Download Pollution and Human Health

POLLUTION AND
HUMAN HEALTH
ENVIRONMENTAL SCIENCE UNIT 7
ENVIRONMENTAL EFFECTS ON
HEALTH
• Pollution can cause illness in two ways
• Directly by poisoning
• Lead poisoning
• Lung cancer
• Indirectly by infectious diseases that are spread in polluted
environments
• Cholera
• River blindness
• People in developed countries suffer less from
environmental causes of poor health
• In developing countries, environmental causes of poor
health are largely due to parasites and bacteria in
polluted water and insect-borne diseases
• Malaria
TOXICOLOGY
• Toxicology – study of toxic substances including their
nature, effects, detection, methods of treatment, and
exposure control
• Toxicologists determine the following:
• Whether the concentration of any particular chemical in the
environment is high enough to be harmful
• How much of the pollutant is in the environment and how
much gets into the body
• What concentration of the toxin damages the body
• Individual’s response depends on:
• Number of times a person is exposed
• Person’s size
• How well the person’s body breaks down the chemical
• Dose-response curve shows relative effect of various
doses of a drug/chemical on one or more
organisms
• Threshold dose
• Exposure < threshold dose has no adverse effect
• Exposure > threshold dose usually leads to adverse effects
EPIDEMIOLOGY
• Epidemiology – study of the spread of diseases
• Epidemiologists collect data from health workers on
when and where cases of a disease have occurred
• Health officials determine risk posed by specific
hazards
• Risk assessment – estimate of the risk posed by a
specific substance
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Compile and evaluate existing info
Determine how people might be exposed
Determine toxicity of the substance
Characterize the risk that the substance poses to public
• Risk assessments may lead to EPA regulations
POLLUTION FROM NATURAL SOURCES
• Some pollutants occur naturally
• Radon gas (radioactive) may seep into buildings
from granite
• Causes estimated 15,000 – 22,000 cancer deaths each year
in U.S.
• Particulates such as dust, soot, etc. are most
common natural pollutants
• Particulates become trapped in air sacs in lungs, causing
irritation that can worsen lung conditions such as chronic
bronchitis and emphysema
• Dust storms, volcanoes, wildfires
• Heavy metals
• Dangerous heavy metals include arsenic, cadmium, lead,
mercury
• Cause nerve damage
• High levels of selenium can cause birth defects
POLLUTION FROM HUMAN ACTIVITIES
• Only 10% of commercial chemicals have been
tested for toxicity
• About 1,000 new chemicals introduced every year
• Quality of life in U.S. is better than most other places
b/c most vehicles and factories have pollution
control devices
• New health risks are discovered frequently
• Example: Scientists now believe that chemical pollution
may be at least part of the cause of Parkinson’s disease
and Alzheimer’s disease
• Burning fuels introduces enormous amounts of
pollutants into the air
• CO, particulates
• Contributes to many premature deaths from asthma, heart
disease, etc.
• Long-term exposure to soot particles raises a person’s risk of
dying from lung and heart diseases
• Pesticides allow more food production but are
often dangerous to humans in large doses
• Most modern pesticides are organophosphates and break
down quickly in the environment
• Toxic, especially to children
CHEMICALS THAT DISRUPT
HORMONES
• Ecotoxicology – study of effects of pollutants on
organisms
• Studies genetic, cellular, or reproductive changes in
organisms exposed to specific pollutants
• Many pollutants disrupt the endocrine system
• Glands that produce hormones
• Hormones control most life processes
• Hormone mimics – pollutants that behave like natural
hormones
• Hormone disrupters – pollutants that prevent natural
hormones from functioning normally
• Hormone mimics have been found in male trout
and eels that contained egg-yolk proteins usually
produced only by females
• Found downstream from sewage treatment plants
• Estrogen-like chemicals that induce male fish to make
female proteins
• Come from detergents and urine of women taking
contraceptive pills
• Hormone disrupters interfere with sex hormones
• Phthalates - used in cosmetics like hair dyes and fingernail
polish
• Alligators in a polluted Florida lake had such abnormally
small male sex organs and low testosterone levels that they
could not reproduce
• The herbicide atrazine disrupts sexual development of frogs
• Killer whales and beluga whales are developing
reproductive problems, tumors , and sexual abnormalities
• Imposex in snails
• Imposex – females develop male sexual organs
• Causes sterility and declines in populations
• Tributyltin (TBT)is linked to imposex in dogwhelk snails
• TBT is common additive in antifouling paints
• When TBT was banned for yachts, boats, and fish cages, the
dogwhelk populations bounced back
• Waste disposal remains inadequate
• Wastewater from cities carry oil and toxic chemicals into
waterways
• Waste incineration emits toxic products to the air
• Mining can release toxic contaminants into waterways
• Landfills are leaking
• Some sewage treatment plants release raw sewage into
waterways after heavy rains
• Radioactive waste from nuclear power plants