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Appendix D - Training Program

Toxicology

Objectives/Samples of Behavior:

  1. Comprehend basic toxicological principles, terminology, and classification of materials.

  2. Explain the main routes of entry of substances into the body.

  3. Describe the modes of action substances may have on the body.

  4. Distinguish among carcinogens, mutagens, and teratogens.

  5. Distinguish between acute and chromic effects.

  6. Explain the relationship between exposure, dose, and response.

A.  Which poses greatest risk?

Chlorine

Ammonia

Toluene

Benzene

Hydrogen cyanide

Lead

Mercury

Asbestos

PCBs

B.  Risk Assessment for Chemicals

  1. What is the toxicity of the compound?

  2. What is the probability of exposure?

C.  Why Toxicology?

  1. Understand health & safety info

  2. Avoid fear & understand / appreciate need for:

  1. Fire protection

  2. Engineering and administrative controls for hazards

  3. Appropriate monitoring / accurate analysis

  4. Proper use / maintenance of PPE

  5. Proper handling of HW

D.  Toxicity

  1. Ability of a substance to produce injury once it reaches a susceptible site in the body

  2. Toxic vs. Hazardous

  1. Toxic:

What a substance is capable of as far as producing unwanted effects

A characteristic of a specific agent - can be used to compare to other agents

  1. Hazardous:

Degree of effects that can occur under various circumstances

  1. Toxicity classes:

Description

LD50 - mg/kg, Rats

LC50 - ppm, Rats

Extremely toxic

1 or less

10

Highly toxic

1-50

10-100

Moderately toxic

50-500

100-1000

Slightly toxic

500-5000

1000-10,000

Almost nontoxic

5000-15,000

10,000-100,000

Relatively harmless

over 15,000

over 100,000

E.  Toxicology

  1. Study of physical / chemical agents & the injury they cause to living organisms

  2. Modern:  "limits of safety"

"All things are poisons, for there is nothing without poisonous qualities.  It is only the dose which makes a thing poison."   Paracelsus

  1. Disciplines involved in toxicology:

Chemistry

Biochemistry

Physiology

Immunology

Physics & engineering

Statistics

Communication

F.  Classification

  1. Chemical:

Solid, liquid, gas

  1. Physical:

  1. Noise

  2. Radiation

  1. Biological

  1. Infectious agents

  2. Fomites

G.  Physical Forms

  1. Solids, liquids

  2. Gases - gaseous at room temp & pressure

  3. Vapors - product from normal liquid at room T & P

  4. Aerosols:

  1. Liquids - mists, fogs

  2. Solids - fumes, smokes, dusts, fibers

H.  Routes of Entry

  1. Inhalation #1

  2. Eye absorption

  3. Skin absorption (local vs. systematic)

  4. Ingestion

  5. Injection

I.  Modes of Action

  1. Irritants - inflammation

  2. Simple asphyxiants

  1. Nontoxic

  2. Displace O2

  1. Chemical asphyxiants

  1. Reduces body's ability to use O2

  2. Chemically active, need less dose for damage

  1. Anesthetics / CNS depressants - narcosis

  2. Systemic poisons - specific organs / systems

e.g. liver, kidneys, nerves, blood

J.  Additional Agents

  1. Lung-damaging agents - silica, asbestos

  2. Carcinogen - cancer

  3.  Mutagen - undesirable effects in descenants

  4. Teratogen - malformations of fetus

  5. Combinations

Toluene - nose irritation, CNS, liver/kidneys

Nitrogen mustard - skin irritation, cell necrosis, carcinogen

K.  Acute vs. Chronic

  1. Acute: single / multiple exposure over short time

  1. If rapidly absorbed - immediate response more likely

  2. Usually accidental exposures

  1. Chronic:  exposures over long times

  1. Onset of response - many years

  2. Occupational exposures

  3. Usually a measure of systemic effects (response)

L.  Dose-Response

  1. Exposure - e.g. breathing; being in a cloud of a certain number of parts per million (ppm) or milligrams per cubic meter (mg/m3) - LC50, LCt50

  2. Dose - what gets in / on

  1. LD50

  2. ED50

  3. mg/kg

  1. Response - death, specific disease developed

  2. For a chemical to produce toxic effects, the compound or metabolites must:

reach sensitive sites in body

in sufficient concentrations

for a sufficient length of time

M.  Mixtures & Dose-Response

  1. Additive - 1+1=2 - most common

Organic phosphatte insecticides

  1. Synergistic - 1+1=4

  2. Potentiation - 0+1=2

One - harmless chemical makes a 2nd worse than 2nd chemical alone

  1. Antagonistic - 1+1=0

2 chemicals producing opposite physiological effects

2 compounds react to form less toxic product

N.  Variables

Physiological Factors

Life Style Factors

Genetic makeup

Smoking

Age

Drug intake

Sex

Alcohol use

Disease state & previous exposure history

Job stress

Immunologic status

Physical condition
 

Diet / nutrition

 

Co-exposure - other chemicals

Factors for HW workers:

  1. Exposure to multiple compounds / mixtures

  2. Over-reliance or over-confidence on PPE

  3. Increased breathing rate

  4. Increased perspiration & elevated skin temp

  5. Potential for increased contact (breakthrough)

  6. Physical hazards of the environment (sharp edges on drums, etc.)

O.  Sources of Info

  1. People - BEEs, occupational physicians, poison control centers, AL/OE

  2. Texts/ databases - NIOSH, RTECS, TOMES +, SAX

  3. MSDS - material safety data sheets

  1. Substance's physical / chemical properties

  2. Health & fire hazards

  3. Type of PPE needed

  4. Recommended 1st aid for exposures

  5. Planning needed in case of spills, fires, etc.

  6. Any special precautions