The Environment and Human
Health
Chapter 20
I. Pollution and Human Health
A. Environmental Effects on Health
1. Pollution causes illness in two many ways.
a. Pollution may cause illness directly by
poisoning (lead poisoning)
b. Pollution may cause illnesses indirectly
(contaminated water)
2. The World Health Organization (WHO)
has been researching environmental
affects on human health.
3. People in developed
countries suffer less from
environmental causes of
poor health.
4. In developing countries
environmental causes of
poor health is largely due
to polluted water and
insect borne disease.
B.Toxicology is the study of the harmful effects of
substances on organisms.
1. We are exposed to small amounts of
chemicals every day in food, in the air we
breathe and some water we drink.
2. The amount of a harmful chemical to which a
person is exposed is called the dose.
3. The damage to health that results from
exposure to a given dose is called the
response.
4. A persistent chemical is a chemical that
breaks down slowly in the environmentexample DDT
5. The toxicity of a
chemical can be
expressed as a doseresponse curve.
6. Sometimes there is a
threshold dose.
C. Epidemiology is the study of the spread
of diseases.
1. A risk assessment is an estimate of the
risk posed by an action or substance.
2. Risk is the probability of a negative
outcome.
D. Pollution from Natural Sources
1. Some pollutants occur naturally in
nature.
2. Radon poisoning causes 15,000-22,000
cancer deaths a year in the US.
E. Pesticides
1. Chemicals designed to kill unwanted
organisms such as insects, fungi or
weeds.
2. Pesticides are designed to kill
organisms, they are often dangerous to
humans in large enough doses.
3. We are exposed to low levels of industrial
chemicals every ay, particularly inside new
buildings.
4. PCB’s have been used for years as
insulation in eletrical tranformers.
5. Children exposed to PCB’s can have
learning problems, and low IQ’s.
3. Widely used organophosphate pesticides
have replaced more persistent pesticides.
4. Organophosphates are very toxic, causing
nerve damage and perhaps cancer.
5. Such pesticides are dangerous to children
whose internal organs are still developing.
F. Waste Disposal
1. Most of our pollution is because of inadequate
waste disposal.
2. Many old landfills are leaking.
3. Sewage treatment plants release raw sewage
into a river or the ocean after heavy rains.
II. Biological Hazards
A. The environment’s Role in Disease
1. Infectious diseases are caused by
pathogens.
2. A host is an organisms in which a
pathogen lives all or part of its life.
B. Waterborne Disease
1. Nearly ¾ of infectious diseases are
transmitted through wqater.
2. Organisms that transmit the disease are
called vectors. (mosquitos)
3. The deadliest waterborne disease comes
from drinking water polluted by human
feces.
4. Cholera and dysentery.
5. Malaria was once the world’s leading
cause of death.
C. Environmetnal Change and Disease
1. We have polluted the environment and
by doing that we have made it more
suitable for pathogens to live and to
reproduce.
2. Example- hookworms has increased dur
to contaminated soil.
3. Over use of antibiotics have causes
resistance.
4. Some strains of Salmonella, E.Coli, and
TB are resistant to antibiotics.
5. Malaria on the march.
6. Emerging viruses.
7. Cross-specie transfers-bird flu.
THE END