1. Environmental Hazards & Human Health

3. Environmental Hazards
Complex interactions
Biosphere, atmosphere, hydrosphere, lithosphere
Industrialized Societies
Generate & dump huge amount of pollutants/toxic wastes
Agents
Biological, chemical, physical
Effects
Acute
Chronic

4. Damages Living Organism Degree of biological harm
Toxin
Inhaled, ingested, absorbed
Sufficient Dosage
Damages Living Organism
Degree of biological harm
How do we determine toxicity?

5. Environmental Toxicology
Study of effects of chemical, physical & biological agents
Help policymakers
Determine costs & benefits
What affect they have
Complicated
Many stressors in environment
System must evaluated for an extended period of time
Must be clear to evaluate

7. Toxicity Depends on Dose Exposure Who (adult vs. child)
How well does body’s detox work
Liver, kidneys, lungs
Genetics
Solubility
Fat vs. water

8. Bioaccumulation/Biomagnification
Persistence
Bioaccumulation/Biomagnification
Move through food web
Accumulate or increase concentration
Chemical Interactions
Synergy

9. Difficult, Costly & Controversial
Estimating toxicity levels & risks have serious limitations
Analysts work with available info which never seems sufficient
Only 10% of 85,000 synthetic chemicals are registered
Only 2% have be adequately tested
Teratogen, mutagen, carcinogen
Most chemicals are considered innocent until proven guilty

10. Pollutants Biological or infectious Chemical Bacterial, fungi, viruses
TB, malaria, AIDS
Chemical
Heavy metals (Hg, Pb, Cd, As, Cr)
Organic compounds
Food additives, pharmaceuticals
20 million synthetic chemicals
POP’s – persistent organic pollutants
PCB’s, dioxin, DDT, Aldrin, Dieldrin

11. Endocrine disruptors Radiation Thermal Particulates Asbestos EMF’s
DDT, Phthalates, PCB’s
Radiation
Thermal
Particulates
Dust, soot, asbestos fibers
Asbestos
EMF’s
Transmission wires
Noise
Cultural
Smoking, sunbathing, drug abuse, risky sexual behavior

12. Risk Assessment & Management
What is the hazard?
Probability of risk?
Consequence of risk?
Risk Assessment is
Process of evaluating the risk(s) associated with a hazard
Difficult, costly & controversial

14. Risk Assessment ID Hazard Dose-Response Exposure Testing
Statistical analysis
Dose-Response
Relationship between dose & health effect
Exposure
Intensity, duration & frequency

15. Risk Characterization
Delineate health risk
Potential of health problem
Evaluate testing results

16. Dose-Response Measure of Toxicity Dose Response
The amount that enters the body
Lethal doses vary depending on age, sex, health, metabolism, and genetic makeup
Response
The type & amount of damage that exposure to a particular dose causes

17. Testing Epidemiology Scientists perform animal tests
Study of populations & their exposure to certain chemicals and/or patterns of toxicity
Scientists perform animal tests
LD50 lethal dose to 50% of population
Mass of dose/Kg of body weight
The smaller the LD50 the greater the toxicity
TD50 threshold dose to 50% of population
Dose induces effects

18. Dose-Response Curve
Graph that relates amount of substance with the response
X-axis is amount or dose of substance
Y-axis is the response
Threshold Dose
Point on graph where response is first observed

21. Risk Management Deciding whether or how to reduce a risk
Thorough review of information
How does it compare with other risks
How should it be reduced
Reduction strategy
Cost

22. Who Makes Decision? Law makers & administrators Public
EPA, city, county
Public
Does weight of evidence justify a regulatory action
Cost benefit analysis
Risk benefit analysis
Public preference