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 malaria.
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.
Types of Environmental Health Hazards
• Biological: Viruses, bacteria,& other orgs that cause disease
• Social: Lifestyle choices that endanger health
• Chemical: Harmful artificial & natural chems in env’t
• Physical: Natural disasters & others as UV radiation, that can cause health problems
Lesson 9.1 An Overview of Environmental Health
Epidemiology
• Study of disease in human
pops—how & where they
occur & how they can be
controlled
• Involves studying large grps
over long periods
• Can determine statistical
associations betwn health
hazards & effects, but can’t
prove the hazards actually
caused effects
Lesson 9.1 An Overview of Environmental Health
Toxicology
• Study of how poisonous subs
affect an org’s health
• Toxicity: measure of how
harmful a sub is.
• Toxicologists look at toxicity
by determining dose-
response relationships.
Lesson 9.1 An Overview of Environmental Health
Individual Responses
• Sensitivity to hazards varies
with age, sex, weight, &
immune system health.
•Many diseases have
genetic as well as env’tal
factors.
Lesson 9.1 An Overview of Environmental Health
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.
Risk Assessment
• Risk: probability that a
hazard will cause harm
• Risk assessment: The
process of measuring risk
• Takes into account:
• Type of hazard
• How frequently humans will be exposed to it
• How sensitive people are to it
Lesson 9.1 An Overview of Environmental Health
Lesson 9.2 Biological and Social Hazards
Three quarters of infectious disease deaths are caused by five types of diseases: respiratory infections, AIDS, diarrheal diseases, tuberculosis, and malaria.
Tuberculosis-causing
bacteria
Infectious Diseases
Lesson 9.2 Biological and Social Hazards
Did You Know? In 2002, AIDS killed about 2 million people worldwide— almost equal to the entire population of Arkansas.
• Caused by pathogens
• Spread by human & animal
contact & thru contaminated
food & water
• Cause of almost half of all deaths
in developing nations
• Prevention of
spread of infectious disease:
Cover mouth when cough, wash
hands often, & stay home from
school if sick
Emerging Diseases
•Diseases appearing human pop for the 1st time or suddenly
beginning to spread rapidly
•Humans have little/no resistance & no vaccines have been
dev.
• Facilitated by
increasing human
mobility, growing
antibiotic
resistance, &
env’tal
changes
Lesson 9.2 Biological and Social Hazards
Responding to Emerging Diseases
•World Health Organization (WHO):
Monitors health events worldwide &
coordinates international responses to
emerging diseases
•Centers for Disease Control and
Prevention (CDC): Responds to
emerging diseases in the United States;
CDC dev pandemic plans to deal w/
spread of H1N1 flu virus.
Lesson 9.2 Biological and Social Hazards
H1N1 Virus
Social Hazards
Lesson 9.2 Biological and Social Hazards
• Some easier to avoid than
others
• Ex: smoking, being exposed
to secondhand smoke, living
near an old toxic waste site,
working w/ harmful
chemicals & eating fatty
foods
Lesson 9.3 Toxic Substances in the Environment
Chemicals are all around us, and all of them can be harmful to our health in large enough amounts. In other words, “The dose makes the poison.”
Chemical Hazards
• Any chemical harmful in large enough amts
• Pollutant: released into envt--some harmful impact on
people & org
•Chemical hazards: not necessarily pollutants & pollutants
are not necessarily chemical hazards.
Lesson 9.3 Toxic Substances in the Environment
Oil Pollution
Types of Chemical Hazards
•Carcinogens: Cancer-causing chemicals
•Chemical mutagens: Chemicals cause genetic mutations
• Teratogens: Chemicals harm embryos & fetuses
•Neurotoxins: Chemicals that affect nervous system
• Endocrine disruptors: Chemicals that interfere w/ the endocrine system
•Allergens: Chemicals that over-activate the immune system
Lesson 9.3 Toxic Substances in the Environment
Dust mite protein is a common
allergen.
Sources of Outdoor Chemical Hazards
• In the air: Natural sources-
volcanic eruptions human
sources-pesticides
• In the ground: Pesticide
use, improper disposal of
electronics, etc.
• In the water: Chem runoff
from land or direct drainage
of toxic subs into water
Lesson 9.3 Toxic Substances in the Environment
A leaking oil line
Bioaccumulation and Biomagnification
•Bioaccumulation: buildup of toxic
substances in the bodies of orgs
•Biomagnification: increased conc
of toxic substances w/ each step in
food chain
• Persistent organic pollutants are
biomagnified & stay in the env’t for
long periods of time & over long
distances.
Lesson 9.3 Toxic Substances in the Environment
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