EVSC 404.Env Healthand Toxicol.fa05

7/30/2019 EVSC 404.Env Healthand Toxicol.fa05

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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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EVSC 404.Env Healthand Toxicol.fa05

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