Comment on "Rheumatoid Arthritis in Agricultural Health Study Spouses: Associations with Pesticides and Other Farm Exposures"

We read the paper by Parks et al. with interest, particularly the increased risk of rheumatoid arthritis (RA) reported for maneb and mancozeb pesticide use (odds ratio [OR] = 3.3; 95% confidence interval [CI]: 1.5, 7.1). We suggest that these findings are explained by heavy metal exposure.