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Organochlorine Pesticides Exposure and Bladder Cancer: Evaluation from a Gene-Environment Perspective in a Hospital-Based Case-Control Study in the Canary Islands (Spain)

ABSTRACT The incidence of bladder cancer has increased significantly since the 1950s. Pesticide exposure has been linked with increasing bladder cancer incidence, although the evidence is inconclusive. However, most epidemiological studies did not evaluate the potential role played by the organochlorine pesticides, the most widely used pesticides in Western countries from the 1940s to the 1970s. Organochlorine pesticides were banned in the late 1970s because of their persistence in the environment and their carcinogenic and mutagenic effects. Organochlorine pesticides were employed in huge amounts in the Spanish archipelago of the Canary Islands; the authors, therefore, evaluated the role played by organochlorine pesticides exposure on bladder cancer. Serum levels of the most prevalent organochlorine pesticides used in the agriculture of these Islands (dichlorodiphenyltrichloroethane [p,p’-DDT], and its metabolites dichlorodiphenyldichloroethylene [p,p’-DDE] and dichlorodiphenyldichloroethane [p,p’-DDD], hexachlorobenzene, hexachlorocyclohexane isomers, aldrin, dieldrin, endrin, heptachlor, cis-chlordane, trans-chlordane, α- and β-endosulfan, endosulfan sulfate, methoxychlor, and mirex) were measured in 140 bladder cancer cases and 206 controls. GST-M1 and GST-T1 gene polymorphisms were genotyped by polymerase chain reaction (PCR)-based methods. These results showed that serum levels of organochlorine pesticides did not increase bladder cancer risk. On the contrary, total burden of hexachlorocyclohexanes was found to be negatively associated to bladder cancer (odds ratio [OR] = 0.929, 95% confidence interval [CI]: 0.865–0.997; P = .041). This effect disappeared when the distribution of the gluthathione S-transferase polymorphisms was introduced in the statistical model. These results indicate that organochlorine pesticides are not a risk factor for bladder cancer. However, these findings provide additional evidence of gene-environment interactions for organochlorine pesticides and bladder cancer and reinforce the relevance of genes encoding xenobiotic-metabolizing enzymes in bladder cancer.