[Validation of a questionnaire for retrospectively measuring occupational pesticide exposure]

The aim of this study is to validate a questionnaire intended to assess retrospective occupational exposure to pesticides in a case control study of workers exposed to pesticides and congenital malformations.

Occupational data were gathered through personal interviews to 56 agricultural workers and this information was compared to: 1) personal interviews with the workers' foremen, 2) direct observation of working places and 3) another questionnaire self-administered previously by the workers as a part of the "Training Program for Pesticide Applicators".

Accuracy and reliability indices are high for variables such as the crops where the interviewees have been working, the time period of the treatments with pesticides and the use of personal protection during treatments (sensitivity ranges between 0.81 and 1 and Kappa index ranges between 0.65 and 0.80). However, for variables such as the duration of the treatments and the pesticides used, sensitivity values range between 0.32 and 0.50.

The results suggest that the questionnaire is a valid tool for measuring some items but in order to improve the quality of the exposure assessment the questionnaire was modified, including a question about size of treated areas (as a proxy variable for duration of treatments) and prompt lists were developed to make easier recall by the workers of specific pesticides used in treatments.