Background
Depression in women is a public health   problem. Studies have reported positive associations between pesticides and   depression, but few studies were prospective or presented results for women   separately.
  Objectives
We evaluated associations between pesticide   exposure and incident depression among farmers' wives in the Agricultural Health   Study, a prospective cohort study in Iowa and North   Carolina.
  Methods
We used data on 16,893 wives who did not report   physician-diagnosed depression at enrollment (19931997) and who completed a   follow-up telephone interview (20052010). Among these wives, 1054 reported   physician diagnoses of depression at follow-up. We collected information on   potential confounders and on ever use of any pesticide, 11 functional and   chemical classes of pesticides, and 50 specific pesticides by wives and their   husbands via self-administered questionnaires at enrollment. We used inverse   probability weighting to adjust for potential confounders and to account for   possible selection bias induced by the death or loss of 10,639 wives during   follow-up. We used log-binomial regression models to estimate risk ratios and   95% confidence intervals.
  Results
After weighting for age at enrollment, state of   residence, education level, diabetes diagnosis, and drop out, wives' incident   depression was positively associated with diagnosed pesticide poisoning, but was   not associated with ever using any pesticide. Use of individual pesticides or   functional or chemical classes of pesticides was generally not associated with   wives' depression. Among wives who never used pesticides, husbands' ever use of   individual pesticides or functional or chemical classes of pesticides was   generally not associated with wives' incident   depression.
  Conclusions
Our study adds further evidence that high   level pesticide exposure, such as pesticide poisoning, is associated with   increased risk of depression and sets a lower bound on the level of exposure   related to depression, thereby providing reassurance that the moderate levels of   pesticide exposure experienced by farmers' wives likely do not increase   risk.
  Abbreviations
2,4-D, 2-(2,4-dichlorophenoxy)acetic   acid; 
2,4,5-T, (2,4,5-trichlorophenoxy)acetic acid; 
2,4,5-TP,   (RS)2-(2,4,5-trichlorophenoxy)propanonic acid; 
CI, Confidence interval;   
DDT, 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane; 
EPTC, S-ethyl   dipropyl(thiocarbamate); 
IQR, Interquartile range; 
NIEHS, National   Institute of Environmental Health Sciences; 
RR, Risk   ratio