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Chapter 15
Environmental Health,
Pollution and Toxicology
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 desirable material
Toxicology: the science that studies chemicals that should 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
Measuring Pollutants
• Measuring depends on the substance
• Common Units
– ppm: Parts per million
– ppb: Parts per billion
– Micrograms per cubicle meter (measures air)
Categories of Pollutants
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Infectious Agents
Toxic Heavy Metals Organic Compounds
Radiation
Thermal Pollution
Particulates
Asbestos
Electromagnetic Fields
Noise Pollution
Voluntary Exposure
Toxic Heavy Metals
• Travel through toxic pathways
• Biomagnifications: the accumulation or
increase in concentration of a substance in
living tissue as it moves through a food
web.
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
General Effects of Pollutants
- Changes in Abundance
- Changes in Distribution
- Changes in Birth Rates
- Changes in Death Rates
- Changes in Growth Rates
Concept of Dose and Response
• The effect of a certain chemical on an individual
depends on the does
• Individuals differ in their response to chemicals
Dose-Response Curve:
- LD-50
- ED-50
- TD-50
Threshold Effects:
- the level below which effects are not observable
and above which effects become apparent
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
Acute and Chronic Effects
Risk Assessment
• 4 steps
1. Identification of the hazard
2. Dose-Response assessment
3. Exposure assessment
4. Risk characterization
Precautionary Principle
• The idea that in spit 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