=======================Electronic Edition========================
RACHEL’S HAZARDOUS WASTE NEWS #380
—March 10, 1994—
News and resources for environmental justice.
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FROGS AND PHILOSOPHY
The decline of frog populations world-wide has stirred dispute in
the media. Like other environmental problems beset with
uncertainties, the simultaneous disappearance of frog populations
from every continent offers the media a vehicle for venting
philosophical views, environmental and anti-environmental. (Just
as the anti-environmentalists now have their own funders, they
also have their own favorite media and writers.)
The NEW YORK TIMES pins frog loss on ozone depletion and
resultant increases in ultraviolet sunlight striking the
Earth. [1] At the other end of the philosophical spectrum, Boyce
Rensberger, an anti-environmentalists’ favorite with the
WASHINGTON POST, suggests that environmentalists caused the frog
loss when they forced government to ban a pesticide that formerly
controlled a fungus that is now running rampant worldwide,
killing off frog populations. [2]
The ozone layer in the stratosphere–6 to 30 miles above the
earth’s surface–filters out deadly ultraviolet radiation from
the sun. Many chemicals, but chiefly DuPont’s
chlorofluorocarbons, diminish Earth’s ozone shield, allowing
increased ultraviolet light to strike the Earth. The TIMES
reported studies showing that ultraviolet light is increasing on
parts of the Earth and that reproduction of some frogs and toads
is diminished by exposure to ultraviolet light. Rensberger
responded with a theory of his own.
For some time now, Rensberger and the WASHINGTON POST have been
selling the idea that ozone depletion, although real, has never
harmed anyone or anything and is getting better all the time.
Rensberger puts his name on stories carrying headlines such as
“After 2000, Outlook for the Ozone Layer Looks Good” and “Decline
of Ozone-Harming Chemicals Suggests Atmosphere May Heal
Itself.” [3] And he writes things like, “In fact, researchers
say, the problem [of ozone loss] appears to be heading toward
solution before they can find any solid evidence that serious
harm was or is being done.” Blaming frog loss on ozone appears
to ruffle Rensberger’s philosophical feathers.
Rensberger’s theory that the ozone layer will fix itself before
anyone or anything is hurt is more wishful thinking than science
reporting. Rensberger himself says that the ozone “holes” over
the North and South poles will not go away until the year 2050 at
the earliest. Even this prediction is optimistic because it
assumes worldwide compliance with the Montreal Protocol, a 1987
international agreement to stop using DuPont’s ozone-destroying
chlorofluorocarbons in cooling systems. A few countries, such as
China, India, Indonesia, and those of the former Soviet Union
–representing 47% of the world’s population –have said they
can’t afford to comply with the Protocols. Whether they will or
not remains to be seen.
Even if everyone phases out chlorofluorocarbons right on
schedule, U.S. Environmental Protection Agency (EPA) is sticking
with its April, 1991, estimate of the skin cancers that ozone
loss will cause. During the next 50 years, EPA says, ozone loss
will cause 12 million skin cancers in the U.S. and 200,000
deaths. Worldwide, a billion (a thousand million) skin cancers
are expected to result from ozone loss, including 17 million
deaths, over the next 50 years.
Rensberger’s new theory on frog loss seems philosophically
consistent with the anti-environmental perspective, but more than
a little implausible all the same. HOMO SAPIENS –modern humans
–have been on Earth for 60,000 years. [4] Most chemical
pesticides have been around for 50 years or less. Frogs have
successfully inhabited the Earth for at least 200 million
years. [5] Rensberger’s theory, that during the past two decades
frogs somehow became dependent on human pesticides for their
survival, is –to put it politely –pretty silly.
The scientific concern about frog disappearances emerged during
the First World Congress of Herpetology at Cambridge, England in
1989. Herpetology is the study of reptiles (snakes, lizards,
turtles) and amphibians (salamanders, toads and frogs).
At the Congress, in the hallways and during coffee breaks,
scientists compared notes and realized that in Colorado and Costa
Rica, in Australia and Africa, frogs are disappearing. Whole
species being studied in the ’60s and ’70s simply disappeared
during the ’80s.
The International Union for the Conservation of Nature (IUCN) by
1991 organized a Declining Amphibian Populations Task Force
(DAPTF), located at Oregon State University in Corvallis. Late
last year the Task Force published, THE STATUS OF AMPHIBIAN
POPULATIONS; A COMPILATION AND ANALYSIS. This authoritative
report leaves little doubt that amphibians–particularly
frogs–are disappearing from locations all over the globe, though
the full dimensions of the problem of course remain sketchy.
What’s responsible for the declines? Journalists like simple
answers and perhaps scientists do too. But there seem to be
multiple complex causes for the loss of amphibians worldwide.
The DAPTF lists the following:
1) “The overwhelmingly reported cause of declines is habitat
destruction, disturbance and fragmentation,” says the DAPTF
status report. In other words, condominiums, parking lots, and
shopping malls are the culprit reported most often. Humans are
wrecking wildlife habitat in a frenzy of what the
anti-environmental movement calls “development.”
2) A close second is pollution –pesticides, acid rain, and other
chemical contamination.
3) Third is the introduction of non-native species of predatory
fish, which disturb the ecological balance of lakes and streams.
4) Drought and flood –both of which seem to be increasing,
worldwide, perhaps in response to global warming (see RHWN #300
AND #301) –are taking their toll on amphibian populations.
5) Eutrophication of ponds (excessive growth of plants, which
depletes oxygen in the water) caused by the modern farming
practice of over-fertilizing, contributes.
In the last three years, two new causes, perhaps related, have
been suggested.
6) The immune systems of some populations of frogs and toads have
somehow been damaged, perhaps by chemical contaminants, perhaps
in combination with extremes of weather and temperature. [6]
Animals with damaged immune systems may fall prey to bacteria and
viruses that they might otherwise withstand.
7) And most recently Robert Stebbins, emeritus professor of
zoology at University of California at Berkeley, has suggested
that amphibian population declines may be caused by environmental
pollutants that mimic estrogens and disrupt the endocrine and
immune systems of amphibians. Stebbins presented his views in a
paper at the Second World Congress of Herpetology in Adelaide,
Australia in January and they will appear again in this month’s
issue of FROGLOG, the journal of the DAPTF in Corvallis. [7]
Stebbins will examine his hypothesis further in a chapter of his
new book, A NATURAL HISTORY OF AMPHIBIANS, to be published this
year by Princeton University Press, he said in an interview. He
wonders aloud whether frogs aren’t particularly susceptible to
damage by hormone-mimicking, endocrine-disrupting chemicals for
some or all of the following reasons:
1) Most or all hormone-mimicking chemicals are soluble in fat;
2) Frogs absorb environmental chemicals through their highly
permeable skin, as well as via digestion;
3) The change from tadpole to frog may release toxins that have
been stored in fat;
4) When emerging from hibernation to breed, amphibians draw
heavily on fat reserves, which may release fat-stored toxins;
5) Females draw upon fat reserves to create the yolk of their
eggs, perhaps again releasing fat-stored toxins into their
systems.
6) The dramatic physical change from tadpole to frog is
hormone-driven and thus could be susceptible to interference by
environmental pollutants (xenoestrogens, or xenobiotics) that
mimic hormones.
7) During the change from tadpole to frog, the creature stops
eating, stressing its whole system.
Of course no one knows what’s really going on in nature.
Scientists produce fragments of information, then try to see
patterns among the fragments. What patterns a reporter sees
depends upon where he or she stands on one basic question that
separates environmentalists from anti-environmentalists: can
humans continue to rearrange and contaminate ecosystems
everywhere without ultimately destroying the ability of the Earth
to support human life? Those with an abiding faith might answer,
“Humans are not threatening anything serious. Even if frogs ARE
disappearing, we’ll simply learn to live without them. All is
well.”
Environmentalists, on the other hand, are likely to stand with
biologist Rachel Carson who in SILENT SPRING (1962) wrote,
“…[T]he new chemicals come from laboratories in an endless
stream; almost 500 annually find their way into actual use in the
United States alone. The figure is staggering and its
implications are not easily grasped –500 new chemicals to which
the bodies of men and animals are required somehow to adapt each
year, chemicals totally outside the limits of biologic experience.
“These sprays, dusts, and aerosols are now applied almost
universally to farms, gardens, forests and homes. Can anyone
believe it is possible to lay down such a barrage of poisons on
the surface of the earth without making it unfit for all life?”
                
                
                
                
    
–Peter Montague, Ph.D.
===============
[1] Carol Kaesuk Yoon, “Thinning Ozone Layer Implicated in
Decline of Frogs and Toads,” NEW YORK TIMES March 1, 1994, pg.
C4, citing J.B Kerr and C.T. McElroy, “Evidence for Large Upward
Trends of Ultraviolet-B radiation Linked to Ozone Depletion,”
SCIENCE Vol. 262 (November 12, 1993), pgs. 1032-1034. See also
Mario Blumthaler and Walter Ambach, “Indication of Increasing
Solar Ultraviolet-B Radiation Flux in Alpine Regions,” SCIENCE
Vol. 248 (April 13, 1990), pgs. 206-208.
Descriptor terms: anti-environmental movement; wise use; frogs;
amphibians; toads; pesticides; fungi; fish; species loss; ozone
depletion; ultraviolet light; solar radiation; washington post;
international union for the conservation of nature; iucn;
declining amphibian populations task force; daptf; robert
stebbins; boyce rensberger; immune disorders; endocrine
disrupters; hormones; estrogens; estrogen; fat; reproductive
health; reproduction; rachel carson; silent spring;