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Environmental Health
The Rise and Fall—and
Rise?—of DDT
• DDT is the least expensive way of killing the mosquitoes
that cause malaria.
• DDT harms fish and birds, and can cause liver damage,
cancer, and convulsions in humans.
• In the 1970s many countries banned the use of DDT, but
some African countries have resumed its use to control
Talk About It Evidence shows that DDT damages
ecosystems but helps eradicate malaria in areas
where millions of people die of the disease each
year. Should DDT be used in malaria-stricken areas?
Why or why not?
Lesson 9.1 An Overview of Environmental Health
One third of death and disease in the least
developed nations is a direct result of
environmental causes.
Lesson 9.1 An Overview of Environmental Health
Types of Environmental
Health Hazards
• Biological: Viruses, bacteria, and
other organisms that cause
• Social: Lifestyle choices that
endanger health
• Chemical: Harmful artificial and
natural chemicals in the
• Physical: Natural disasters and
ongoing natural phenomena, such
as UV radiation, that can cause
health problems
Lesson 9.1 An Overview of Environmental Health
• The study of disease in human
populations—how and where
they occur and how they can
be controlled
• Often involves studying large
groups over long periods
• Can determine statistical
associations between health
hazards and effects, but can’t
prove the hazards actually
caused the effects
Lesson 9.1 An Overview of Environmental Health
• The study of how poisonous
substances affect an organism’s
• Toxicity is a measure of how
harmful a substance is.
• Toxicologists look at toxicity by
determining dose-response
Lesson 9.1 An Overview of Environmental Health
Individual Responses
• Sensitivity to hazards varies
with age, sex, weight, and
immune system health.
• Many diseases have
genetic as well as
environmental factors.
Did You Know? Thalidomide, a drug that
currently shows promise for treatment of
Alzheimer's, AIDS, and some cancers,
caused thousands of severe birth defects
when it was used as an anti-nauseal in
the 1950s and 60s.
Lesson 9.1 An Overview of Environmental Health
Risk Assessment
• Risk: The probability that a
hazard will cause harm
• Risk assessment: The
process of measuring risk
• Takes into account:
• The type of hazard
• How frequently humans will
be exposed to it
• How sensitive people are to it