Long-term exposure to pesticides may raise a person's risk of developing diabetes, suggests a new study.
The study led by scientists from the NIH's National Institute of Environmental Health Sciences (NIEHS) and the National Cancer Institute (NCI) has found that licensed pesticide applicators who used chlorinated pesticides on more than 100 days in their lifetime were at greater risk of diabetes.
The association between specific pesticides and incidence of diabetes ranged from a 20 percent to a 200 percent increase in risk,
The researchers found that, 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 were diagnosed with diabetes compared with 3.4 percent of those who never used this chemical.
"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 added.
For the study, the researchers analyzed data from more than 30,000 licensed pesticide applicators participating in the Agricultural Health Study.
They later compared the pesticide use and other potential risk factors reported by the 1,171 applicators who developed diabetes since enrolling in the study to those who did not develop diabetes.
The team seven specific pesticides, aldrin, chlordane, heptachlor, dichlorvos, trichlorfon, alachlor and cynazine, that increased the likelihood of diabetes among study participants who had ever been exposed to any of these pesticides, and an even greater risk as cumulative days of lifetime exposure increased.