| |
A convincing body of
evidence indicates that a large proportion of human developmental
disease is caused by environmental agents that damage the genetic
constitution of somatic cells. These agents-chemicals, radiation,
and viruses-produce congenital malformations, cancer, and a variety
of more subtle effects on health and longevity.
Chemical
substances that induce mutation occur in widely divergent chemical
groups, ranging from simple compounds such as formaldehyde to
complex ones such as alkaloids. Many of these chemicals are carcinogenic
(cancer producing). A test devised by the U.S. biochemist Bruce
Ames has shown that about 90 percent of cancer-producing organic
compounds are also mutagens and that compounds that are noncarcinogenic
are also nonmutagenic. It follows, then, that mutagenicity, both
germinal
and somatic,
is a property of most carcinogenic environmental exposures.
Since
these chromosome changes (somatic mutations) represent a most
important cause of serious human disease, including cancer, it
follows that a test is needed that can more quantitatively detect
single-gene mutations and chromosome deletions and loss. A short
and relatively simple test for making such measurements has been
developed utilizing stable human-Chinese hamster ovary hybrid
cells that have retained a single human chromosome (number 11)
not needed for cell reproduction.
Exposure
to chemicals is ubiquitous in industrial societies. It has been
estimated, for example, that more than 50,000 chemicals are in
common use in the United States. Most of these compounds
have
not been tested for mutagenicity. The total exposure to mutagenic
chemicals is thus unknown, but it undoubtedly presents a definite
public health risk. Although the individual is often powerless
to avoid exposure to widely used chemicals, there are notable
examples of mutagens to which people voluntarily expose themselves.
Prominent among these are alcohol, which can function as a teratogen
(i.e., can cause birth defects), and cigarette smoke, which has
both teratogenic and carcinogenic effects.
Gina
Kolata
|
|