Lipgary ho 79

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by Arthur W. Galston

Bios

How Safe Should Safe Be?

The screening of new
herbicides and other
synthetic compounds must
be expanded to include
the possibly mutagenic
effects of their

metabolic by-products

Modern industry, agriculture, and
Medicine float on a sea of synthetic
chemical compounds. Every year
thousands of such new products are
devised. Each purports to solve some
human problem or satisfy some
human need better than its predeces-
sors. Some are uneconomic to make
and never reach the production line or
sales counter. Others are weeded out
between the testing laboratory and the
production line because they are ob-
viously dangerous or toxic to human
life. But even those that get through
the screens imposed by private com-
panies and the various local, state,
and federal agencies, cannot auto-
matically be considered safe. In fact,
an alarming number of compounds
and processes, long accepted and
used, have recently been found to
have unexpected and deleterious ef-
fects on biological systems. Thus it
has become imperative to inquire
Closely into the criteria that are, and
ought to be, employed to safeguard
the public health and well-being: con-
tinually to explore the question,
How safe should safe be?

Developing these criteria is not en-
tirely an exercise in rational, dispas-
sionate analysis. More und more, the
process involves reconciling the often
conflicting interests of business, ugri-
culture, and the environmentalists.
Known benefits ure carefully weighed

against demonstrated or possible side
elfects. The final choices are both
subjective and evaluative. DDT is an
example. The fact that it can wipe out
malaria-beuring mosquitoes must be
balanced aguinst its inadvertent de-
struction of useful insects, such as
bees and others serving as sources of
food for birds. Similarly, the drop in
crop productivity and loss of income
that result from the banning of DDT
must be balanced against the possi-
bility that its slow biodegradability

may ultimately produce new dangers
to man. There are still unanswered
questions concerning DDT, but while
they are being worked out, countries
where insect-borne hurnan diseases
are.still a major problem cannot be
expected (o ban the compound.

’ Against this background, a recent
discovery by two brand-new Ph.D.s
is of particular interest, for by apply-
ing a known but neglected approach
to the testing of herbicides, they have
raised doubts about the alleged safety
of most agricultural. chemicals in
major use today. Michael J. Plewa of
the Department of Agronomy of he
University of Tilinois and Jaiacs M.
Gentile of the Department of Human
Genetics at Yale University have just
produced evidence that atrazine, ihe
most widely used herbicide income

felds. gives rise t0 metabolic prod-

ucts that Cause mutations, and possi-
bly cancer. in laboratory a y_animals, [n= ,
ependent substantanon of — their
claims, which appears to be at hand,
could lead to a massive reappraisal of
the procedures normally emploved
for certifying as safe those chemicals
designed to be used in agriculture.
How could such a pernicious effect
have been overlooked when atrazine
was first tested? Atrazine itself, pro-
duced by Ciba-Geigy, a Swiss-based
corporanion, had a clean bill of

health, When Ted to experimental ani-

mals for detection of toxicity symp-
toms, to microorganisms for detec-

* tion of mutagenicity, and to tissue

- Cultures for detection of possible

Nata SRY > “Apr.

carcinogenicity (by induction of can-
Cerous Overgrowths), atrazine was in-
nocuous. If it is first supplied to cora
plants, however, chemical extracts of
the leaves and Kernels of such plants