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Risk, Toxicology and Human
Health: Chapters 10
EVSC 404:Enviromental Science II
Reading Assignment: Environmental
Science, Miller
Chapter 10: Pages 203-220
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Environmental Health
Health: State of complete physical, mental,and social well-being.
Disease: Deleterious change in bodyscondition in response to environmentalfactor.
Environmental Health: Focuses on the
external factors that cause disease, includingnatural, social, biological and chemicalagents
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Risks and Hazards
Risk: Possibility of suffering a hazard thatcan cause injury disease , economic loss, orenvironmental damage.
Common Risks
Cultural
Chemical
Physical
Biological
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Cultural Risk
Cultural Risks: These include unsafe
living, lifestyle, and working conditions,
Examples include- Smoking,
- Alcohol
- Poor diet
- Driving
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Physical Risk
Physical Risks: These result from ionizing
radiation, fires, drought, tornadoes, and
hurricanes, floods, etc. Earthquakes: caused by plates moving past
each other
Volcanoes: Result when molten magma isreleased. e.g. Mt. St. Helen (1980).
Killed 57 people
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Biological Risk
Biological Risks: These are caused by
diseases causing bacteria, viruses,
parasites etc
Types:
Transmissible Non-transmissible
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Biological Risk
Transmissible; Caused by living organismswhich are passed from one person toanother.
Infectious agents can be spread by air, waterfood, body fluids etc.
Non-human carriers-Vectors
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Biological Hazard
Worlds Most Deadly include:
Acute Respiratory Infections-about 4.3
killed annually Diarrheal diseases- about 3.2 M killed
Tuberculosis- about 3M killed
Malaria -about 2M
Hepatitis-B (1-2 M), AIDS(600,000)
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Biological Risks
Ecological Diseases: Diseases which affect
mostly wildlife , domestic animals and
plants. Chronic Wasting Disease (CWD)
CWD is spreading and killing deer and
elk in N. America It is caused by a protein calledprion
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Biological Risks
CWD is a member of a family of
irreversible, degenerative diseases known as
Transmissible Spongifrom Encephal-opathies (TSE).
TSE also include mad cow disease, scrapie
in sheep and Creutzfelt-Jacob disease inhumans
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Biological Risks
Sudden Oak Death Syndrome (SODS): A
diseases caused by a fungusPhytopthora
rumorum which is killing oak trees inCalifornia s an example of an ecological
disease affecting trees.
Black band Disease is another examplekilling corals- caused by algae (Phormidium
corallyticum).
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Chemical Hazard
Result from harmful chemicals in air, water,soil and food.
Types include
1. Hazardous Chemicals: These areclassified as chemicals which areflammable, acids, oxidizers, corrosiveetc.
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Chemical Hazard
2. Toxic Chemicals: Chemicals which are
fatal to over 50% of test animals at
given concentrations, e.g. Potassiumcyanide, chlorinated hydrocarbons,
toluene, xylene
Many are neurotoxins. Neurotoxins arespecial class of metabolic poisons that
attack nerve cells.
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Chemical Hazard
Types include most pesticides, heavy
metals, anesthetics
About 850 compounds recognized asneurotoxins.
3. Mutagens: Cause Mutation or damage
DNA in cells. Include certain chemicals,radiations
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Chemical Hazards
4. Teratogens. Causes birth defects e.g.alcohol, thalidomide.
5. Carcinogens: Cancer causing chemicals,e.g. some pesticides, nicotine.
6. Allergens: Substances that activate theimmune system, e.g. fomaldehyde
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Sources and Fate Of
Environmental Hazards
Sources:
1. Agriculture:Fertilizes, Pesticides
2. Industries: Organics, Heavy Metals
3. Construction: Sediments
4. Domestic Activities:Sewage, Solid
wastes
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Sources and Fate Of
Environmental Hazards
Fate of Environmental Hazards
1. Soil
2. Air
3. Water
4. Food
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Factors in Environmental Toxicity
1. Factors Related to toxic Agent
Chemical Nature
Solubility
Concentration
Persistence:
Degradable vs. Non-degradable
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Factors in Environmental Toxicity
2. Factors related to Exposure
Route of Exposure
3. Factors related to Organism
AgeSensitivity etc.
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Measuring Toxicity
Toxicology: Study of the adverse effects on healthcaused by chemicals.
Toxicity: Measure of how harmful a chemical is.
Dose: Amount of potentially harmful substancewhich is ingested , inhaled or absorbed.
Response: Amount resulting in damage or adversehealth effect
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Measuring Toxicity
Determining Effect of Toxic Chemicals.
1. Case Reports-usually made by
physicians. 2. Laboratory Investigations-usually uses
lab animals.
3. Epidemiology-Study of patterns ofdisease or toxicity to find out why
people got sick.
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Measuring Toxicity
Animal Testing
Dose/Response Relationships
- Paracelsus: The Dose makes the poison
LD50: Dose to which 50% of test
population is sensitive
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Measuring Toxicity
Toxicity ratings: Group chemicals based on
their relative toxicity
Acute Exposure- Single dose
Acute Effect: Immediate or rapidreaction to and exposure
Chronic Exposure: Over entire lifetime
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Measuring Toxicity
Subchronic: Repeated exposure for somefraction of a lifetime.
Chronic Effect: Long-lastingConsequence
Detection Limits
Standards
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RISK ANALYSIS
Risk analysis: Identifying hazards and
evaluating their associated risks.
Risk Assessment: Evaluating risksassociated with hazards
Risk management: Making decisions
about reducing or eliminating risks
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RISK Assessment
1. Determining Type of risk
2. Estimating probability of risk
3. Estimating level or frequency of exposure
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Environmental LAWS
1. OSHA: Occupational Safety and
Health Act
2. FIFRA: Federal InsecticideFungicide and Rodenticide Act
3. FFDCA; Federal Food Drug and
Cosmetic Act
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Environmental LAWS
3. CWA: Clean Water Act
4. CAA: Clean Air Act
5. RCRA: Resource Conservation andRecovery Act.
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