ISEE/ISEA 2006 Conference Abstracts Supplement: Session Abstracts: Abstracts
Among men heavily exposed to polychlorinated biphenyls (PCBs) and polychlorinated dibenzofurans (PCDFs), increased percent of oligospermia, reduced sperm capability of penetrating oocytes, and reduced percent of male offspring were reported by our study group. The mechanism of such effects is unknown. We test the hypothesis that effects on gender ratio and sperm functioning is related to sperm chromosomal aneuploidy.
During 1978 to 1979, over 2000 Taiwanese ingested rice oil contaminated with PCBs and its pyrolytic product, mainly PCDFs. This episode was referred to as “Yucheng” (“oil-disease” in Chinese) exposure. In 1999 to 2000, exposed men and their controls 37 to 50 years of age were recruited for physical examination followed by semen analysis. Semen samples were studied for chromosomal aneuploidy by fluorescent in situ hybridization with an established procedure in our laboratory. Hybridization procedures were done using centromere-specific probes directly labeled by fluorescence dyes (Vysis, Downers Grove, IL), including CEP X (SpectrumAqua), CEP Y (SpectrumOrange), and CEP 8 (SpectrumGreen). Each cell was scored for the number of fluorescent spots.
A total of 50 men exposed to PCBs/PCDFs and 34 unexposed matched controls volunteered to participate in the study. The age, body height and weight, percent of smokers, and period of abstinence from ejaculation were not different between exposed and control men. Percents of sperm with normal numbers of chromosomes X,Y, and 8 were not different between the 2 groups. Percents of sperm with aneuploidy of sex chromosomes or chromosome 8, and those with diploidy, were not different between Yucheng and control men. Ratios of normal X/normal Y sperm were not different between the exposed and control group. However, among Yucheng men, 4 (8%) had normal X/normal Y sperm ratio of >1.4; and among controls, none had such elevated X/Y ratio (not statistically significant by Fisher's exact test).
Discussion and Conclusions:
Chromosomal aneuploidy, diploidy, and X/Y sperm ratio were not increased in men highly exposed to PCBs/PCDFs despite reduced sperm capability of oocyte penetration, mildly increased abnormal morphology, and changed gender ratio in exposed men. The mechanisms of the latter remained to be determined.