From July 15, 2002
New Study Finds
Agricultural Pesticides Play an Important Role in Frog Leg Deformities
Penn State University Researcher Joseph Kiesecker found that wild tadpoles exposed to low-level agricultural chemicals along with the deformity causing parasite trematode were five times more likely to develop leg deformities than frogs only exposed to the trematode. The presence of the pesticides are thought to weaken the frog's immune system thereby making them more susceptible to infection by the parasites.
In the lab, Dr. Kiesecker found that pesticide exposed tadpoles had higher rates of parasitic infection and a matching reduction in white blood cell production, a commonly used indicator of a weaken immune system. All of the pesticide concentrations investigated in the experiment were below EPA-recommended levels for safe drinking water.
"If it's true that commonly used pesticides compromise the immune system of a vertebrate organism, which is what the findings suggest, then we're looking at a much bigger problem then deformed frogs" said David Gardiner of the University of California at Irvine.
Although trematode does not infect humans, many parasites do. A notable example is Schistosoma, which causes 200 million cases of disease including over 20,000 deaths each year.
Included in the investigation was the herbicide atrazine, which has been separately linked to sexual deformities in frogs.
More information can be found at: http://www.science.psu.edu/alert/Kiesecker7-2002.htm.
More information about atrazine and frog deformities can be found in the daily news archives under Cancer and other Health Problems.