Occupational exposure to pesticides and bile tract carcinoma in men: results from a European multicenter case-control study

OBJECTIVES: To estimate the associations between occupational exposure to pesticides and extrahepatic biliary tract carcinoma in men, a population-based case-control study was carried out. METHODS: Cases (n = 104), aged 35-70, diagnosed in 1995-1997, were sampled by active reporting systems from hospitals. Controls (n = 1,401) were a random sample of the general male population. Information on occupation and confounding factors was obtained by questionnaires. Exposures were quantified with respect to time, application methods, and use of personal protective equipment. Intensity was evaluated by using a published algorithm which weighted the exposure assigned according to the use of personal protective equipment and mode of application. Logistic regression analyses were conducted adjusted for gallstones, age, and country. RESULTS: Being ever exposed to pesticides resulted in an odds ratio (OR) of 1.0 [95%-confidence interval (CI) 0.6-1.6]. A modestly elevated risk was found for backpack mounted sprayers OR = 1.4 [95% CI 0.7-2.6] and vine farmers OR = 2.5 [95% CI 0.9-7.2]. Using time periods and exposure frequency as intensity measure, no elevated risks were found. The only exception was year of maximum exposure which yielded an OR of 1.6 [95% CI 0.7-3.5]. However, no clear trend was observed in this analysis. CONCLUSIONS: This study does not rule out that pesticide exposure represents an occupational risk factor for extrahepatic biliary tract carcinoma, but no indication of a strong association was observed. Some modes of exposure were weakly, albeit not significantly associated with carcinoma risk. The observed estimates of effects may be influenced by a lack of precise exposure assessment. Different chemical compositions of pesticides were utilized during a long time span of pesticide exposure, and it should be considered that the exposure is assessed with substantial uncertainty that could non-differential and bias results toward the null.