startling expressions of possible environmental degradation have been found in Minnesota, us . Deformed frogs have been seen in more than 100 sites in 54 of Minnesota's counties. At a recent conference of scientists convened by the Environmental Protection Agency ( epa ) in Duluth, Minnesota, the recurring thought was whether the presence in such large numbers of deformed frogs was a foreboding of possible similar occurrences in humans as well. Reports of deformed frogs have also poured in from other parts of the state.
The deformed frogs were first discovered by school children during a field trip in south-central Minnesota. The amphibians were either found with missing or withered hind legs or extra limbs. There were others which had legs webbed together with extra skin or with legs fused to the body. A particular frog which had only a single eye was found to have its second eye growing inside its throat.
The highest incidence of deformity was found among the mink frogs -- 50 per cent of the total -- and these frogs spend most of their time in water. The least aquatic of the species, American toads and wood frogs, had the lowest rates of deformity of under five per cent. As the deformed frogs were found in and around ponds that had been excavated recently, scientists speculate that contaminants from the bottom of the ponds could have surfaced to the top.
Tests on the tissues of deformed frogs have revealed that genetic mutation was not the cause. Developmental abnormalities could have occurred in the egg and tadpole stages lending more credence to the belief that external environment was primarily responsible for the malformations.
At the conference, the possibility of local farm pesticides received more attention. Other causes being considered are viral or bacterial diseases, presence of heavy metals known to cause birth defects, acidification of water and also increasing ultra-violet radiation. However, Judy Helgen, a research scientist and water quality expert with the Minnesota pollution agency and part of the investigative team, believes that a chemical of some kind could finally be the culprit. Said Joe Tietge from the epa , "If it turns out to be a chemical problem, then we will have to do a risk evaluation for humans. After all, frogs are vertebrates and so are we."
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