Associations of Specific Pesticides and Incident Rheumatoid Arthritis Among Female Spouses in the Agricultural Health...

Growing evidence suggests farming and agricultural pesticide use may be associated with rheumatoid arthritis (RA), but few studies have examined specific pesticides and RA among women living on farms, who may personally use pesticides or may be indirectly exposed. We investigated pesticide use and RA risk among female spouses of licensed pesticide applicators in the Agricultural Health Study.

Participants were enrolled in 1993 to 1997 in North Carolina and Iowa (N = 32,126). Incident RA cases were identified in follow-up questionnaires (1999-2021) and confirmed by medical records, relevant medication use, or Medicare claims data (1999-2016) or identified from Medicare claims if lacking questionnaire data on RA. Noncases reported no RA and had no RA Medicare claims. Among those with complete covariate data (N = 410 cases and 21,850 noncases), we examined associations with pesticide classes and 32 specific pesticides (personal lifetime use reported at enrollment, updated in 1999-2003). We calculated odds ratios (ORs) and 95% confidence intervals (CIs), adjusting for age, state, education, smoking pack-years smoking, body mass index, and correlated pesticides (ρ > 0.35).

Incident RA was associated with use of organochlorine (DDT: OR 1.89, 95% CI 1.30-2.75; lindane: OR 1.97, 95% CI 1.12-3.47) and organophosphate insecticides (coumaphos: OR 2.32, 95% CI 1.29-4.19; malathion: OR 1.21, 95% CI 0.91-1.62), the carbamate insecticide carbofuran (OR 1.87, 95% CI 0.97-3.63), and permethrin and pyrethroid insecticides on crops (OR 1.56, 95% CI 0.92-2.64) and livestock (OR 1.69, 95% CI 1.07-2.68). RA was not associated with using herbicides, except for metribuzin (OR 1.88, 95% CI 0.94-3.79). The fungicides captan (OR 1.78, 95% CI 1.13-2.83) and metalaxyl (OR 2.49, 95% CI 1.41-4.40) were also associated with RA.

These findings indicate that persistent organochlorine insecticides and some pesticides also used in public health or residential settings may increase RA risk in women.