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Pesticides Linked to Increase in Canine Cancer and Hermaphroditic Frogs

Friday, March 4, 2005

Spikes in bladder cancer in dogs and hermaphroditic amphibians show a connection to increased pesticide use in the United States, two new studies show. The Cleveland Plain Dealer reports that a study at Purdue University revealed that Scottish terriers exposed to lawns or gardens treated with herbicides and insecticides showed a significant increase in the risk of bladder cancer over dogs exposed to untreated areas. The risk of bladder cancer was higher in dogs exposed to the most commonly used agricultural chemical, phenoxy acid herbicides.

Phenoxy acid is an active ingredient in 2,4-D, a common herbicide that the EPA says is safe. However, the EPA doesn’t require that inert ingredients be listed on the labels of lawn products, and those compounds – which contain metals, petroleum-based solvents and cadmium – cause cancer.

A follow-up study will be conducted on children and dogs exposed to lawn chemicals to determine if the chemicals are in their systems, at what levels, and the nature of the exposure more than three days after their lawns are chemically treated.

The University of Illinois at Urbana-Champaign also released a 150-year study showing a heavy increase in hermaphroditic frogs during periods of widespread pesticide contamination, the Los Angeles Times reports. This condition was rare until the 1950s, when the chemicals were most heavily used.

The phenomenon, which has also been observed in Florida alligators, is most obvious in the decline of cricket frogs in Chicago and other regions in the 1960s. DDT, PCBs and other pollutants are theorized to have had mutagenic effects that reduced the number of female frogs and caused the population to drop dramatically.

Unfortunately, scientists can’t tell if banning DDT and PBCs has made a difference in current populations, because where the animals were mutating into hermaphrodites the populations died out, and there are no longer any samples to collect. They do suspect that atrazine, a popular corn herbicide still in use, may also be responsible. Frog populations are low in central Illinois, where the herbicide is most used, and higher in southern areas, where it isn’t.

Pesticides may cause a variety of health problems in humans, including premature puberty in girls and reproductive diseases. The Environmental Working Group has petitioned the EPA to halt a study called CHEERS (Childrens’ Environmental Exposure Research Study) that offers families $970, a T-shirt, a bib and a videocamera to expose their children to household pesticides. The American Chemistry Council provided $2 million of the $7 million fund for the study.

View EWG’s work on pesticide testing on humans.

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