Validity study of self-reported pesticide exposure among orchardists

Self-reported work histories are often the only means of estimating occupat ional exposures in epidemiologic research. The objective of this study was to examine the accuracy of recall of historical pesticide use among orchard ists. All 185 orchardists in this study had participated previously in a co hort study of men occupationally exposed to pesticides. In that study (1972 to 1976), subjects were interviewed annually and asked to list pesticides used since the last interview. In 1997, 265 of the 440 presumed-living orch ardists from the original cohort were successfully recontacted and asked to complete a detailed questionnaire concerning their lifetime use of pestici des; 185 (69.8% of farmers successfully contacted) agreed. Considering the 1972-1976 data as the standard, sensitivity and specificity of recall were calculated for certain pesticides and pesticide categories. Sensitivity of recall was good to excellent (0.6-0.9) fur the broad categories of insectic ides, herbicides, and fungicides, for heavily used chemical classes, such a s organophosphates and organochlorines, and for commonly used pesticides; i t was lower and more variable (0.1-0.6) for specific pesticides. Recall spe cificity was greatest (0.7-0.9) for the least used pesticides and chemical classes, such as dithiocarbamates and manganese-containing pesticides, and was generally modest for the rest (0.5-0.6). There was no evidence of selec tion bias between study participants and nonparticipants. In conclusion, re call accuracy was good for commonly used pesticides and pesticide categorie s. This level of recall accuracy is probably adequate for epidemiologic ana lyses of broad categories of pesticides, but is a limitation for detecting more specific associations.