Interaction Between Organophosphate Exposure and Serum PON1 Activity on Hypophysary and Male Sexual Hormones in Mexican Greenhouse Workers

Abstract

ISEE-0483 Background and Objective: Previous studies have found that organophosphate (OP) may act as endocrine disruptors. Paraoxonase1 (PON1) hydrolyzes the active metabolites of OP insecticides. People with a low PON1 activity have demonstrated an increased susceptibility to OP. The objective of this study was to evaluate the effect of interaction between OP exposure and serum PON1 activity on male hormone profile. Methods: A longitudinal study was conducted from July 2004–May 2005. A total of 137 men (18–52 years old) agreed to participate during the rainy season and 85 of them accepted again during the dry season. A general questionnaire, urine and blood samples were taken a day after pesticide application. Urine dialkylphosphates (DAP) were analyzed by gas chromatography. Serum samples were analyzed for FSH, LH, testosterone, estradiol, inhibin B and prolactin by immunoassay. Serum PON1 activity towards phenylacetate, paraoxon and diazoxon were determined as described by Richter and Furlong 1999, and serum p,p‘-DDE levels by gas chromatography. Molar quantities (mmol/L) of dimethyl DAP and diethyl DAP were calculated. The interaction effect between DAP levels and serum PON1 activity on serum hormones levels was evaluated using Generalized Estimated Equation models adjusted by potential confounders including serum p,p’-DDE. Results: A significant interaction (P = 0.05) was found between diazoxonase activity and SDAP on inhibin B levels. We observed a decrease in the percentage of variation of inhibin B for each increment in one unit of the logarithm concentration of åDAP together with diazoxonase activity increase (last quintile:-14.7 vs first quintile:-6.4%). The effect of interaction between dimethyl DAP and paraoxonase activity on testosterone was near to statistical significance (P = 0.06). No significant interaction was observed between serum PON1 activity an DAP levels on the other hormones. Conclusion: We found an effect of interaction between OP exposure and PON1 activity on serum inhibin B and testoterone levels.