Sperm aneuploidy among Chinese pesticide factory workers: Scoring by the FISH method

Background: A study of the prevalence of sperm aneuploidy among pesticide factory workers was conducted in Anhui, China. Methods: We recruited 75 men: 32 subjects from a large pesticide-manufacturing plant and 43 subjects from a nearby textile factory free of pesticide exposure. Each subject met the following criteria: age of 20-40 years; continuous work in the plant for 3 months prior to the study, no congenital anomalies or acquired disease of the external genitalia and no history of recent febrile illness or mumps. Within one hour after collection firm each subject, semen was evaluated in terms of several parameters and smear slides were prepared. Results: Exposure assessment revealed that workers in the pesticide plant were exposed to ethyl parathion or methamidophos, each of which is a potent organophosphate pesticide, at a median level of 0.02 mg/m3 (8-hour time weighted average as measured by personal pump) while workers in the control plant had no such occupational exposure. Twenty-nine semen slides (13 from the exposed group and 16 from the unexposed group) were randomly chosen for aneuploidy scoring by the three-color fluorescence in situ hybridisation (FISH) method with scorers being unaware of exposure status. Median semen parameters were as follows for exposed (and unexposed) men: abstinence period, 3 days (4 days): sperm concentration, 52.8 x 106/ml (53.1 x 106/ml), proportion of sperm with normal motility 50.5% (61.3%); and proportion of sperm with normal morphology, 59% (61.5%). The specific chromosome abnormalities of interest were disomy for chromosome 18 and the three different types of sex chromosome disomy (i.e. XX, XY, YY disomy). The crude proportion of all aneuploidy combined was 0.30% and 0.19% for sperm from exposed and unexposed men, respectively. Poisson regression with overdispersion adjustment yielded significantly different crude risks of alleuploidy - 3.03 and 1.94 per 1,000 sperm from exposed and unexposed men, respectively - giving a rate ratio of 1.56 (95% CI, 1.06-2.31). The regression coefficients remained statistically significant after adjustment for intertechnician variability giving a rate ratio of 1.51 (95% CI, 1.04- 2.20). Conclusions: We conclude that occupational exposure to organophosphate pesticides moderately increases the prevalence of sperm aneuploidy