1. Environmental Health, Pollution and Toxicology
Chapter 15
Environmental Health, Pollution and Toxicology

2. Terminology
Pollution: introduces harmful materials or produces harmful conditions to the environment
- introduced through a) Point Sources:
b) Area Sources:
c) Mobile Sources:
Contamination: making something unfit for a particular use through the introduction of undesirable material
Toxicology: the science that studies chemicals known to be toxic
Carcinogen: a type of toxin that increases the risk of cancer
Synergism: the interaction of different substances resulting in a total effect greater than the sum of the effects of the separate sources

3. Measuring Pollutants Measuring depends on the substance Common Units
ppm: Parts per million
ppb: Parts per billion
Micrograms per cubicle meter (measures air)

4. Categories of Pollutants
Infectious Agents
Toxic Heavy Metals
Organic Compounds
Radiation
Thermal Pollution
Particulates
Asbestos
Electromagnetic Fields
Noise Pollution
Voluntary Exposure

5. Infectious Agents
Spread from the interactions between individuals and food, water, air, or soil
Greatest mortality in developing countries
Examples:
Legionnaires' disease
Giardiasis
Salmonella
Malaria

6. Toxic Heavy Metals Mercury, lead, cadmium, nickel, arsenic...
Travel through toxic pathways
Biomagnification: the accumulation or increase in concentration of a substance in living tissue as it moves through a food web.
“Body burden”: accumulation of heavy metals in the body

9. Mercury and Minamata, Japan
Vinyl chloride factory
Mercury released in waste (inorganic)
Bacteria converted to organic compound
absorbed faster and retained longer (fish)

10. Mercury and Minamata, Japan
Illustrates four major factors that must be considered in evaluating and treating toxic environmental problems:
individual responses
pollutant may have a threshold
effects may be reversible
ecological and biological processes can alter pollutant

11. Organic Compounds Organic Compounds: composed of carbon
Synthetic Organic Compounds: used in industrial processes
Persistent Organic Pollutants: Synthetic organic compounds often containing chlorine, that do not easily break down in the environment.
Hormonally Active Agents: Chemicals in the environment able to cause reproductive and developmental abnormalities in animals

12. Thermal Pollution
Heat released into water or air that produces undesirable effects
Sudden to long-term
Natural and human induced (electric power plants – major source)
Impacts: DO concentrations, spawning; disease susceptibility; physical stress
Cooling towers, artificial lagoons

14. Particulates Dust, soot, asbestos fibers Natural
dust storms; fires; volcanic eruptions
Human activities
farming; oil and coal combustion

15. Asbestos
Term for several minerals that take the form of small, elongated particles or fibers
Industrial use
fire prevention; insulation

16. Electromagnetic Fields (EMF)
Electric motors, transmission lines; appliances
Fields drop off quickly with distance
Some indication that MF may cause problems

17. Noise Pollution increases exponentially as a power of 10
Unwanted sound
Travels as waves
Logarithmic
increases exponentially as a power of 10
Pitch, frequency and length determine environmental effects

18. Voluntary Exposure Tobacco, alcohol and drugs
Various results, but end result is the degradation of mind and body

19. General Effects of Pollutants on Wildlife Populations - Changes in Abundance - Changes in Distribution - Changes in Birth Rates - Changes in Death Rates - Changes in Growth Rates

22. Concept of Dose and Response
The effect of a certain chemical on an individual depends on the dose (dose response)
Individuals differ in their response to chemicals
Dose-Response Curve:
- LD-50 (Lethal)
- ED-50 (Effective)
- TD-50 (Toxic)
Threshold Effects:
- the level below which effects are not observable and above which effects become apparent

27. Ecological Gradients
Changes in vegetation with distance from a toxic source
Tolerance: The ability to resist or withstand stress resulting from exposure to a pollutant or harmful condition
- Behavior vs. Physiological
- Genetic
Acute and Chronic Effects

28. Risk Assessment Four steps: 1. Identification of the hazard
Investigate the population; test on animals; study at molecular level on cells
2. Dose-Response assessment
Relationship between dose and effect
3. Exposure assessment
Evaluate the intensity, duration and frequency of human exposure
4. Risk characterization
Rank risks in terms of magnitude of the potential environmental health problem that might result from exposure

29. Precautionary Principle
The idea that in spite of the fact that full scientific certainty is often not available to prove cause and effect, we should still take cost-effective precautions to solve environmental problems where there exists a threat of potentially serious and/ or irreversible environmental damage