Frogs are sensitive to pollution, because they live at the meeting
of
two environments, land and water, and they can easily absorb pollutants
through their skin. Because frogs are so sensitive to the environment,
pollution of the land and water may be contributing to the mutations
and
decline in population of the frogs and other amphibians and reptiles.
The National Institutes of Health's National Institute of
Environmental Health Sciences (NIEHS) performed a test on
Minnesota’s water. The test, which takes four days to complete, was
run multiple times using dilutions of the water from the Minnesota
sites ranging from zero to 100 percent. At concentrations above 50
percent, a high percentage of the frog embryos developed in the water
showed a wide range of abnormalities, similar to what has been
observed in frog larvae in the field in Minnesota since 1995.
Moreover, the number of abnormalities increased with the
concentration of the water from Minnesota sites. Water from "normal"
sites (no deformed frogs found) did not produce harmful effects in
the frogs.
A Swiss team led by Heinz-Ulrich Reyer of the Zoological Institute
at
the University of Zurich found that triphenyltin, a agricultural
chemical used to control blight, causes deformity and death in
several species of frog. Triphenyltin slowly degrades in water and
is highly toxic to many aquatic organisms. The researchers believe
that the chemical disrupts the tadpole’s central nervous systems, and
that because the chemical affects the development of frogs, it could
drive local populations to extinction.