A Mailed-questionnaire Survey of Ex-workers: A Tool to Evaluate the Healthy-worker Effect in Cross-sectional Studies

In order to evaluate a possible healthy-worker effect in a cross-sectional study in a viscose rayon plant, a survey of ex-workers was conducted. From the personnel records of this factory, 475 male, Caucasian, Dutch-speaking, carbon disulfide (CS&inf2;)-exposed workers who had been employed ten years prior to the cross-sectional study were selected for study. Of these, 142 were still employed in the same plant, and 64 were deceased. Retrieval of the causes of death proved impossible. A questionnaire was mailed to the remaining 269 men, of whom 149 completed and returned it. Eighty-nine subjects reported having left the plant for health reasons. Among the health reasons specified, eye-irritation complaints were most often mentioned (53.7%), followed by gastrointestinal complaints (32.8%), complaints concerning the central nervous system (19.4%) and the peripheral nerves (11.9%), heart or lung problems (14.9%), and problems affecting the skin (9.0%). The average duration of employment decreased significantly with the intensity of the exposure to CS&inf2;. The results suggest that the findings of a cross-sectional study of current workers in the same viscose rayon plant may represent underestimates of some conditions, in particular the acute eye-irritation complaints. Other complaints with high prevalences in the cross-sectional study, such as complaints consistent with polyneuropathy, seemed less, while others, such as impotence, seemed not at all, subject to underestimation.