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TOXICOLOGY – The study of poisons
Materia Medica – poisons classification- DioscoridesCourt of Nero, 50 AD
“The dose makes the poison”- Paracelsus16th century German
physician
Scope of the Problem Reagents can represent a toxicity
hazard to students and instructor. Protection of students and staff is
important. Most common sources of contamination
Pipetting by mouth Eating with contaminated hands Drinking from contaminated containers Applying contaminated make-up
EFFECTS OF TOXIC CHEMICALS
Structural Differences are very important:
For example, two closely related PCB’s
Basic Considerations Dose
Length of Exposure
Organs or systems on which the chemicals have an effect
Hypersensitive
Normal
Normal
Hyposensitive
Dose-Response Relationships
Dose Response Relationship Dose make the poison Dose units provide toxicity
measurements Major response terms for toxic or
lethal: Toxic concentration: TC Toxic dosage: TD Lethal concentration: LC Lethal dosage: LD
Toxicity may be different in different species:
Most Common Routes of Entry
Oral Gastrointestinal tract exposure
Inhalation Respiratory tract exposure
Pericutaneous Through the skin, a dermal or
epidermal exposure
Major Sites of Exposure, Metabolism, Storage and Excretion
Local and Systemic Effects Local Effect
Occurs directly where the chemical contacts the body
Systemic Effect Caused when a toxic reagent is absorbed
and circulated by the blood to systems and organs that can be effected by the toxin
Effects may be lessened by the body’s ability to detoxify and eliminate the toxin
Acute and Chronic Effects
A. Acute exposure Single or short-term exposure May have sudden onset of affect and a
short duration Some short term exposure may cause:
Permanent adverse effects Delayed effects Chronic effects
Acute and Chronic Effects Continued
B. Chronic exposure and effects Repeated or prolonged exposure to
low concentrations of toxic chemicals Chronic effects are:
Of long duration Frequently recurring Slowly progressing in seriousness
c. Similar exposure to some toxins will have effects that stop when exposure stops
General Classes of EffectsA. Immune suppression
t-cells t-cells
B. Central nervous system effect CNS is most sensitive to adverse changes in brain
function or nerve conditions Drugs: designer drugs, phenobarbitol, narcotics
Solvents: toluene, styrene, xylene, methyl ethyl ketone
General Classes of EffectsContinued
C. Carcinogenic Uncontrolled growth of genetically-
controlled cells Multi-stage theory
Initiation Promotion Progression
D. Tetratogenesis – changes in embryos
Effects on Life ProcessesA. Exposure of an individual to a toxic
substance may alter one or more basic life processes, including:
1. Irritability – ability to respond to stimulus2. Conductivity – nerve impulses3. Contractility – ability to change form by
shortening4. Metabolism5. Integration – ability to coordinate activities by
acceleration or deceleration or activities6. Adaptation7. Reproduction – ability to repair and reproduce
Effects on Life ProcessesContinued
B. System toxic effects are often first recognized as shift in physiological or behavioral patterns
Shift may be subtle or dramatic
Toxicology Management
A. Risk vs. Benefit Least-toxic reagents Alternate procedures Simulations
B. Voluntary vs. Involuntary Risk Instructor Student Experienced research scientist
Toxicology ManagementContinued
C. Setting Standards OSHA
Chemical hygiene plan “Right to Know” law Disposal regulations
NIOSH
D. Sensitive Sub-Populations Pregnant females Allergic reactors
Toxicology Databases Toxnet – National Library of Medicine
http://toxnet.nlm.nih.gov/Databases on toxicology, hazardous chemicals, environmental health, and toxic releases
Toxicology tutorial
Amer. Assn. of Poison Control Centershttp://www.aapcc.org/
OSU Community Outreach and Education ProgramClassroom activities and labs - toxicology
http://www.hydroville.org