Pollutants are emitted from natural and
Species have evolved tolerances in
response to pollutants, however, when
a species with a low tolerance
encounters elevated concentrations of
pollutants their population drops or
even dies away.
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
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
depends on the substance
– ppm: Parts per million
– ppb: Parts per billion
– Micrograms per cubicle meter (measures
Categories of Pollutants
Toxic Heavy Metals Organic Compounds
BUTTERFLY MODEL for an Ecosystem Context.
Air, Water Workplace
Soil, Microbes Health Care
Plants, Animals Neighborhoods
Environment Biological and Environment
Features Filters Features
Air Quality Early Childhood
Food Quality Development
Water Quality Social Support
Organism Response to Pollution
Reactions are highly variable.
Differences due to body size, age,
general health, immune response,
previous exposures, sensitivity or other
Chemical A and B
Responses to Pollution
Some responses to exposure are
reversible, some are not.
Pollutants may undergo changes
through the actions of ecological or
biological processes…they may become
more toxic or less toxic.
Some pollutants may act synergistically.
Infectious diseases transmitted through
the air, water and soil are a serious risk
to humans and animals.
Diseases due to poor sanitation are the
greatest cause of death in developing
Toxic Heavy Metals
Naturally occurring metallic elements:
Toxic Heavy Metals
Do not degrade in the environment.
Persistent in biological tissue.
Actions found in CNS and tissues.
– Especially dangerous to children and
Can be biomagnified in food chains.
Organic Compounds: composed of carbon
Synthetic Organic Compounds: used in
Persistent Organic Pollutants: Synthetic
organic compounds often containing chlorine,
that do not easily break down in the
Hormonally Active Agents: Chemicals in the
environment able to cause reproductive and
developmental abnormalities in animals
Common Organic Pollutants
Synthetic organic solvents.
Dioxin (Times Beach, MO).
Synthetic organic compounds.
Common radiation sources:
– Ionizing radiation:
– Non-ionizing radiation:
The abnormal heating or cooling of
Affects on ecosystems readily observed.
Dissolved oxygen content can be changed
(increase in temp., decreased dissolved
Disruption of spawning cycles;
Whatmay cause this change in water
Particulates: small particles of dust, smog,
aerosols or mists.
May originate from natural or anthropogenic
sources: mobile or nonmobile.
Most particulates are not toxic but can
contaminate the lungs and cause pulmonary
or cardiovascular health problems.
Particulates can interfere with photosynthesis
and lung function in animals.
Volatile organic compounds;
Criteria vs. Noncriteria Pollutants;
Attainment vs. Non-Attainment Areas.
Noise: Unwanted sound.
Sound waves measured by intensity of
waves using sound level meters (dBs on
the A, B or C scale).
Noise exposures may lead to stress-
Permanent or temporary (shifts)
Acute vs. Chronic Effects
Acute effects: Begin immediately or
soon after exposure occurs.
Exposure usually exceeds safe
Effects may be reversible.
Chronic effects: Exposure to low level
concentrations over a long period of
Effects may not be reversible.
Dose-Response and Ecological
Organisms that are generally located
nearest to the pollutant source show the
most severe and acute effects of
Tolerance of organisms vary along
Tolerance of organisms is an indication
of the ability of an organism to resist or
Tolerance to Exposure
Tolerance is dependent on:
Behavior (avoidance mechanisms);
Physiology and detoxification;
Four basic steps:
– Hazard identification;
– Toxicity assessment;
– Exposure assessment;
– Risk characterization.
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