Subpart Z29 CFR 1910

IH ToxicologyIH Toxicology

Industrial HygieneIndustrial Hygiene

• Anticipation

• Recognition

• Evaluation

• Control

–of environmental factors that can cause sickness or disease

Hygienist ActivitiesHygienist Activities

• On which function does an IH* spend the most time? *industrial hygienist

• Evaluation

• Which most Difficult?

• Anticipation

• Which should spend most time?

• Control

Control MethodsControl Methods

Control at the SourceControl at the Source

• Chemical substitution

• Redesign the process

• Isolate the process

• Enclose the process

• Mechanize

Control of the PathControl of the Path

• Local exhaust ventilation

• General ventilation

• Housekeeping

• Work methods (wetting down, etc.)

Control at the WorkerControl at the Worker

• Respirators and other PPE

• Administrative controls

• Enclose the worker

• Hygiene facilities and practices

Hierarchy of ControlHierarchy of Control

• Control the source

• Control the path

• Control the exposure at the worker

Hierarchy of ControlHierarchy of Control

• Engineering

• Administration

• Personal protective equipment (PPE)

Types of Illnesses - TimeTypes of Illnesses - Time

• Acute - a disease that develops quickly after exposure

• Chronic - a disease that develops long after exposure

• Latency Period - the time between the first exposure and the development of disease

Routes of ExposureRoutes of Exposure

• Breathe the chemical – inhalation

• Swallow the chemical – ingestion

• Absorb through skin - skin absorption

In all cases, chemicals can travel through the body.

Important Body OrgansImportant Body Organs

Lungs Kidney

Blood Forming Reproductive

Nervous System Liver

–brain

–nerves

Forms of ChemicalsForms of Chemicals

Particles

–Dust - formed by Grinding /breaking - large particles

–Smoke - formed by burning - large particles

–Fume - formed by heating - small particles

Forms of ChemicalsForms of Chemicals

Gasses

–Gas - at room temperature–Vapor - heat to turn to gas ---

–Droplets - agitating a liquid

What is Dose?What is Dose?

Concentration & Time

Chemical InteractionChemical Interaction

• Additive Effects 2 + 2 = 4

• Synergistic Effects 2 + 3 = 9

• Potentiation Effects 2 + 0 = 8

• Antagonistic Effects 4 + 6 = 5

Signs of ExposureSigns of Exposure

• Dust, Mist, Smoke in the air

• Accumulation of dust or oils

• Unusual Smells

• Unusual Tastes

• Burning in the eyes

• Nose throat irritation

• Feel better during vacation

Contributory Factors to Contributory Factors to ToxicityToxicity

• Dose

• Absorption

• Rate of Transformation

• Excretion Rate

• Human Factors

• Route of Entry

Measuring ParticlesMeasuring Particles

• Concentration

• Weight of substance in volume of air

• Weight in milligrams - mg

• Volume in cubic meters m3

• mg/m3 = milligrams per cubic meter

Measuring Gasses or VaporsMeasuring Gasses or Vapors

• Volume concentration of gas in air

• Parts per million– Parts of gas in million parts of air– Cups in a million cups– Quarts in a million quarts– Similar to per cent, which is actually parts per

hundred

OSHA PEL’sOSHA PEL’s

PEL = Permissible Exposure Limit

The concentration of a chemical a worker can be exposed to . . .

–8 hours per day

–working lifetime

without experiencing health problems

Kinds of PEL’sKinds of PEL’s

• TWA = Time Weighted Average

• Levels vary over a day

• OK for chemicals causing chronic disease

TWA Example #1TWA Example #1

0

2

4

6

8

10

12

14

8:00AM

9:00AM

10:00AM

11:00AM

12:00PM

1:00PM

2:00PM

3:00PM

4:00PM

Time

Ex

po

su

re in

PP

M

TTWA Napthalene

TWA Example #2TWA Example #2

0

2

4

6

8

10

12

14

16

18

8:00AM

9:00AM

10:00AM

11:00AM

12:00PM

1:00PM

2:00PM

3:00PM

4:00PM

Time

Ex

po

su

re in

PP

M

TWA for Nephthalene

CeilingCeiling

0

10

20

30

40

50

60

Time

Ex

po

su

re

TWA PPM for Benzene

Acceptable Max

Ceiling PELCeiling PEL• Concentrations can never exceed

• Indicated by OSHA as “C”

• Appropriate for chemicals causing acute disease

• If can’t measure instantaneously, take 15 minute (worst case) sample

STELSTEL

-3-113579

11131517192123252729313335

8:00AM

10:00AM

12:00PM

2:00PM

4:00PM

Time

Ex

po

su

re

15 minute STEL

30 ppm IDLH

STELSTEL

STEL = Short term exposure limit

• Period of time shown in standard where PEL can be exceeded

• Still an absolute maximum that can not be exceeded (a ceiling)

• Must still meet the TWA

Skin NotationSkin Notation

• If OSHA says “skin,” then can’t have any skin contact

• Appropriate where there is [a possibility of] skin absorption

How Do We Get These PEL’s?How Do We Get These PEL’s?

• Concensus standards ACGIH, 1968

• ANSI

• New standards attempted to upgrade not successful

Other Sources of StandardsOther Sources of Standards

• ACGIH - TLV’s

• NIOSH - REL’s

• Company standards

Table Z-1Table Z-1

• Based on 1968 ACGIH

• Lists chemical name

• CAS (identifying) number

• PEL (Time Weighted Average)

• Skin (if applies)

• Ceiling (if applies)

• As stated in a previous memorandum dated November 8, 1996:

• Compliance officers can choose one of two approaches for employees who work extended work shifts beyond 8-hours. The choice taken will depend on the nature of the hazardous chemical.

11/10/1999 - OSHA policy 11/10/1999 - OSHA policy regarding PEL adjustments for regarding PEL adjustments for

extend work shiftsextend work shifts

• The first approach is to sample what the

compliance officer believes to be the

worst continuous 8-hour work period of

the entire extended work shift.

PEL AdjustmentsPEL Adjustments

PEL AdjustmentsPEL Adjustments

• The second approach is to collect multiple samples

over the entire work shift. Sampling is done such that

multiple personal samples are collected during the

first 8-hour work period and additional samples are

collected for the extended work shift. Unless a

compliance officer is dealing with lead, the PEL in

this approach is calculated based upon the worst 8-

hours of exposure during the entire work shift.

Table Z-2Table Z-2• Based on ANSI standards• Lists chemical name• CAS number• TWA• Acceptable ceiling• Peak• Duration

• "Acceptable ceiling concentrations." An employee's exposure to a substance listed in Table Z-2 shall not exceed at any time during an 8-hour shift the ceiling concentration limit given for the substance except for: – A time period, and up to a concentration not

exceeding the maximum duration and concentration allowed in the column under "acceptable maximum peak above the acceptable ceiling concentration for an 8-hour shift"

1910.1000(b) - Table Z-21910.1000(b) - Table Z-2

• The substances listed can have limits expressed as: – 8-hour TWAs– Ceilings– Peaks

• If a substance has both ceiling and peak limits, the peak is the level never to be exceeded

• Employee exposure level exceeding the ceiling but under the peak are required to comply with the margin notes provided in the table

Peak

1910.1000(b) - Table Z-21910.1000(b) - Table Z-2

• Example: – During 8-hour work shift, an employee may be

exposed to Substance A (with a 10 ppm TWA, 25 ppm ceiling, and 50 ppm peak) above 25 ppm (but never above 50 ppm) only for a maximum period of 10 minutes.

– Such exposure must be compensated by exposures to concentrations less than 10 ppm so that the cumulative exposure for the entire 8-hour work shift does not exceed a weighted average of 10 ppm.

1910.1000(b) - Table Z-21910.1000(b) - Table Z-2

Table Z-3Table Z-3• Mineral Dusts

– silica and silicates

– graphite

– coal dust

– Inert or nuisance dusts

(particulates not otherwise classified)

• Respirable: < 10 microns

– separated with cyclone

Substance Specific StandardsSubstance Specific Standards

31 specific chemicals–asbestos–benzene–coal tar pitch volatiles–lead–formaldehyde–arsenic

Substance Specific Substance Specific RequirementsRequirements

• Air monitoring• Control of exposure• Work practices• Respiratory protection• Medical surveillance

–medical removal (lead)• Record keeping• Worker training

Air Monitoring: Air Monitoring: Who, What, Where?Who, What, Where?

• Worst case sampling

• Representative sampling

• Personal vs. area sampling

• What conditions can affect sampling results?

Chemical PropertiesChemical Properties

• Flashpoint

• Vapor Density

• Vapor Pressure

• Specific Gravity

• Evaporation Rate

Air MonitoringAir Monitoring

• Pump

• Tube

• Collection device

• Direct reading

Air MonitoringAir Monitoring

• Calibrate pump with collection device before and after each sample

• Sample minimum of one hour less than full shift (for OSHA compliance)

Napthalene ExposuresNapthalene Exposures

15 ppm for 6 hours

5 ppm for 2 hours

Compute TWACompute TWA 15 ppm x 6 hours = 90 ppm hrs

5 ppm x 2 hour = 10 ppm hrs

8 hours 100 ppm hrs

____________________________

100 ppm hrs ÷ 8 hours = 13.8 ppm

Less Than Full Shift Sample?Less Than Full Shift Sample?

15 ppm x 7 hours = 105 ppm hrs

? ppm x 1 hour = ??? ppm

Confidence LimitsConfidence Limits

• C / PEL = Y

• LCL = y - SAE

• UCL = y + SAE

Confidence LimitsConfidence Limits

• LEAD

• 54 / 50 = 1.08

• 1.08 - .12 = .96

• 1.08 + .12 = 1.2

Beware the PELBeware the PEL

• If above the PEL are you definitely getting sick?

• If you’re below the PEL are you definitely safe?

• Why or why not?

Thank YouThank You..

Any Questions?Any Questions?