Long-term Pesticide Exposure May Increase Risk of Diabetes
Posted Jun 16 2008 6:13pm
Licensed pesticide applicators who used chlorinated pesticides on more than 100 days in their lifetime were at greater risk of diabetes, according to researchers from the National Institutes of Health (NIH). The associations between specific pesticides and incident diabetes ranged from a 20 percent to a 200 percent increase in risk, said the scientists with the NIH’s National Institute of Environmental Health Sciences (NIEHS) and the National Cancer Institute (NCI).
“The results suggest that pesticides may be a contributing factor for diabetes along with known risk factors such as obesity, lack of exercise and having a family history of diabetes,” said Dale Sandler, Ph.D., chief of the Epidemiology Branch at the NIEHS and co-author on the paper. “Although the amount of diabetes explained by pesticides is small, these new findings may extend beyond the pesticide applicators in the study,” Sandler said. Some of the pesticides used by these workers are used by the general population, though the strength and formulation may vary. Other insecticides in this study are no longer available on the market, however, these chemicals persist in the environment and measurable levels may still be detectable in the general population and in food products. For example, chlordane, which was used to treat homes for termites, has not been used since 1988, but can remain in treated homes for many decades. More than half of those studied in the National Health and Nutrition Examination Survey in 1999-2002 had measurable evidence of chlordane exposure. “This is not cause for alarm,” added Sandler “since there is no evidence of health effects at such very low levels of exposure.”
Overall, pesticide applicators in the highest category of lifetime days of use of any pesticide had a small increase in risk for diabetes (17 percent) compared with those in the lowest pesticide use category (0-64 lifetime days). New cases of diabetes were reported by 3.4 percent of those in the lowest pesticide use category compared with 4.6 percent of those in the highest category. Risks were greater when users of specific pesticides were compared with applicators who never applied that chemical. For example, the strongest relationship was found for a chemical called trichlorfon, with an 85 percent increase in risk for frequent and infrequent users and nearly a 250 percent increase for those who used it more than 10 times. In this group, 8.5 percent reported a new diagnosis of diabetes compared with 3.4 percent of those who never used this chemical. Trichlorfon is an organophosphate insecticide classified as a general-use pesticide that is moderately toxic. Previously used to control cockroaches, crickets, bedbugs, fleas, flies and ticks, it is currently used mostly in turf applications, such as maintaining golf courses.