Raising new questions about the environmental risks of some widely used farm chemicals, scientists are reporting today the first evidence linking agricultural runoff to grotesque hind-limb deformities in frogs.Two frogs (upper left and upper right) have normal limbs, while the other four have deformities.
Penn State University photo by Joseph Kiesecker via Associated Press
Researchers said frogs appear to be made more vulnerable to a common parasite when exposed to the pesticides atrazine and malathion. The parasite, a burrowing trematode worm, tends to infect the hindquarters of developing tadpoles.
Atrazine is part of a family of chemicals that rank among the world's most widely used weed killers.
Malathion is commonly applied to control mosquitoes and other insects, and pharmaceutical grades are approved for killing head lice.
Both products are controversial but considered safe for commercial use in the United States.
Now, effects of these and other chemicals on the environment are coming under new scrutiny. This is most certainly an early warning of health problems affecting humans.
Now, effects of these and other chemicals on the environment are coming under new scrutiny. This is most certainly an early warning of health problems affecting humans.
At last count, wild frogs with missing or extra hind limbs have been observed in at least 43 states and five Canadian provinces.
It is important to know that for malathion and atrazine; significant effects were seen even at concentrations considered safe for drinking water by the Environmental Protection Agency.
original article by: CARL T HALL / SF Chronicle 9jul02
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