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E-M:/ Re: Pestidides and Amphbians



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Enviro-Mich message from "david zaber" <dzaber@gateway.net>
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Michiganders, 

The following is a posting describing some research and thoughts on the
global decline of amphibians.  Michigan is home to many wonderful
amphibians despite the tragic destruction of the state's public forestlands
and wetlands of all ownerships.  

The worldwide decline in amphibians did not seem to bother the wildlife
biologist from the Waterloo Recreation Area in Jackson and Washtenaw County
when I was living there.  Not only did the biologist refuse to conduct any
surveys for wildlife in areas that were being cut for new roads into the
park, the cut over areas were sprayed with herbicides and then planted in
corn for deer browse.  The biologist failed to justify his corn planting
program.  First he said it was for deer browse, then he said it was to lure
deer off private property, then he said it was for turkey browse, then he
said it was to keep the area in early successional stages.  The biologist
repeatedly refused to walk the site with me, despite my correspondence with
him for several years on various issues, including the management of the
tract in question.  This was typical DNR methodology and it seems to have
worsened over the years.  

Unfortunately, the site was extremely rich in amphibians and I used the
area for aquatic ecology lab sections fieldtrips.  We saw numerous species
of wildlife, including several species of frogs and turtles.  The pond on
the site was fed by surface runoff which greatly increased the probability
that the herbicide used to kill the vegetation for corn planting would run
into the pond.

By the way, I use the term Biologist, very, very loosely in the above post.
 Any biologist worth their salt would be very hesitant to continue to
increase the browse for deer in a region with so many deer-related problems
(i.e. car accidents, overbrowsing, lyme disease, etc.)  Use of herbicides
near a runoff-fed pond was simply irresponsible and I hope that today's
biology students have more sense then the biologist for this region.

We may want to start a new category of state worker: Industrial Deer
Producer.

Enjoy

David John Zaber
904 Glaizewood Court
Takoma Park, MD 20912
dzaber@gateway.net


Pesticides and Amphibians

Strong evidence is emerging that reproduction and development 
in aquatic animals is threatened by pesticides. A new study, 
released jointly by researchers at the Canadian Wildlife 
Service, the Redpath Museum at McGill University, and the 
Ontario Veterinary College explores this connection further. 

The researchers surveyed frog and toad populations in 
agricultural areas in the St. Lawrence Valley, Canada, for 
developmental defects such as limb deformities. They 
compared amphibians that live in agricultural areas where 
pesticides are applied regularly to those that live in areas 
where little pesticide use has occurred. Many frogs had extra 
legs growing from their stomachs and backs; other frogs had 
only stumps for hind legs or fused hind legs. Some frogs were 
missing eyes or had extra eyes; others were missing toes or 
had extra ones. The scientists examined some frogs for
internal effects and found enlarged and diseased livers, as 
well as female organs inside frogs that otherwise appeared to 
be male.

After observing nearly 30,000 frogs and toads, they 
determined that the incidence of limb deformities in animals 
undergoing metamorphosis between tadpole and frog is 
7% overall in agricultural habitats, but only 1.5% in the 
non-agricultural areas. The prevalence of deformed tadpole-
frogs was between zero and 67% in pesticide-contaminated 
sites but only between zero and 7.7% in the control sites. 
The deformity rate of adult frogs from agricultural areas was 
2.6%, just slightly higher than that for unexposed population 
at 1.5%. This indicates that many of the deformed tadpole-
frogs did not survive to adulthood, a fact that is likely 
responsible for the overall drop in frog and toad populations 
in the area. Canada has 45 frog and toad species and of these 
17 are in decline, largely due to human activities that
destroy habitat or contaminate water.

One of the researchers, Dr. Martin Oulette, is convinced that 
the damage is due to pesticides. On a farm near St. Charles 
in the St. Lawrence Valley, every frog he found was deformed. 
"We have to know why the frogs are deformed and why they are 
dying," says Oulette. "We're also living in the St. Lawrence 
Valley and we put the food coming from there on our tables."

Researchers have been investigating deformities in amphibians 
for a number of years. In 1994, Florida alligators were shown 
to have been feminized by endocrine-disrupting pesticides 
that interfere with normal development. In many species, 
including amphibians, fish and humans, the endocrine and 
thyroid hormones control the process of development. Exposure 
to hormone-mimicking substances such as many commonly used 
pesticides results in interrupted development, as in the case 
of the Florida alligators, where the incidence of deformed 
reproductive organs was extremely high due to exposure to the 
pesticide dicofol. Because amphibians live in the water, it 
is clear that they are the "front line" when it comes to
exposures.

More needs to be known about endocrine-disrupting substances 
before we can fully evaluate their potential for 
environmental damage. Scientists already suspect a link 
between endocrine disruptors such as PCBs and declining sperm 
counts, testicular cancer and genital defects in human males. 
The World Wildlife Fund recently published a paper entitled 
"Chemicals the Compromise Life: A Call to Action" 
highlighting work on endocrine-disrupting chemicals that has 
taken place since the "Our Stolen Future" was published in 
1996 (see PANUPS Resource Pointer #184).

A comprehensive list of the chemicals that are responsible 
for these problems is not yet available nor is there adequate 
information about the specific effects of these chemicals on 
different species. Based on the recommendations of the
Endocrine Disruptor Screening and Testing Advisory Committee 
(EDSTAC) released in September 1998, the U.S. Environmental 
Protection Agency is implementing an extensive testing 
program to screen approximately 62,000 chemicals for their 
endocrine-disrupting potential by the year 2000. The two-
tiered screening plan gives high priority to chemicals with 
widespread exposure at the national level, as well as 
those that cause high exposures in certain groups,communities 
or ecosystems. 

Sources: Martin Ouellet, et al., "Developmental abnormalities 
in free-living anurans from agricultural habitats," Canadian 
Wildlife Service, October 1998; 
http://www.qc.ec.gc.ca/faune/faune/html/malformations_e.html.
The Ottawa Citizen Special Report: Science and the
Environment, Donna Jacobs, September 27, 1998. 
U.S. Environmental Protection Agency EDSTAC recommendations: 
http://www.epa.gov/opptintr/opptendo/.
Contact: PANNA.

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49 Powell St., Suite 500, San Francisco, California 94102
Phone (415) 981-1771
Fax (415) 981-1991
Email: panna@panna.org  
web site www.panna.org/panna/ 

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