though less Striking, data were ob-
tained when the same tests were run
on two other herbicidal compounds
that are related to each other but nor
to atrazine. These results point to the
desirability, even the necessity, of
proceeding with equivalent investiga-
tions on still other major herbicidal
chemicals.

Plewa and Gentile have continued
their analysis of the active material in
the atrazine metabolite. On thin
layers of silica gel, the components
of the corn plant extract can be sepa-
tated so as to yicld at least two active
mutagens that work on test yeasts and
the above-mentioned bacterium.
These mutagens are water soluble and
probably act b

substitution int

p DNA had previously
been noted by other investigators,
Even more suggestive in this connec-
tion are other herbicides built of sub-
stances that are actually modifi-
cations of one of the DNA bases.
Subjected to the Plewa-Gentile type
of analysis, and in light of the experi-
ence with atrazine, these herbicides

might also be expected to show muta-
tional activity,

This work does not, of course,
Prove that atrazine-treated corn
causes mutations in humans. For one
thing, the active metabolic product
might be broken down by the acidic
conditions of the human stomach or
might never be absorbed from the
gastrointestinal tract into body tissue,
Even if the active Material were to
enter the body, it might readily be
detoxified by the liver or some other
body decontamination Center. [t is
also possible that, despite its effect on
corm and microorganisms, the sub-
stance might not act on humans or

animals at a hat however, would
be unexpected. since DNA is similar

in all living organisms, and what af-

fects the DNA of one creature should
affect that of all.

ft appears likely that we will see a
marked extension of the kind of test-
ing initiated by Plewa and Gentile.
The results may put pressure on the
Environmental Protection Agency,
the Food and Drug Administration,
and the National Institutes of Health
to take a position on the continued use
of atrazine and related compounds. In
the meantime, the organic farming

3

aficionados, who grow only products
produced without herbicides or pesti-
cides, would appear to be taking the
Most prudent course, at leact from the
point of view of public health.

(While no sensible person would
claim that we should stop using all
chemical compounds in agriculture,
mounting evidence indicates that we
have not been sufficiently careful in
screening these agents before their
widespread production and extensive
use.) Through the serious partici-
pation of industry and government, as
well as the technical and environ-
mental sciences, it should be possible
to find a balanced approach in devel-
oping new testing criteria and a better
answer to ‘how safe should safe
be?'' (More stringent criteria may
well lead to screening programs that
are more complicated, more expen.
sive, and longer than those now in
practice. Under these circumstances,
alternatives to the use of herbicides
and pesticides may become more fea-
sible in terms of economics as well
as public health.)

Arthur W. Galston teaches biology at
Yale University,

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