To assess the association between exposure to organophosphates and thyroid function in greenhouse workers of Morelos, Mexico.
Material and Methods:
Following the day the pesticides were sprayed, serum and urine samples from 104 male greenhouse workers (15 organic farmers and 89 flower-growing workers), during July to October 2004, were collected. Urine samples were analyzed for dialquilphosphates (DAP), dimethylphosphate (DMP), diethylthiophosphate (DEP), dimethylthiophosphate (DMTP), dimethyldithiophosphate DMDTP, diethylthiophosphate (DETP), diethyldithiophosphate (DEDTP) by gas chromatography. Serum samples were analyzed for free T4 and total T3 by immunofluorimetry and thyroid stimulating hormone (TSH) by immunoassays. A general questionnaire was filled out to obtain information about socioeconomic characteristics, pathologic antecedents, occupational history, and exposure to specific pesticides.
The most frequent metabolite found in urine samples were DMP and DMTP, 81% and 54%, respectively. Multiple linear regression models showed a positive significant association between serum levels of TSH and urinary levels of DMP [[beta] 0.48; 95% CI (0.17–0.79)] and DAP totals (sum of 6 urinary metabolites) [[beta] 0.45; 95% CI (0.002-0.90)] and an inverse significant association with total T3 [[beta] −0.04; 95% CI (−0.07.17 to −0.01)] and [[beta] −0.04; 95% CI (−0.08 to 0.002)], respectively. The results showed a non-significant inverse relationship between free T4 and this organophosphate metabolites (DMP and DAP totals).
Occupational exposure to organophosphate in Mexican greenhouse workers could be associated with altered thyroid function.