There is novel evidence of associations between exposure to some pesticides and rheumatoid arthritis (RA) in male farmers, according to a recent study. Researchers investigated associations between RA and use of pesticides in the Agricultural Health Study. The sample was drawn from male pesticide applicators enrolled in 1993–1997 who provided questionnaire data at baseline and at least once during follow-up. Incident RA cases (n=220), confirmed by physicians or by self-reported use of disease-modifying antirheumatic drugs, were compared with non-cases (n=26,134) who did not report RA. Researchers evaluated the association of RA with the use of 46 pesticides and across 4 levels (never use and tertiles) of lifetime days of use for 16 pesticides with OR≥1.2 for ever use. They found:

• Incident RA was associated with ever use of fonofos, carbaryl, and chlorimuron ethyl compared with never use.
• Statistically significant exposure–response trends in association with RA were observed for lifetime days of use of atrazine and toxaphene.
• Exposure–response was nonlinear for fonofos and suggestive for carbaryl.