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Health HazardsInstructional Goal

The participant will be able to interpret health hazard information for reducing personal risk when handling chemicals.

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What is a health hazard?What is a health hazard?

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Toxicology Toxicology isis

• the study of chemical toxicity

• based on epidemiological studies

• based on animal studies

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Factors Affecting Human Response Factors Affecting Human Response To Chemical ExposureTo Chemical Exposure

Toxic substances Route of exposure Chemical dose Individual sensitivity Interaction with other chemicals

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Forms of Toxic SubstancesForms of Toxic Substances

Solids Dusts Fumes Liquids Vapors Mists

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Health HazardsHealth Hazards

Asphyxiants Carcinogens Flammable Irritants

Sensitizers Mutagens Teratogens Target Organ

Poisons

You need to understand that some chemicals may fall into more than one category.

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Target Organ PoisonsTarget Organ Poisons

CNS Circulatory system Blood and blood forming system

(hematoxins) Liver (hepatotoxins) Kidneys (nephrotoxins) Reproductive Organs

Lungs Skin Eyes

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Routes of EntryRoutes of Entry

Inhalation

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Routes of EntryRoutes of Entry

Eye/skin (dermal contact)

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Routes of EntryRoutes of Entry

Ingestion

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Routes of EntryRoutes of Entry

Injection

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Acute ResponseAcute Response

•Headaches

•Dizziness

•Nausea

•Eye, skin or respiratory damage

•Unconsciousness

•Death

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Chronic ResponseChronic Response

Frequently not reversible

Liver, kidney, lung damage

Target organ poisons

Storage in fat (adipose) tissue

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Dose - Response RelationshipDose - Response Relationship

Dose of chemicalHow much / How long

Response of the biological system

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Dose Response CurveDose Response Curve

Dose

Res

po

nse

LD50

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Remember!!Remember!!

Toxic Dose(quantity vs time of exposure)

The smaller the number

the more toxic the dose!

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Toxicity isToxicity is

Rate of the potential for harm from a substance

Low toxicity vs. high toxicity

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Toxic ConcentrationToxic Concentration

Less than 1.0 mg/kg Dangerously Toxic

1- 50 mg/kg Highly Toxic

50 - 500 mg/kg Toxic

500 - 5,000 mg/kg Moderately Toxic

5 - 50 g/kg Low Toxic

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“All substances are poison .....

The right dose differentiates a poison and a remedy.”

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Substance InteractionSubstance Interaction

Additive 2 + 2 = 4 Synergistic 2 + 4 = 10 Potentiation 0 + 2 = 4 Antagonism 2 + 4 = 3

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Toxic dose is based upon normal distribution and average health.

Genetic variability is a major factor.

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Less Sensitive More Sensitive

Average Population

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PEL/TLV,IDLH arePEL/TLV,IDLH are

Exposure LimitsExposure Limits

airborne concentration of a material to which nearly all individuals may be repeatedly exposed without adverse health effects.

helps eliminate factor of genetic variability

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Common Units forCommon Units forExposure LimitsExposure Limits

ppm or ppb– used with liquid, vapor, and gas

mg/m3 (milligrams/cubic meter air)– used with solid particulates

suspended in air

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Exposure LimitsExposure Limits

Permissible Exposure Limit (PEL) Threshold Limit Value (TLV) Recommended Exposure Limit (REL) Time-weighted average (TWA) Short-term Exposure Limit (STEL) Ceiling (C) Immediately Dangerous to Life or Health (IDLH)

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Exposure LimitsExposure Limits

PELs - OSHA's enforceable standards

TLVs - intended for use in the practice of industrial

hygiene (ACGIH)

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Cautions and LimitationsCautions and LimitationsDon’t use PELs, REls, TLVsDon’t use PELs, REls, TLVs

as fine lines between safe and dangerous for evaluation or control of community air

pollution for estimating the toxic potential of

continuous exposure as proof of an existing disease or physical

condition

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Exposure Limits Exposure Limits

Time Weighted Average–8 hour day

–40 hour week

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TWA, STEL, CTWA, STEL, C

Time (hours)

Exp

osur

e (p

pm)

TWA

0 8

Measured Amount

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TWA, STEL, C

Time (hours)

Exp

osur

e (p

pm)

TWA

STEL

0 41 2 3

Maximum of 15 minutes

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TWA, STEL, C

Time (hours)

Exp

osur

e (p

pm)

TWA

STEL

0 41 2 3

C

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IDLH ValuesIDLH ValuesConcentrations of toxic substance from which escape is possible without irreversible harm should a worker's respiratory protective equipment fail.

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ToxicologyToxicology

Protection from ToxinsProtection from Toxins Know the potential for

toxicity of the materials with which you work.

Know the signs and symptoms of toxins effects.

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ToxicologyToxicology

Protection from ToxinsProtection from Toxins

Use engineering controls. Use common sense around

chemicals. Select and use protective equipment

based on MSDS and safety officer recommendations.

Wash exposed areas thoroughly before eating, drinking, or smoking.