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GLIN==> Frog deformities linked to pesticide/fungicide

Posted on behalf of Gary Casper <gsc@mpm.edu>

>From Milwaukee Journal Sentinel, Oct. 6, 1999:

Pesticide linked to deformed frogs, studies indicate

Pesticides used in agriculture have been linked with some frog deformities
in Minnesota, according to two new studies.

The studies are the culmination of 18 months of lab tests on pond water
from Minnesota and elsewhere. The results suggest that a combination of
appears to be causing malformations of the frogs' limbs, eyes, mouths and
other parts.

Researchers said the mystery of the deformities and whether the causes
could also affect humans were not resolved in the studies, published in the
issue of the journal Environmental Toxicology and Chemistry.

"At this point we can't say that this is something that applies only to
frogs," said Jim Burkhart, co-author of the studies and a biochemist at the
Institute of Environmental Health Sciences in Research Triangle Park, N.C.

Water and sediment samples were taken from six Minnesota ponds, three of
which had produced lots of deformed frogs. The locations weren't named. In
analyzing the water, scientists found chemicals, several of which are
products of pesticides.

The NIEHS study did not rule out other potential causes of deformities,
such as ultraviolet radiation or parasites.

In the other study, scientists took Minnesota pond water and used it to
raise frogs. The water from cleaner sites did not cause problems, but water
sediment from ponds in which deformed frogs were found caused the same
kinds of malformations, Burkhart said.

Deformities included skull and face defects and abnormal development of the
mouth and eyes. Filtering the water to remove some of the chemicals reduced
the deformities significantly.

The most obvious deformities seen in Minnesota frogs have been twisted
spines or malformed hind limbs and other problems such as webbed skin or
missing digits.

Maneb, a fungicide, and propylthiourea, a pesticide breakdown product,
induced some types of hind limb defects in the lab frogs.

Burkhart said the most intriguing finding was that some of the compounds
appear to be more toxic in natural waters in Minnesota than in the solutions
prepared in the labs.

Compounds segregated and mixed with lab water produced deformities, he
said, but when they were mixed with "clean pond" water, the deformities were
much worse.

"The question we're asking is, what is the interaction between some of
these manmade compounds with the nontoxic compounds of natural origin at
of these sites?" he said.

Doug Fort, a co-author of the studies and a toxicologist at the Stover
Group, a private research and development firm in Stillwater, Okla., said
the research
is more suggestive than definitive.

He said several of the chemicals suspected of causing deformities appear to
have one similarity: They affect the thyroid, the primary gland responsible
growth, maturation and development in most animals, including humans.

When thyroid hormones were added to some of the experiments, he said, the
number of hind limb defects declined.

Judy Helgen, a wetlands biologist for the Minnesota Pollution Control
Agency, called the research "a solid step in the direction we need to go."

"We're still open to other hypotheses, but it certainly looks from these
(scientific) papers like chemicals or some combinations that include
chemicals are
responsible for different types of malformations," she said.

During the past four years, deformed frogs have also been reported in
several other states, including Wisconsin, Vermont, Oregon and California,
and in
Gary S. Casper
Collections Manager, Herpetology & Ichthyology, Milwaukee Public Museum
Associate Coordinator, US Declining Amphibian Populations Task Force
Wisconsin Herpetology Homepage
please direct correspondence for Gary S. Casper to:
Vertebrate Zoology Section, Milwaukee Public Museum
800 W. Wells St., Milwaukee, WI 53233
voice (414)278-2766   fax (414)278-6100   E-mail gsc@mpm.edu

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