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Environment
and Disease
Chemicals and
Human Disease
  We know that chemicals can cause many
human diseases. l think that this concept is best established
with tobacco smoking, the major cause of lung cancer. Another
major cause of disease is the compound asbestos. It causes mesothelioma,
(an unusual tumor of the linings of the chest and abdominal
cavity), lung cancer, and increases in gastrointestinal cancer
as well as asbestosis, a chronic fibrous disease of the lung.
Since we use 600,000 tons of asbestos every year in the United
States, this compound presents a major health problem.
Recently, we discovered
a number of chemicals that cause sterility, particularly in
men. Within the last three or four years, we have established
that two pesticides, kepone and dibromochloropropane, cause
sterility in men. Currently, we are investigating new evidence
that benzene, a major industrial chemical and a component of
unleaded high-test gasoline, also can cause sterility.
 
In addition, the
experiences of workers at a kepone-producing plant in Hopewell,
Virginia, have provided dramatic evidence that chemicals can
cause neurological diseases. Kepone inhaled by workers may have
become embedded in their brains causing nervous tremors, twitching
and flickering eyes.
These are just a
few examples of the problems created by the everincreasing production
of synthetic organic chemicals. In 1918, about 10 million pounds
of synthetic organic chemicals were produced, used, and disposed
of in this country. By 1936, production was up to 860 million
pounds a year. The numbers have increased dramatically over
the years: 1941, 2 billion; 1944, 37 billion; 1947, 38 billion;
1961, 100 billion; and 1979, 300 billion pounds of synthetic
organic chemicals were made, used and disposed of in the United
States. This figure amounts to nearly 1,700 pounds of chemicals
for every man, woman, and child in the United States.
  We have been exposed to a variety of these
chemicals. The following examples illustrate the pervasiveness
of this exposure. In the late 1960s, when DDT was used extensively,
blood and urine levels of this chemical were high in the people
tested. These levels-now are decreasing, nearly 10 years after
use of the chemical was banned. Pentachlorophenol is a wood
preservative used around boatyards, on poles, and on wood that
has contact with the ground. Exposure to pentachlorophenol is
particularly dangerous because commercial samples of this preservative
contain traces of the dioxins, which can be lethal. In the early
1970s, some residents of Hawaii, exposed to much marine activity
and wood preserving, were found to have levels of pentachlorophenol
in their urine. Finally, although the polychlorinated biphenyls,
known as PCBs, virtually have been banned, our body levels of
the chemical remain constant.
  Furthermore, enormous amounts of PCBs are
in the environment. PCBs enter the food chain and into human
diets primarily through consumption of certain fresh water fish.
Infants as well as adults can be exposed to these chemicals.
Polychlorinated biphenols can be passed to babies through breast
milk.
On to Cancer and Chemicals
Back to Environment and Disease Home Page
National Institute of Environmental Health Sciences
National
Institutes of Health.
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