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#246 - The False Promise Of Pesticides, 13-Aug-1991

"The ozone layer, which protects living things from the Sun's harmful
ultraviolet rays, has been depleted in many areas of the globe, and at
the latitudes of the United States the loss is proceeding twice as fast
as scientists had expected, the [U.S.] Environmental Protection Agency
announced [in April].

"The agency said the declines measured in the late fall, winter, and
early spring amounted to 4.5 to 5 percent in the last decade.

"'It is stunning information,' William K. Reilly, the agency's
Administrator, said in an interview after the announcement in
Washington. 'It is unexpected, it is disturbing....'

"According to agency calculations based on the new ozone findings, over
the next 50 years about 12 million Americans will develop skin cancer,
and more than 200,000 of them will die. Under previous assumptions,
only 500,000 cancer cases and 9,300 fatalities were forecast....

"Scientists say that for every 1 percent decline in the high-altitude
ozone shield, 2 percent more ultraviolet radiation reaches the earth's
surface. Besides skin cancer, the harmful ultraviolet radiation can
cause eye cataracts. Scientists say it can also affect the human immune
system adversely, that it harms the ability of phytoplankton, tiny
plants at the basis of the oceanic food chain, to reproduce; that it
can damage some crops and wild plants." --NEW YORK TIMES April 5, 1991,
pg. 1, D1.

Thus readers of the NEW YORK TIMES in April learned that ozone
depletion is now proceeding rapidly in the atmosphere above the United
States. For roughly 450 million years, the ozone shield--10 to 30 miles
high in the sky--has protected the surface of planet Earth from
ultraviolet radiation streaming in from the sun. Now chemicals called
CFCs, released from refrigerators and air conditioners, are wafting
upward, destroying the protective ozone in the stratosphere, allowing
ultraviolet light levels to increase on the surface of the Earth. In
sufficient quantities, ultraviolet light is a potent disinfectant,
killing everything it strikes.

And so a problem that only three years ago seemed confined to an ozone
"hole" over the ant arctic is now recognized as a world-wide calamity
that will cause skin cancer in caucasians, will cause eye cataracts and
immune system disorders in humans of all races, will interfere with the
most fundamental underpinnings of oceanic food chains, and will disrupt
wildlife reproduction in other ways that are poorly understood.
Furthermore, the problem is developing twice as rapidly as scientists
had predicted just last year, indicating that scientists--15 years
after the National Academy of Sciences in Washington, DC, declared this
a serious problem worthy of urgent attention--do not yet understand the
problem sufficiently well to predict its course correctly. In this
business of dismantling the life-support systems of the Earth, we are
learning as we go.

Just this year, scientists seem to be reaching agreement that ozone
loss is connected to another worldwide phenomenon that was first
noticed in 1989. Scientists have reported simultaneous wildlife losses
in places as far apart as California, Australia, Brazil, and Europe. It
may sound silly at first, but amphibians--salamanders, toads, and
frogs--are declining, disappearing, and becoming extinct at
unprecedented rates world-wide. Increased ultraviolet light is now
thought to be one important cause, though by no means the only one.

Dr. Henry Wake, a biologist from University of California at Berkeley
chaired a panel of 20 experts for the National Research Council
(Washington, DC) in early 1990. Dr. Wake compares the loss of frogs to
the 19th-century coal miner's canary--when the canary died, it was a
warning sign that the air in the mine had grown hazardous to humans. So
with frogs, says Dr. Wake: "If frogs and salamanders are dying off in
synchrony [at the same time], there's a message there for us," says Dr.
Wake. (NY TIMES Feb. 20, 1990, pg. C4; SCIENCE NEWS Feb. 24, 1990, pg.
116, and March 3, 1990, pg. 142.)

The truth is, amphibians are rapidly disappearing from many ponds,
rivers, mountains, and rain forests around the world, including places
that are not very polluted. Dr. Wake says, "They are disappearing from
nature preserves in the most pristine sites of Costa Rica, Brazil,
Yosemite, Sequoia and Ile Royale National Parks [in the U.S.]. Meadows
where frogs were as thick as flies are now silent," he says.

Individual scientists had been noticing the decline of frogs but it
wasn't until 1989 that they compared notes at a global conference and
discovered that reports of local losses were coming in from all over
the world. Some scientists had refrained from reporting their
observations of loss and extinction for fear that younger colleagues,
or even children, would find live specimens of frogs reported extinct.

All the reasons for the decline of amphibians are not understood. In
some cases, it's loss of habitat. Frogs that used to live in Japanese
rice paddies now find golf courses instead. In the U.S., frogs return
to ponds only to find condominiums. Stocking lakes and ponds with
edible fish, particularly in the western U.S., wipes out frogs when
fish eat their tadpoles.

But there's something going on besides direct human intervention. Dr.
David Bradford of UCLA reports that in the 1970s he found ponds in the
High Sierras containing more than 800 adult yellowlegged frogs and 1500
tadpoles. In 1990, he checked 38 lakes and found frogs in only one.

A leading cause of such declines may be acid rain and acid snow. The
spring thaw brings a shock of acid water into mountain streams, killing
sensitive creatures in the early stages of life.

Another source of problems is pesticides, including those that are
banned for sale in the U.S. but which are still manufactured here and
shipped overseas. Many of them, sprayed abroad, travel on the wind and
rain down on U.S. soil; some see in this an ironic and fitting gift to
us from the developing world, but for frogs and salamanders it
represents apolitical destruction and death.

Amphibians are particularly sensitive to chemical pollution because
they spend part of their life-cycle on land and part immersed in water;
furthermore, they breathe through their skin. Toxic heavy metals and
pesticides building up in aquatic food chains, plus a hefty dose of air
pollution may be what's killing some frogs, toads, and salamanders.

The latest information is that many researchers now believe that
increased ultraviolet radiation may be affecting frogs' eggs, which
float on the surface of the water, absorbing sunlight. Too much
ultraviolet light evidently interferes with the ability of egg cells to

What are Humans Doing About It?

The International Union for the Conservation of Nature (IUCN) has
recently set up a "Task Force on Declining Amphibian Populations,"
located in Corvallis, Oregon. They are developing a worldwide network
of scientists who will document the destruction of amphibians as the
ominous global trend unfolds. (SCIENCE Aug. 2, 1991, p. 509.)

Back in Washington, President Bush has steadfastly refused to force an
aggressive phase-out of ozone-depleting chemicals. Furthermore, Mr.
Bush and Vice-President Quayle recently announced they are reversing
U.S. policies established to protect wetlands. Under pressure from some
of the nation's wealthiest lobbyists, the Home Builders Association,
Mr. Bush will open millions of protected wetlands to development. (NY
TIMES Aug. 3, 1991, pgs. 1, 25.)

For its part, DuPont, the company that invented, patented, and sold the
CFCs that are bringing ruin to the Earth, has developed only one
problem in recent years: managing all the money that is pouring in. As
CFCs are slowly phased out, they become scarcer and their price is
rising on the world market. Organizations dependent upon refrigeration
are willing to pay the rising cost of CFCs to maintain their
operations, and thus DuPont is reaping literally billions of new
dollars each year in windfall profits. (NY TIMES April 21, 1988, pg.

--Peter Montague


Descriptor terms: ozone layer; global environmental problems; epa;
william reilly; studies; immune system; skin cancer; cancer; eyes;
oceans; food chain; habitat destruction; cfcs; national academy of
sciences; amphibians; wildlife; costa rica; brazil; yosemite national
park; sequoia national park; ile royale national park; national parks;
conferences; japan; rice paddies; heavy metals; air pollution;
international union for the conservation of nature; george bush;
wetlands; home builders association; dupont;