prophylaxis or treatment available.
Work in the Department is permitted only with Hazard Group 1 (HG1) organisms. Hazard Groups 2, 3 and 4 comprise human pathogens.
13.1.3 Genetically Modified Organisms
The primary piece of legislation that applies to the use of genetically modified organisms in the workplace (The Genetically Modified Organisms (Contained Use) Regulations 2014) and is available to download at http://www.legislation.gov.uk/uksi/2014/1663/made. Contained use includes the actual process of genetic modification. It also includes any use of the constructed GMO including storage, transport, destruction and disposal. For example, while laboratory workers will be involved with constructing and using GMOs, those involved in commercial disposal of waste (containing GMOs) also need to comply with the Regulations. Class: Contained uses are classified into one of four classes, based on the risk that the contained use presents to human health and the environment. These are referred to as class 1 (no or negligible risk), class 2 (low risk), class 3 (moderate risk) and class 4 (high risk). The contained use class is derived from the outcome of the risk assessment and is only applicable to GMMs and is not used for larger GMOs. Guidance is available here: http://www.hse.gov.uk/biosafety/gmo/acgm/acgmcomp/part2.pdf
Work in the Department is registered only with GM Activity Class 1 organisms. Other useful information about GMOs can be found at http://www.hse.gov.uk/biosafety/gmo/index.htm
13.1.4 Authorisation to Work
Any work other than with HG1 or GM Activity Class 1 organisms will require further assessment and may need additional licensing or authorisation.
You must first consult with the Biological Safety officer if you wish to work with any of the following:
• Potentially pathogenic organisms, or samples that may contain them • Plant or animal pathogens • Tissues or cells in culture • Human tissues or fluids • and anyone who is working with micro-organisms or viruses for the first time,
Specific licences may be required (e.g. from the Human Tissue Authority or DEFRA) and certain types of work will require HSE notification. The department does not currently hold a licence from the Human Tissue Authority and any work involving human tissue should be planned well in advance in consultation with the BSO. The departmental safety page has a link to the University Safety Office
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HTA page http://www.safety.admin.cam.ac.uk/subjects/biologicals/human-tissue-act which has more information including FAQs. Plant or animal pathogens that are not a hazard to human health, but that pose a hazard to animals or the environment must also be correctly handled and contained. Guidance is provided by the following HSE documents:
Approved list of biological agents - http://www.hse.gov.uk/pubns/misc208.pdf
Management and operation of microbiological containment laboratories http://www.hse.gov.uk/biosafety/management-containment-labs.pdf
It is important to note that handling tissues or secretions e.g. blood and urine, always carries a risk of infection. Guidelines on working with tissues and cells in culture are available at http://www.safety.admin.cam.ac.uk/files/hsd195b.pdf.
13.2 Containment Levels
As well as the list of biological agents falling into each hazard group, the Advisory Committee on Dangerous Pathogens (ACDP) publication entitled 'Categorisation of biological agents according to hazard and categories of containment' also provides guidance on the measures that must be taken to work safely with the agents in each Hazard Group and to 'contain' these agents. These are known as 'Containment Levels'. In general, agents falling into Hazard Group 1 must be handled at Containment Level 1; those falling into Hazard Group 2 must be handled at Containment Level 2 etc.
Each laboratory where biological work is being conducted is assigned a certain Containment Level (CL1 to CL4) depending upon the infrastructure in place (layout, facilities, procedures, and security) which must be sufficient to contain any hazard posed by the work. Most of the laboratories in the Department of Chemistry are suitable only for Containment Level 1 (CL1) work. Any experiments requiring a higher Containment Level must be evaluated accordingly to determine whether the necessary requirements can be met in order to assign CL2 classification. Work requiring facilities beyond CL2 is not permitted.
Guidance on avoiding confusion over the different classification systems for Hazard Groups, GM organisms, and Containment Levels is given in the Safety Office leaflet – “The Numbers Game”. https://www.safety.admin.cam.ac.uk/system/files/hsd106b.pdf
13.3 Risk Assessment Each research project must be assessed with respect to the use of:
1. Biological Agents,
2. Genetically Modified Organisms (GMOs) including Genetically Modified Micro-organisms (GMMs)
Before commencing a project involving any biological material, a hazardous substance risk assessment and a biological risk assessment must be carried out and copies given to the BSO after being pre-checked. It is essential that the risk assessment is received and approved before work starts. If the work involves genetically modified organisms, it must also be assessed under the Genetically Modified Organisms (Contained Use) Regulations 2014 using the relevant GMO form, and submitted to the Biological Safety Committee for approval before work is commenced. The assessment must take account of risks to human health and risks to animals, plants and the environment. This is a legal requirement. No work may commence without the approval of the Committee. Biological Risk Assessments require one of three forms which can be downloaded from the Safety pages of the Departmental website:
1. COSHH form – for any biological work that does not involve genetically modified organisms
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2. GMO RA (short form) – for any genetically modified organism (GMO) work involving disabled E. coli systems
3. GMO RA (long form) – for any genetically modified organism work involving other biological organisms (e.g. yeast, C. elegans)
If you are unsure which form is appropriate, please contact the Departmental Biological Safety Officer for guidance.
13.4 Important Practical Safety Procedures – Essential Reading It is essential that the guidelines given below are adhered to when working with Biological material. Each Research Group should incorporate these procedures into their Local Laboratory Rules and/or Laboratory Management and Safety Plan
1. The laboratory should be easy to clean. Bench surfaces should be impervious to water and resistant to acids, alkalis, solvents and disinfectants
2. Effective disinfectants should be available for immediate use in the event of spillage 3. If the laboratory is mechanically ventilated, it is preferable to maintain an inward airflow while
work is in progress by extracting room air to atmosphere 4. All procedures should be performed so as to minimise the release of organisms and the
production of aerosols. Flasks of cultured micro-organisms should be sealed with a foam or non-absorbent cotton wool bung where possible
5. Cultures grown in flasks should generally not exceed 25% of their container volume 6. The laboratory door should be closed when work is in progress 7. Laboratory coats or gowns should be worn in the laboratory and removed when leaving the
laboratory suite 8. Personal protective equipment, including protective clothing, must be:
1. Stored in a well-defined place 2. Checked and cleaned at suitable intervals 3. When discovered to be defective, repaired or replaced before further use
9. Personal protective equipment which may be contaminated by biological agents must be: 1. Removed on leaving the working area 2. Kept apart from uncontaminated clothing 3. Decontaminated and cleaned or, if necessary, destroyed
10. Eating, chewing, drinking, taking medication, smoking, storing food and applying cosmetics is forbidden
11. Mouth pipetting is forbidden 12. The laboratory should contain a suitable basin or sink that can be used for hand washing 13. Hands should be decontaminated immediately when contamination is suspected and before
leaving the laboratory 14. Bench tops should be cleaned after use 15. Used glassware and other materials awaiting disinfection should be stored in a safe manner.
Pipettes, for example, if placed in disinfectant, should be totally immersed 16. Contaminated materials whether for recycling or disposal, should be stored and transported in
robust and leak-proof containers without spillage 17. All waste material should be held safely and disposed of regularly by appropriate means 18. Accidents and incidents should be immediately reported to and recorded by the person
responsible for the work or other delegated person 19. Spillages must be reported. The report should detail the location of the spillage, the organism
involved, and the method of decontamination.
Further information on ACDP and HSE guidelines for working with biological agents can be found on the Health and Safety Executive website:
• Approved list of biological agents: http://www.hse.gov.uk/pubns/misc208.pdf
13.5 Biological Waste Each research group must have appropriate procedures in place for the disposal of any biological waste generated, via disinfection/chemical inactivation, autoclaving, or incineration as appropriate (see below). There must also be the necessary facilities for regular routine disinfection and cleaning of equipment or work areas. Details about disinfectants used within the group, together with a Safe Operating Procedure (SOP) of their correct use should be provided.
General Guidelines for waste disposal:
1. Contaminated plastic ware, plates, gloves, paper, tips and pipettes (in a suitable rigid container) should be placed in the designated Biological waste bin and autoclaved.
2. Large volumes of liquid waste should be decanted and disinfected with an appropriate disinfectant (e.g. Virkon at the correct dilution) and discarded via the sinks specifically designated for biological waste.
3. Tubes containing less than 10% liquid can be placed straight into the biological waste bin to be autoclaved. Ensure the lids are loosened slightly so that they do not burst when autoclaved.
4. Non-standard waste items may require specialist procedures (e.g. incineration or disposal via a specialist waste contractor). Please contact the BSO.
Procedures must also be in place to meet any foreseeable spillage or release, including emergency containment and cleaning requirements. Further information is available in the University Safety Office document “Disposal of Biological/Clinical Laboratory Waste”: http://www.safety.admin.cam.ac.uk/files/hsd027b.pdf
13.6 Registration and Training
All researchers involved with Biological work must be listed on their group’s “biological worker database” form kept on record by the Department. This must be updated termly.
It is the responsibility of individual PIs to ensure that all members of their groups are provided with appropriate Biological Safety Inductions, training and information, with regards to experiments they intend to conduct and also those being performed by others around them. Training must be provided by persons with suitable knowledge and experience of the biological techniques and associated safety issues involved. If training is provided externally via collaborators in other departments or institutes, details of these labs, the trainers, and training content is required by the Biological Safety Committee (BSC).
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14. IONISING AND NON-IONISING RADIATION
14.1 Ionising Radiation The University of Cambridge is legally responsible for compliance with the requirements of the Ionising Radiations Regulations 2017 (IRR17), and The Environmental Permitting Regulations 2016 (EPR 2016) with the associated Certificates issued by the Environment Agency. The Department has a statutory requirement to appoint Radiation Protection Supervisors (RPS), who carry out tasks on behalf of, and report ionising radiations safety issues to, the Head of Department. As part of its radiation management and operational activities, the Department will consult the Radiation Protection Advisor (RPA) or Radiation Waste Advisor (RWA), as necessary, to ensure that the RPS are able to perform their role.
The Department is committed to keeping doses from work involving ionising radiation to as low as is reasonably practicable (ALARP).
Before commencing any work with ionising radiation or radioactive material the relevant RPS must be informed and the necessary arrangements made for registration with the University Radiation Protection Service.
Name Extn. No. Sector
Dr Richard Turner 63936 Lead / Co-ordinating RPS
Dr Chiara Giorio 36392 Sealed sources RPS
Dr Andrew Bond 36352 X-ray Diffractometer RPS
14.1.1 Sealed Radioactive Sources Sealed sources are subject to specific management arrangements as set out in the RPS’s Source Management Plan.
If you are considering obtaining a sealed radioactive source for use in your research, please contact the DSO before proceeding. All purchase orders for sealed radioactive sources must be countersigned by the RPS and the DSO.
Before any source is used in a new experimental procedure, a complete risk assessment must be completed by the user and signed off by the RPS (Dr Chiara Giorio). The user must also be authorised to use sealed radioactive sources by the RPS and it is Departmental policy that they should also attend the ‘Safe Use of Radioactive Substances – Core Training’ delivered by the University Occupational Health and Safety Service (OHSS) (see: http://www.admin.cam.ac.uk/cam-only/offices/safety/training/courses/list.shtml ).
Local Rules for the area (required by the Ionising Radiations Regulations 2017; Safe Systems of Work for the use of individual sources and; written procedures (detailed in experimental handouts) will be developed by the user with the RPS and displayed with the source. All source use must be assessed by Best Available Technique (BAT), in addition to a Risk Assessment. Forms for arrival and movement of sources, and for User Training are available on the Departmental Health and Safety web pages.
14.1.2 X-ray Laboratory
The X-ray laboratory is a restricted radiation work area. Anyone wishing to use the X-ray Laboratory must first consult Dr Andrew Bond, the RPS for the area.
In order to become a registered user of the X-ray Laboratory and prior to using the equipment, users must first receive training in the use of the instrument(s) they wish to access and the associated Local Rules (including the safety systems associated with the oxygen depletion alarms, the pressurised water system, and the radiation safety housings). Once you have undergone training and are
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registered to use the equipment, your University Card will be programmed to permit you access to the facility.
New X-ray equipment requires prior authorisation checks to be carried out by the Department and critical examinations to be completed by the installer prior to the equipment being put into service. Copies of any critical examinations undertaken MUST be given to and retained by the RPS.
14.2 Non-Ionising Radiation
Optical Radiation
14.2.1 Lasers All lasers within the Department must be sited and operated in accordance with current statutory, University and Departmental rules. The Laser Safety Officer (LSO, Dr Mike Casford) keeps a register of all Class 3A, 3R, 3B and Class 4 laser systems, their local rules and laser users.
Anyone authorizing a change to the laser register has to inform the LSO and/or the DSO before that change occurs. Specifically, changes to the register occur when:
• you buy a new Class 3A, 3R, 3B or Class 4 laser system
• you borrow or buy a used Class 3A, 3R, 3B or Class 4 laser from another group/Department/University
• there is a change in the person responsible for the laser system (i.e. a change in Research Supervisor)
• you take a Class 3A, 3R, 3B or Class 4 laser out of use and move it to another lab for storage
• you keep a Class 3A, 3R, 3B or Class 4 laser in use, but move it to another lab
• you bring a Class 3A, 3R, 3B or Class 4 laser marked ‘out of use’ on the register back into use
• you significantly change or make modifications to the laser system which will affect the risk assessment
• a user arrives or leaves
14.2.1.1 Laser Installations and Risk Assessments The LSO must be consulted as early as possible in the planning stage of any Class 3A, 3R, 3B or Class 4 laser installation. Do not start using a new system without the consent of the LSO. Similarly, if a Class 3 3A, 3R, 3B or Class 4 laser system has been out of use for a number of years, you must consult the LSO before bringing it into use again.
If a setup is used that is significantly different from existing ones, a new risk assessment has to be carried out in consultation with the Research Supervisor and the LSO.
Laser Risk assessments for all experimental setups involving lasers have to be updated on an annual basis.
A Local Rules document listing the properties of the lasers, the users associated with a particular setup, the main rules for working and contingency plans, has to be stored in a folder on the door of the lab.
Laser Risk Assessment forms are available on the Departmental Health and Safety web pages.
For details regarding the safe use of lasers, refer to the University’s Safety Office ‘Safe Use of Lasers’. The LSO is there to help with all questions regarding laser use and safety.
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14.2.1.2 Users Anyone wishing to use a laser must first consult the LSO.
Before using lasers, users have to undergo suitable training (normally arranged by the Research Supervisor) as decided on the basis of risk assessment and have to be aware of the hazards involved. Laser safety courses are run by the Health and Safety Office. Users who have had laser safety training before joining the Department have to provide details of the course to the LSO and/or DSO, if that course took place less than three years ago, otherwise they have to take a refresher course.
14.2.1.3 Incidents / accidents All accidents and incidents involving lasers must be recorded using the accident, dangerous occurrence and incident report form and inform the LSO and/or the DSO, who will report it to the Health and Safety Office.
Do not use the equipment until an investigation has been carried out to establish the cause of the incident/accident.
If there is a suspected injury to the eye, consult Occupational Health, who will make an assessment and arrange any necessary referrals.
If an injury is confirmed, the injured person should see a specialist ophthalmologist preferably within 24 hours of the accident. Do not drive.
If the accident occurs outside the normal working hours of Occupational Health, the injured person should attend the Emergency Department of Addenbrooke’s Hospital, where a specialist ophthalmologist should be available for consultation.
Take details of the laser beam with you to the Emergency Department’s Accident & Emergency; namely its wavelength (as this determines which part of the eye has most likely suffered damage), power/energy per pulse and pulse duration.
14.2.1.4 Safe Practice The following text is a condensed version. For more details refer to the University’s Safe Use of Lasers document:
Class 3B and Class 4 laser systems are used in controlled laser areas with access restricted to authorized users. Contact details for access/emergency are provided on a notice on the lab door.
Damage to sight can occur if a laser beams falls on a person's eye, whether directly or by reflection from a polished surface. There is a special risk if the radiation is invisible, e.g. infra-red. Powerful lasers can produce cataracts in the eye, as well as retinal damage.
All in-use lasers and optics have to be secured to a suitable optical bench. Lasers must not be moved when switched on. Researchers must take special care when moving tools, optical components or other objects in or near the beam, so as not to cause reflected beams to enter their own or other people's eyes. Do not wear anything reflective (watches, jewelry, belts) and take special precautions when using reflective tools. Tie up long hair, as stray reflections from hair have the potential to damage the eye. Do not assume that it is safe to look at a laser beam on a diffusively reflecting surface like a sheet of paper or a lab wall as there is likely to be some degree of specular reflection.
Enclose all laser beams as far as practicable. While it is easy to align open systems, this is not a sufficient reason for not enclosing the laser beams. Any open beams must be justified in the risk assessment. Any optical components, enclosures and shields must be firmly fixed in place. Avoid running beams across walkways. Plan your experiments with this in mind.
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14.2.1.5 Non-beam hazards The non-beam hazards associated with use of the laser and the laser process must be considered when assessing risks.
The use of lasers or laser systems can present an electric shock hazard. Exposures can occur during laser set-up or installation, maintenance and service, where equipment protective covers are often removed to allow access to active components as required for those activities.
Large inefficient lasers require water-cooling. The combination of high voltage and water is potentially very hazardous.
Electric equipment should generally be installed at least 250 mm above the floor to reduce electric risk in the case of flooding. Optical tables, lasers, and other equipment should be well electrically grounded. Enclosure interlocks should be respected and special precautions taken during troubleshooting.
Lasers may create chemical, mechanical, and other hazards specific to particular installations. Chemical hazards may include materials intrinsic to the laser, such as beryllium oxide in argon ion laser tubes, halogens in excimer lasers, organic dyes dissolved in toxic or flammable solvents in dye lasers, and heavy metal vapors in helium cadmium lasers, or generated by the laser process (e.g. fumes). Hazards caused by substances used or generated by the laser must be considered in assessing the risks. Also, solvents are to be used with care as many are flammable.
There are a variety of hazards associated with gases. Even gases that are not normally harmful, such as nitrogen, can cause asphyxiation in sufficient concentrations. Gases may also be toxic, carcinogenic, flammable and explosive. As well as the usual hazards associated with a particular gas, a compressed gas is potentially extremely hazardous due to the high pressure under which it is kept. Cryogenic coolants may cause asphyxiation in confined spaces, so adequate ventilation is necessary. Care should be taken to prevent skin burns; protective clothing and visor should be worn.
Mechanical hazards include moving parts in vacuum and pressure pumps; implosion or explosion of flash lamps, plasma tubes, water jackets, and gas handling equipment.
Class 3B and 4 lasers may present a fire hazard, which requires beam stops and enclosures to be made of appropriate material and cooled if necessary if enclosure materials are likely to be exposed to irradiances exceeding 10 watts/cm2.
Laser safety tips
• Locate beam at waist level or below. Do not place beam at eye level.
• Enclose as much of the beam as possible.
• Don’t direct beam toward doors or windows.
• Use surfaces that minimize specular reflections.
• Locate controls so that the operator is not exposed to beam hazards.
• Make sure warning/indicator lights can be seen through protective filters.
• If you can see the beam through your laser eyewear, you are not fully protected.
• Don’t wear watches or reflective jewellery around Class 3B or 4 lasers.
• In reality, all interlocks are defeatable. The best defence is good understanding of the hazards.
14.2.2 Ultraviolet radiation Ultraviolet (UV) sources are used in a variety of equipment and can be hazardous to the eye and skin. The risks to health from artificial sources of UV can be much higher than from naturally occurring UV. Typical levels of UV may be many times higher than that of the sun and include harmful wavelengths that are normally filtered by the atmosphere. Consequently, precautions should be taken to shield the
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source of radiation. It is vital to have in place control measures to limit exposure to the eyes and skin and to prevent cumulative exposure. The precautions needed will depend upon the risk assessment. Users must be aware of the possible consequences of exposure and the protective measures which need to be followed to avoid exposure.
UV light boxes (‘transilluminators’) are commonly used in molecular biology laboratories for a number of purposes including the visualisation of eithidium bromide intercalated nucleic acids separated under electric current in electrophoretic gels. These devices typically have peak outputs at 254 or 312 nm, well within the UV-C and UV-B regions that are biologically active and capable of damaging skin. The UV light emitted from transilluminators has been clearly identified as a potentially significant occupational hazard for many laboratory workers.
Instances of minor and more significant skin damage have been reported. Fortunately, the hazards can be easily controlled, through proper training and the use of quite basic personal protective equipment (full face shield, in good condition, and, supplies of disposable gloves).
The following recommendations have been issued by the Health and Safety Office:
• Recognize that the UV light emitted from transilluminators is harmful, and over-exposure can cause serious skin and eye damage. Locate UV boxes in low occupancy areas, preferably in separate rooms, alcoves, or behind a curtain when inside a larger occupied lab. Portable handheld units generally have lower output than fixed bench units, but still offer the potential for harm.
• The basic tenets of radiation protection – time, distance, and shielding – apply to UV light as well as ionising radiation. Minimize contact times with UV light sources; maximize distance by working at arms’ length and avoiding stooping over the work surface, and use shielding and personal protective equipment.
• When purchasing a new transilluminator, only consider units with retractable or hinged plastic safety covers since these can filter a significant amount of biologically-active UV. Since such intense exposure to UV light degrades plastic over time, it is important to replace these covers every few years and even sooner if discolouration or cracking is observed.
• Keep basic personal protective equipment available and ready for use at light box work stations. This should include a full-face shield designed for UV B&C filtration (typically polycarbonate) and several different sizes of disposable gloves. Goggles do not provide sufficient protection. Wearing ordinary prescription or safety glasses under the face shield provides even greater ocular protection, and a full buttoned lab coat provides good arm, wrist, upper chest, and neck protection. Since protective equipment is least likely to be worn when it is damaged or soiled, ensure that equipment is available and kept in good condition.
• Users should wipe down UV light box work surfaces and control knobs after each use. Despite regular cleaning, the routine use of ethidium bromide in gels and electrophoresis running buffers means that contamination from this known mutagen should be anticipated and UV light box work areas approached accordingly. If the laboratory also uses radioactive material in nucleic acid work, this kind of contamination should also be expected and dealt with appropriately.
• Laboratory workers are reminded of the symptoms of UV over-exposure (i.e. skin reddening, sandy or gritty feeling in the eyes – conjunctivitis), and are encouraged to obtain medical attention and report the incident to their Supervisor and the DSO as soon as possible. Since these symptoms are often delayed by several hours, making prompt diagnosis and medical treatment more difficult, prevention is especially important.
For further information on the use of UV sources, please refer to the University’s guidance document ‘Safe Use of Artificial Sources of Ultraviolet Radiation’ available to download at: http://www.admin.cam.ac.uk/cam-only/offices/safety/radiation/nonir/ultraviolet/uvhsd014r.pdf .
14.2.3 Electromagnetic Fields There are well established and understood short term adverse effects at high levels of exposure to electromagnetic fields and the University has a duty to protect staff students and others affected by the work.
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The International Commission on Non-Ionising Radiation Protection (ICNIRP) provides guideline limits based on preventing these effects. There are specific regulations regarding EMF safety that have been implemented.
14.2.3.1 Nuclear Magnetic Resonance (NMR) NMR equipment and the NMR service are restricted work areas. Anyone wishing to use certain research group equipment must consult Duncan Howe or Andrew Mason of the NMR Service.
15. GAS SAFETY
15.1 Gas Balloons Gases are used in a variety of experiments throughout the department often in balloons. There is a potential health and safety concern particularly when inflated balloons are transported from a cylinder in the corridor to the lab fume cupboard, when checking for experimental safety and in the case of an emergency. Therefore, to mitigate against the health and safety concerns of not knowing the identity of the gas or its hazard, balloons have been standardized in terms of colour and hazard label. When planning an experiment, the balloon must be matched with the gas hazard; this requires the gas to be categorised into one of three groups; flammable, toxic and safe. The figure below shows commonly used gases with their respective balloon colour and hazard symbol. Red balloon = flammable Yellow balloon = toxic Green balloon = safe
Hydrogen Carbon monoxide Carbon dioxide
Nitrogen Argon
Oxygen Figure 8: Colour and hazard labelled standardised balloons Gases can be categorised into three groups by referring to their safety data sheet (SDS). If there is no conclusive category, it is best to err on the side of safety and use the yellow balloon. The risk assessment for the experiment should also consider the gas containment in a balloon. A fully inflated balloon has a capacity of 0.5 cubic feet = 14 litres. Average human lung capacity is 6 litres.
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15.2 Compressed Gas Cylinders Gas cylinders can be dangerous if not handled and used properly. Do not attempt to handle any compressed gas cylinders until you have received specific training to do so.
15.2.1 Gas Cylinder Hazards Gas cylinders present the following hazards:
• The high pressures inside compressed gas cylinders represent a huge quantity of stored potential energy. If damaged, they can behave like rockets. A wayward cylinder can pass through the wall of a building.
• At high temperatures, the pressure build-up inside a cylinder can result in explosion. Some cylinders will explode at temperatures around 50 °C.
• Full size gas cylinders are very heavy and awkward to handle. Accidents involving falling cylinders often result in broken bones to the foot, whilst attempting to catch a falling cylinder can also cause serious injury. Gas cylinders should only be moved on a special cylinder trolley and never with the regulator attached. If you lose control of the cylinder whilst you are moving it then let it go. Do not try to catch it.
It should also be remembered that flammable gases can ignite or explode; oxygen and other oxidising gases (e.g. chlorine) will support burning; asphyxiant gases (such as nitrogen, argon, helium and carbon dioxide) displace oxygen from the air and can cause death through suffocation; toxic gases can poison and cause death while corrosive gases can cause damage to the eyes and/or respiratory system.
15.2.2 Planning Work with Gas Cylinders • Ensure that you are aware of any special hazards associated with the gases you are planning
to use. Are they flammable, oxidising agents, poisonous, corrosive? Always use the least hazardous gas that is experimentally viable for your work.
• If you are proposing to use any highly toxic gas you must first consult your Supervisor and complete a written hazardous substance risk assessment before commencing work. You should also consult your Floor Technician before starting an experiment involving a toxic or corrosive gas.
• Remember that many gases have a high solubility in liquid and it may be necessary to remove an excess of the gas after a reaction by blowing through with air or nitrogen in a fume cupboard.
• If you expect to use a poisonous gas or a mixture containing a poisonous gas at a concentration near to or above the Workplace Exposure Limit (WEL) then you must consult the DSO before you commence work. Special equipment and procedures will be necessary for your work.
• Consideration should be given to monitoring equipment to check for safe levels of gases in the air including oxygen monitors.
• Emergency procedures must be in place. What will you do if a gas cylinder leaks or vents? Do you need any special equipment? How will you ensure that your emergency procedures are known and understood by other workers in the lab?
15.2.3 Starting Work with Gas Cylinders
• Cylinders should always be stored, transported and used in an upright position.
• While in the laboratory, cylinders must be securely held in trolleys, metal stands or bench clamps.
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Regulator Components
A – Outlet (low pressure) gauge B – Pressure relief valve C – Cylinder (high pressure) gauge D – Captive pressure adjusting screw (Captive PA) E – Inlet blanking nut (HP nut) F – Regulator outlet G – Nut – with thread H – Bull nose stem - regulator inlet
Figure 9: Double gauge six port regulator components
• Gas cylinders must always be used with the correct gas regulators and adaptors. Regulators are inspected annually and should carry a valid inspection tag or label. If an inspection tag is not present or is out of date, the regulator should not be used but returned to the Mechanical Workshop. Regulators which have failed the annual inspection, MUST NOT BE USED.
• Gas regulators should be replaced or exchange-refurbished every 5 years as the seals and filters deteriorate. Spontaneous failure of regulators is rare, but those fitted to carbon dioxide cylinders have a very poor track record.
• ‘Snifting’ – clearing the cylinder inlet prior to fitting the regulator by releasing a little gas in order to expel any dust from the connection – is a potentially high risk activity due in part to gas types and pressures and should only be attempted by competent personnel. It is recommended that a visual inspection of the bottle inlet is conducted prior to fitting the gas regulator. Any dirt or contaminants should be removed with nitrogen or dry air if necessary. Snifting should never be attempted with hydrogen due to the real risk of auto-ignition because hydrogen, unlike most other gases, heats up when it is released from a high pressure vessel. It should be borne in mind that industry guidance no longer recommends snifting.
• It is not best practice to use lubricants or PTFE tape in gas lines. Lubricants and standard PTFE tape MUST NEVER be used in oxygen or oxidising gas lines. Oxidising gases react violently with these substances and may explode or ignite. While oxygen compatible PTFE tape is available such as Green Oxygen Thread Seal Tape, it is still not best practice to use such tape.
• A regulator should be used only to regulate the pressure of the gas from a cylinder – not to turn the supply on and off. The main cylinder valve should be closed when the cylinder is not in use, and always remember to close the valve when the cylinder is finally empty.
• Never connect a gas cylinder or compressed air directly to glass apparatus; always use a safety bottle (trap or ‘plus and minus’ bottle).
• Systems with special requirements involving the use of non-standard gas regulators, reducing and/or control valves should carry very clear labels indicating what is being controlled and the direction of control if relevant.
• When techniques involve gas pressure outside the general experience and expertise of the Department expert help should be sought.
• Any gas handling system of more than a temporary nature should have, fixed nearby, a diagram showing its functions. The relationship of the controls to the diagram must be clear.
• Any apparatus intended to operate at low pressure, but connected to a high-pressure supply, must be separated by a positive closure valve in addition to any flow control and must either be capable of accepting the high pressure or else have a designed bursting feature or other pressure relief valve, set at a safe level.
• Flashback arrestors should be fitted downstream of pressure regulators in flammable gas systems and oxygen systems whether or not they are used together. Heat-activated
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flashback arrestors are preferable to flame-activated ones. When working with acetylene cylinders, a flashback arrestor MUST be fitted to prevent spontaneous combustion arising in the event of a flashback.
• Flammable gas cylinders must not be positioned directly under electrical equipment.
• Do not apply a vacuum to cylinder regulators.
• Check your compressed gas system regularly for leaks with a commercial leak testing solution. Remember, corrosive gases can destroy protective seals over a period of time resulting in leaks or venting.
15.3 Liquefied / Cryogenic Gases Liquefied/cryogenic gases can cause severe cold burns if the liquid is allowed to come into contact with bare skin or eyes. Small volumes of liquid can also evaporate into large quantities of gas and consequently deplete the oxygen in the air.
15.3.1 Low Oxygen Atmospheres Normal ambient air contains an oxygen concentration of approximately 21% by volume, the other main constituents being nitrogen (~78%) and argon (~1%). Atmospheres containing less than 19% oxygen are considered oxygen deficient and are not considered safe to breathe. At concentrations of 12–14% oxygen, the respiration rate increases and judgement is impaired whilst atmospheres containing less than 11% oxygen can result in fainting, subsequent brain damage and death.
Asphyxiation from the lack of oxygen causes swift painless death without prior warning of danger
Great care must be taken in the use of asphyxiant gases such as nitrogen, helium and argon and low-temperature liquefied/cryogenic gases, which displace oxygen from the air. Typical asphyxiant gases cannot be detected by sight or smell and there may be no warning that dangerous levels are building up.
Cryogenic gases each have a characteristic gas expansion factor which can vary from about 400 to about 1400 depending on the gas in question. Nitrogen has an expansion factor of 683 (usually quoted as a 700:1 expansion ratio). This means that a given amount of nitrogen gas occupies a volume which is 683 times greater than the same amount of the liquid. This allows one to calculate the ‘worst case scenario’ for a given cryogenic gas spillage in a given room. If it is possible for a dangerously low oxygen level to result from a spillage then oxygen-monitoring equipment and/or increased ventilation must be provided.
Example Calculation
A 25-litre liquid nitrogen Dewar is spilt in a room of volume 140 m3
Volume of excess nitrogen gas resulting from a 25-litre liquid spill = [(25 x 683)/1000] m3 = 17.1 m3
Assume this excess nitrogen gas displaces 17.1 m3 of air in the room.
Volume of oxygen left in the room (21% of the remaining air) = [(140 - 17.1) x 0.21] m3 = 25.8 m3
Percentage of oxygen left in the room by volume = [(25.8/140) x 100] % = 18.4 %
A figure of 18% has been chosen as a trigger for action because it is a level at which there is no immediate danger to life. When designing experiments, it is acceptable for to be rare occasions when
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the concentration dips to 18%, but this is to be infrequent and for a very short duration. The calculations and a level of 18% can be used to decide whether further control measures shall be installed or whether monitoring is appropriate.
It should be noted that the above calculation does not take into consideration furniture etc. which occupies a percentage of the volume of the room and assumes good mixing of gases so that the oxygen concentration is uniform throughout the room. This may be the case in a room where the air is vigorously mixed, for instance by mechanical ventilation. In a room where air mixing is less vigorous, however, there may be quite a marked vertical concentration gradient. Gases which are significantly denser than air, such as argon, will mix less well than nitrogen, the density of which is very similar to that of air.
When working with cryogenic gases keep in mind at all times that small volumes of liquefied gas will evaporate into large volumes of gas and can consequently deplete the oxygen content of air available to you to breathe resulting in asphyxiation.
Remember: nitrogen, helium and argon cannot be detected by sight or smell and there may be no warning that dangerous levels are building up
When working with asphyxiant and cryogenic gases the following rules should be observed:
• Never work with asphyxiant gases or with cryogenic gases in poorly ventilated areas. Ensure that vessels (Dewars) containing cryogens are only operated in an area that has adequate ventilation.
• When working with cryogenic gases, use only containers which are specially designed for use with such gases. Use proper transfer equipment such as a stainless steel flexible hose, phase separator etc. to prevent splashing or spillage.
• Where possible, do not accompany cryogenic vessels in lifts. Open Dewars must not be transported in lifts.
• Cryogenic equipment must have adequate pressure releases, safety valves and vent lines maintained to prevent the build up of pressure and possible explosion. Do not allow them to become heavily iced over.
• Cryogenic gases can cause severe cold burns if allowed to come into contact with eyes or skin. Protective clothing (leather gloves or equivalent and eye protection) must be worn where there is a risk of splashing cryogenic liquid onto the skin or into eyes and at all times when decanting liquid from a Dewar.
• Liquid oxygen constitutes a further major hazard in that it supports combustion and can cause an explosion.
15.4 Gas Alarms In many areas of the Department where toxic and asphyxiant gases are used, gas alarms systems have been installed. The systems comprise an alarm panel, sensors, beacons and sounders. These systems do not always have a power backup in times of power outages and so will go into alarm when the power is restored. Gas alarm panels show the type of sensor attached. The sensors are located in places where leaks are likely or where escaped gas will accumulate. The sensors also have finite lifetimes and fail to “safety” causing the alarm to go off. Beacons are installed inside and outside of the lab. Where a gas alarm system is present, all room / lab users must know what to do in the event that the alarm sounds. Gas alarms are essential life safety systems and appropriate action must always be taken should the alarm sound.
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16. PRESSURE SYSTEMS AND VESSELS
There are two types of pressure system within the Department:
• Statutory vessels, which exceed 250 bar litres in capacity, such as compressors, autoclaves, pressure cookers, pressurised Dewars and water boilers.
• Research vessels and systems above atmospheric pressure where the vessel, pipework or a combination of both, are purpose built.
A Written Scheme of Examination is required for each of the statutory vessels. Preparing the Written Scheme of Examination is the responsibility of the University’s Insurers, who maintain a register and send an engineer to inspect these according to the Written Scheme of Examination.
Any item of pressure equipment purchased for use should come with Test Certificates and these will be required for evaluation by the Insurance Engineer along with any material certificates for any items manufactured within the Department.
16.1 Research Vessels and Systems Schematics for purpose built systems whether using commercial vessels or in-house manufactured vessels must be evaluated with regard to design and safety considerations.
In house designed vessels should be subject to stress calculation prior to manufacture. The Mechanical Workshop will arrange for the vessels to be pressure tested (at a pressure at least 25% higher than the working pressure) upon completion and obtain a pressure report.
Manufactured vessels should only be used for the purpose they were built for; changing parameters or chemicals requires re-submitting schematics. Do not modify vessels without contacting the Mechanical Workshop.
Do not select a vessel from the shelf and start pressurising assuming it is a tried and tested vessel for the purpose.
16.2 Vacuum and Sub-atmospheric Systems All vacuum systems must be considered hazardous due to the risk of implosion. It is therefore essential that vessels can withstand pressures at least 30% lower than those expected to be generated. Glass vessels including rotary evaporators must be guarded i.e., fitted with protection such as self-adhesive tape, cling-film or plastic netting or be plastic-coated in order to reduce the risk of injury should they implode. All rotary oil vacuum pumps should be fitted with mist/odour filters. Wherever possible, they should be exhausted to the outside. Pumps should be placed on leak containment/spillage trays.
Vacuum systems should also be considered as pressure systems when there is any connection to pressure, including small volumes of gas being introduced, i.e. if the vacuum were to fail they could become pressurised.
16.2.1 Potential High Vacuum Hazards and Schlenk Line Precautions Care should be taken when using vacuum lines. Below are some possible hazards that everyone should be aware of.
1. Explosion - Explosions can occur in a number of ways, including:
a. The use of pressurized gases - High vacuum manifolds are often connected to an inert or reactant gas supply line. You must ensure that the vacuum system is not closed when the gas supply is opened - there MUST be a source of pressure relief such as a bubbler. The pressure must be monitored with either an electronic gauge, manometer or bubbler. Make sure the valve to the pressure reading device is open to the manifold. Always TRIPLE CHECK that the manifold and supply line are connected to pressure relief
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(and your pressure sensor) before opening the gas supply. ALWAYS use an appropriate pressure regulator to avoid opening the line to more than 1 atm of pressure at any time.
b. Condensed gases - Some gases, such as carbon monoxide, oxygen and ethylene, are easily condensed into a liquid nitrogen-cooled trap. If the coolant level drops or you remove the nitrogen Dewar without providing a means of pressure relief, the liquid may convert rapidly back to vapour. For example, 10 ml of liquid CO (b.p. -191.5 °C) corresponds to 6.5 litres of gas. In a vacuum line with an internal volume of 500 ml the internal pressure would be 13 atm, more than enough to shatter the manifold with explosive force.
Leaking manifolds allow air to enter a vacuum system. The liquid nitrogen trap can condense the oxygen into a liquid state. The danger presents itself when the nitrogen either runs dry or the Dewar is removed. The liquid oxygen can quickly form back into gas with enough internal pressure to cause the vacuum manifold system to explode. Although it rarely occurs to that extent (if vacuum lines are well maintained) all lab workers should be aware of the hazard and course of action below.
If you remove a filled nitrogen Dewar from your system and notice liquid inside the trap:
1. Assume it is oxygen – IMMEDIATELY REPLACE THE DEWAR.
2. Turn off vacuum pumps.
3. Place a shield in between you and the Dewar.
4. Slowly release the vacuum and open the system to atmosphere through largest (and closest) ports available.
5. Leave shielded and untouched until all the nitrogen and oxygen has returned to gas form.
c. Runaway reactions - Some reactions can occur violently and evolve large quantities of gas. Stay alert and watch for this situation and always provide for a quick source of pressure relief.
d. Heating a closed system - Never heat a vessel on a closed line without being open to a bubbler.
e. Explosions of glass vacuum lines - have lead to death and serious injuries when used improperly. Always wear your safety glasses to protect your eyes.
2. Implosion - An unseen star crack or stress in a glass manifold can cause a catastrophic failure of the line while under vacuum. Accidentally bumping the line can also cause a failure. While not usually as serious as an explosion, implosions generally involve sharp pieces of flying glass.
Whilst the above discussed a few general hazards associated with high vacuum and Schlenk lines it is not meant to be a comprehensive reference to dealing with or assessing all possible hazards. The exact set-up of a vacuum line will depend on the application and the operating pressure. Figure 10 shows a simplified vacuum-line set-up, typical for synthetic applications. Training from a skilled group member should be obtained before using a vacuum line of any type.
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Figure 10: Standard vacuum-line set-up for synthetic applications
Regardless of the nature of the vacuum line, the following safety procedures should be followed:
• All vacuum systems should be considered hazardous due to the risk of implosion. Glass tubing on the vacuum manifold should be covered by a metal screen or plastic net.
• Never allow the vacuum to be open to the atmosphere while the line is in operation. This will lead to condensation of air/oxygen in the cold trap, which poses a potential risk of explosion. The type of vacuum grease used will depend on the operating pressure and temperature of the system and only the appropriate vacuum grease should be used.
• Always wear thick protective gloves while attaching rubber tubing to the vacuum line. Do not use undue force in attaching rubber tubing (the rubber tubing may be heated with a heat gun and vacuum grease applied to the internal wall at one end in order to make attachment of the tube easier).
• Particular care should be taken in handling Dewars. These will implode if smashed. Dewars should be securely mounted in a steel cylinder.
Special Note: The University is involved in programmes to eliminate the use of mercury as far as possible. The use of mercury-filled bubblers on vacuum-lines is prohibited.
Standard Procedure for Turning On or Off:
• Ensure that no volatile substances are present in the cold trap. If present then the trap should be removed (wearing thick gloves), the material removed, and the trap thoroughly dried in an oven.
• Close the system to the atmosphere.
• Switch on the pump.
• Ensure there are no leaks. If so, the pump should be switched off and the system opened to the atmosphere before continuing.
• Once the full vacuum is established throughout the vacuum line, place the Dewar around the trap and fill with liquid nitrogen.
• Turning off the system is the opposite of the above. Remove the Dewar, turn off the pump, open the vacuum system to the air slowly and remove the trap immediately.
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• Be aware of the risk of explosion in cold traps containing condensed gases e.g. air and ozone.
16.3 Safe use of Pressure Systems When working with pressure systems the following guidelines should be observed:
• Glassware should be inspected for scratches, cracks or defects before each use. Note: normal glassware is not suitable for use in pressurised systems or for systems significantly below atmospheric pressure. Any glassware used for pressure systems should be certified for use.
• Safety shields and safety netting should be used on pressurised systems wherever possible.
• Ensure that the design pressure of any system cannot be exceeded by incorporating a suitable safety device to allow safe release of excess pressure or of vacuum e.g. a bursting disc or relief valve. Safe methods of venting from relief valves used should be used where necessary.
• Make sure nuts are compatible with their bolts and that the bolts are fully through the nuts. Depth of bolts in tapped holes should be at least 1.5 times the diameter.
• Check that bolts in the system are tightened to the correct amount by using a torque spanner. Never over-tighten bolts as they may shear off.
• Screws and bolts should be confirmed as being of suitable strength.
• Always follow manufacturer’s instructions for pipe fittings. Do not mix thread types. If a thread will not engage sufficiently then the threads are not compatible.
• PTFE tape should not be used on parallel threads.
• Ensure that the pressurising fluid or gas mixture you are using is compatible with the seals and vessel material.
• Special care should be taken to ensure that any chemical reaction is assessed to ensure that it does not compromise vessel design.
• Never modify a vessel unless you have it re-tested. Even a small change to the fabric of the vessel can significantly weaken the structure.
• Gauges should be chosen to have at least 25% higher capacity than the maximum working pressure of the system.
• Check the units of the gauges as they can be either bar, psi, kpsi, Pascals, atm, or kgmm-2 or Nmm-2 in H2O or mmH2O. Confusing one with the other can lead to disasters.
• Never take a chance or improvise with a pressure system. Failure can be catastrophic.
• Never direct a jet of compressed air at the human body. This can kill.
1 bar @ 105 Pa @ 14.50 psi @ 0.987 atm @ 750 mmHg (or Torr)
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17. MISCELLANEOUS PRACTICAL ASPECTS
17.1 Glassware and Sharps The most common accidents resulting in injury within the Department occur as a result of handling sharp objects or glass.
Inspect glassware regularly for signs of damage and for flaws. Never use or store defective glassware; return it for repair or discard it. Always discard broken glass into cardboard glass disposal boxes (bench-top or floor standing). All glass disposed in these bins should be free of chemical contamination. Never put broken glass into a general or recycling wastebasket, bin or dustbin.
Never leave needles or scalpel blades lying around on benches or within fume cupboards. Unsheathed/unprotected needles/cannular needles and scalpel blades present a risk of injury and possible contamination from chemicals. Hypodermic needles should not be re-sheathed before disposal and scalpels should not be used without a handle. Reusable needles and blades should be guarded/protected when not in use by the use of rubber bungs or similar methods. Needles should be placed in a tall crystallising pan when in drying ovens. Sharps should always be disposed of in the yellow sharps bins.
17.2 Rubber and Plastic Tubing When setting up apparatus, tubing-to-glass joints should always be secured using uni-clips. Rubber and plastic tubing should be periodically checked and any that is perished or cracked must be replaced. Floods are all too frequent occurrences and can cause considerable damage. Take care when removing rubber tubing from glass; stuck tubing should be cut off.
17.3 Oil Baths Constant temperature oil baths should employ silicone oil/fluid. Heavy paraffin oil and PEG baths should not be used.
For temperatures in excess of 200 °C, it is normally best to use a sand bath, graphite bath, Wood’s metal bath or isomantle. However, the Floor Technician should be consulted in all cases where heating is required in excess of 150 °C prior to starting the experiment.
Solid heating blocks are commercially available and are an excellent alternative to oil baths or other heating methods.
When using oil baths the following guidelines should be followed:
• Prior to use the thermocouple (which is dipped into the oil bath) should be checked to ensure that it is plugged into the stirrer hotplate and securely held in place (otherwise the oil will heat beyond the auto-ignition limit).
• Never mix different types of oil.
• Change the oil if it becomes accidentally contaminated, discoloured or if water is present.
• Never attempt to remove the water by boiling the oil.
All in-house thermostatically controlled CT baths (constant temperature baths) are restricted. However, proprietary heater-stirrers are not restricted and can heat in excess of 300 °C.
Great care must be taken to ensure that the temperature setting used on a stirrer hotplate is compatible with the oil used.
Overheating an oil bath is a common cause of fires within the laboratory
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17.4 Low Temperature Baths The low temperature baths below prevent freezing of oxygen:
System °C
Ethylene glycol / CO2 -15
o-Xylene / N2 -29
Acetonitrile / CO2 -42
Chloroform / CO2 -61
Ethanol / CO2 -72
Acetone / CO2 -77
Methanol / N2 -98
Two types of systems are shown in table above:
• One involves pouring liquid nitrogen (boiling point -196 °C) into a solvent by stirring until slush is formed. The temperature may be maintained by periodically adding nitrogen to maintain the slush.
• The second system involves addition of small lumps of dry ice to the solvent until a slight excess of dry ice coated with frozen solvent remains. Again temperatures can be maintained by periodically adding more dry ice.
17.5 Lifting Equipment (Hoists, Slings, Shackles, Eyebolts and Spreader Beams etc.) All lifting equipment is subject to a 6 or 12 monthly inspection by the University Insurers (the frequency of inspection will depend upon the type of equipment and its use). A central register of all lifting tackle is held by the DSO and as such the DSO must be informed when new lifting equipment is installed. Any lifting equipment, shackles, chains etc. failing these inspections must be replaced or repaired as specified by the Inspector. All lifting equipment must be accompanied by a manufacturer’s test certificate and where required, marked with the safe working load. Copies of the manufacturer’s test certificate must be given to the DSO on delivery.
It is essential that all lifting equipment selected for a lifting operation is suitable for the activity it is to carry out. Factors to be considered in assessing suitability include:
• Type of load being lifted – its nature, weight and shape.
• Risk of the load falling or striking something, and its consequences.
• Risk of the lifting equipment falling or striking something, and its consequences.
• Risk of the lifting equipment failing or falling over while in use, and its consequences.
All lifting operations involving lifting equipment are subject to the requirement to undertake a risk assessment in order to identify the nature and level of risk associated with the proposed lifting operation. Factors to be considered in the assessment of risk are those listed above.
All lifting equipment must be visually checked prior to each use and any defects must be reported to the DSO immediately. The equipment must not be used until the defect has been rectified.
17.6 Ladders A register of all ladders and steps in the Department is kept by the Departmental Safety Technician (DST), who will inspect all items annually or more frequently where appropriate. Any defects will be
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dealt with immediately. Any defects noticed on ladders and steps must be notified to the DST who must also be informed of any new ladders and steps purchased. Only ladders of approved quality (BS EN 131 covering ladders and step ladders constructed from aluminium, steel, plastic or timber, or BS 2037, that covers aluminium ladders, steps and light weight staging (Light Trade minimum, or Class 1 or 2) may be purchased. Domestic grade ladders are not suitable and must be removed from use.
17.7 Fume Cupboards, Microbiological Safety Cabinets (MSCs) and other Containment Devices
17.7.1 Fume Cupboards A fume cupboard is a key protective and control device in laboratories where chemicals are used. It is primarily a protective ventilated enclosure (partial containment device) designed such that hazardous concentrations of quantities of airborne contaminants are prevented from escaping from the fume cupboard into the work room or laboratory by means of a protective air barrier between the user and the materials placed within the enclosure (Figure 11 below).
Figure 11: Formation of protective air barrier
Potentially dangerous or obnoxious fumes are conveyed from the fume cupboard enclosure to an outside discharge point where they can be safely dispersed at low concentrations thereby ensuring that the possibility of forming an explosive or hazardous atmosphere inside the work space is reduced.
The fume cupboard is ventilated by an induced flow of air through an adjustable working opening (namely the sash) which also offers the user some degree of mechanical protection against splashes of substances and flying particles.
If anything interferes with the protective air barrier or the fume cupboard, or disrupts the air flow into and within the fume cupboard, the fume cupboard’s ability to protect the user may be seriously reduced.
The Purpose of a Fume Cupboard Fume cupboards are typically used to prevent or control exposure of the researcher to hazardous chemicals. However, no type of fume cupboard provides total protection and even under ideal conditions some leakage will occur even with a closed sash. If exposure via leakage poses a significant health risk e.g. when working with substances with very low workplace exposure limits or very high acute or chronic toxicity (e.g. toxins or carcinogens) then the use of total enclosure devices such as glove boxes or isolators should be employed rather than fume cupboards.
Fume cupboards are typically used to:
• Prevent or control exposure of laboratory workers to airborne substances hazardous to health and radioactive materials through the capture, dilution and retention of gases, vapours and (non-infectious) aerosols released within the working chamber or enclosure so they do not escape into the laboratory.
• Dilute and discharge or otherwise remove hazardous substances so that air released to the general environment presents no significant human or environmental risk.
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• Dilute flammable gases, vapours or dusts in sufficient air to prevent or minimise the risk of explosion.
• Provide physical protection against spills, splashes and minor fires and explosions.
• Isolate or segregate work activities for reasons of safety, product protection or cleanliness.
• Provide secondary containment in the event of failure of the containing vessels or apparatus and so limit the potential spread of spills of hazardous material.
Fume cupboards must NOT be used:
• For work with biological materials.
• To release especially hazardous chemicals into the atmosphere.
• To capture contaminants generated elsewhere in the laboratory.
• As a store cupboard for equipment, unwashed apparatus, malodorous chemicals or chemical waste and residues.
• To house large items of equipment, whose bulk can cause major air disturbances within the fume cupboard body and so compromise the level of containment.
How to use a Fume Cupboard The degree of protection to a hazardous substance offered by a fume cupboard can be rapidly reduced if the following advice is not followed. It should be noted that no fume cupboard, however well designed, can provide adequate containment unless good laboratory practices are used. Adequate planning and preparation are key. It is important that the fume cupboard limitations are recognised. It may be necessary to use special containment devices such as glove boxes or specialised fume cupboards such as perchloric acid hoods.
• Prior to use confirm that the fume cupboard is suitable for the purpose and is operating satisfactory, i.e. check the on/off controls, operation of sash, audible or visible sash height alarm (where fitted) and light operation.
• Check the airflow gauge/indicator to see whether the fume cupboard is operating above its minimum rate of airflow. In the absence of an airflow indicator, it may be necessary to feel air movement into the cabinet or to check the face velocity.
• Check the gauge on the integral pneumatically actuated fire suppression system (PAFSS) to ensure it is fully pressurised if needed in case of emergency
NB. The fact that a fume cupboard is switched on does not confirm that air is flowing through the system and at the required airflow
• If the fume cupboard is not working correctly report the fault to Maintenance.
• Ensure that the floor area in front of the fume cupboard is unobstructed with furniture or equipment and close any windows or doors which may interfere with the performance of the fume cupboard (air currents and turbulence in the room caused by furniture and other obstructions placed too close to the fume cupboard could affect its performance and containment efficiency).
• Do not position fans or mobile air-conditioners in the room in a manner that will direct airflow across the face of the fume cupboard as this could affect the containment of the cupboard.
• Ensure sufficient room inside the fume cupboard to do what is required. Remove unwanted apparatus and equipment and avoid all unnecessary clutter.
• Where practicable, place everything needed inside the fume cupboard before starting a procedure (this should reduce the number of arm movements into and out of the working aperture, a major cause of fume escape).
• Maintain the protective air barrier for a safe work area by ensuring that a 150 mm wide ‘equipment free zone’ is maintained behind the sash at all times.
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• Avoid using large objects inside the cupboard as these may have an adverse effect on performance and block the rear slots (see Figure 12). If large equipment must be placed inside the fume cupboard, it should be raised approximately 50 mm to allow air to pass beneath the object and placed near the rear of the cupboard taking care not to block the rear slots
Poor placement of large
equipment Good placement of large
equipment
Figure 12: Placement of large objects / equipment within fume cupboards
• Arrange apparatus within the cupboard to allow the operator normal access with the sash in as low a position as possible; and not greater than 0.5 m, and do not position equipment so far back that it obstructs the rear slots.
• Keep the sash lowered whilst an experiment is in progress and the fume cupboard is unattended. Fume cupboards with horizontal sliding panes should be used with the sash all the way down, with as small an open area as possible.
• Where there is the potential for explosion additional shielding must be used.
• Do not put your head inside the fume cupboard enclosure at any time whilst hazardous substances are present.
• Avoid sitting at the cupboard as this restricts mobility in an emergency • Proper use of a fume cupboard does not negate the need for proper Personal Protective
Equipment (PPE). Use suitable PPE (lab coats, gloves, goggles or face shields) at all times when working at a fume cupboard.
• Where possible, chemicals must not be stored in the fume cupboard and where they are, quantities must be kept to a minimum i.e. those in current use.
• Do not leave equipment such as hotplates or stands in a fume cupboard if they are not part of the current experiment.
• Ensure lightweight items such as tissues, disposable gloves and filter papers are not allowed to be drawn into the fan blades as they can degrade extract performance.
• When highly hazardous substances are being used e.g. cyanides, the fume cupboard should be appropriately labelled.
• Exercise extreme caution with ignition sources inside a fume cupboard. Ignition sources such as electrical connections, variac controllers and naked flames should only be used inside the cupboard if there are no operations involving flammable or explosive vapours. If possible, ignition sources should remain outside the fume cupboard.
• All electrical devices should be connected outside the fume cupboard to avoid electrical arcing that can ignite a flammable or reactive chemical.
• Avoid sources of high heat load within the fume cupboard as these will disturb the airflow pattern and reduce the overall efficiency of containment.
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• Clean all spillages promptly and all chemical residues from the fume cupboard enclosure after each use.
• Plan for possible emergencies. Fires in fume cupboards should be approached with extreme caution. The use of high pressure CO2 extinguishers can result in flames being blown into the duct work.
17.7.2 Microbiological Safety Cabinets Although in some ways microbiological safety cabinets (MSC) are similar in appearance to fume cupboards, they have very different uses. The department has many Class II MSCs that have an open aperture at the front through which the operator can carry out manipulations on potentially hazardous materials. They provide protection to both the operator and the materials being handled as the inward airflow is diverted beneath the work surface and is HEPA filtered before recirculation within the work area or before it is discharged into the building extract system. Air flow of a BioMAT model of Class II MSC air flow in re-circulatory mode and connected to a thimble is shown in figure 13. The downflow of HEPA-filtered air onto the work surface also minimises the possibility of cross-contamination within the cabinet.
HEPA filtered air MSCs must exhaust through a High Efficiency Particulate Air (HEPA) filter or equivalent, preferably direct to the outside air or, if this is not practicable, via the laboratory air extract system. The HEPA filter works by removing particulates (generally called aerosols) such as microorganisms, from the air. There is a requirement within BS EN 12469 that the minimum grading of filtration in MSCs is equivalent to H14 as defined within BS EN 1822, i.e. with a collection efficiency of 99.995% of 0.3 μm to 0.5 μm sized particles. The HEPA filter should ideally be part of the cabinet, but if not, they should be located as close to the cabinet exhaust as possible, to avoid accidental contamination of the building exhaust system with biological agents.
BioMAT model of Class II MSC air flow in re-circulatory mode
BioMAT model of Class II MSC air flow with filtered air vented via thimble to building ventilation
Figure 13: Air flow during normal safe operation
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17.7.3 Other Containment Devices
Airborne chemicals can also be contained or removed from the working area by other devices including:
• Glove box. Exhaust ventilated glove boxes vented to the outside through adsorption or High Efficiency Particulate Air (HEPA) filters, or a combination of the two, are used particularly for extremely toxic chemicals such as carcinogens. Access to the working chamber is through arm length rubber gloves mounted at the front of the box. Glove boxes can be made of rigid glass fibre or clear plastic or flexible PVC sheeting fitted over a rigid framework.
• Weighing station. Powder cabinets (also known as weighing stations, work stations or enclosures) utilize HEPA filtration technology and protect the operator from particles whilst weighing and handling powders. An example is shown in figure 14.
Bigneat F3-XI model of powder cabinet fitted with HEPA filter used in
re-circulatory mode
Figure 14: Powder weighing station
• Capture or canopy hoods. These are fitted over chromatographic, distillation or spectrophotometric or other heat generating equipment to contain emissions of hazardous chemicals and vent them safely to the outside.
• Down-draught ventilated benches fitted with perforated plates in the work surface to contain and remove dusts and dense vapours to the outside via adsorption and HEPA filters.
