The influence of perinatal and current dioxin and PCB exposure on reproductive parameters (sex-ratio, menstrual cycle characteristics, endometriosis, semen quality, and prematurity): a review

Polychlorinated biphenyls (PCBs) and dioxins (PCDDs/Fs) are well-known endocrine disrupters. This paper strives to elucidate the data on reproductive consequences of perinatal dioxin and PCB exposure in men and women. We focused on the following end-points: sex-ratio, endometriosis, menstrual cycle characteristics, sperm quality, and prematurity. We summarize 46 papers and compare their results including effects seen after exposure to background concentrations. Seven of twelve studies showed a decrease in sex-ratio after parental dioxin or PCB exposure. In three of the seven studies, effects were seen after paternal exposure and in three after maternal exposure. In eight of the nine studies on menstrual cycle characteristics, abnormalities were associated with PCB or dioxin exposure, however the results differed. In three studies PCB and TCDD were associated with longer menstrual cycles, while three studies indicated that an increase in PCB/PCDF exposure was associated with shorter cycles. Five studies showed effects on menstrual bleeding with higher PCB or dioxin exposure. A higher rate of irregular menstrual cycles in exposed women was seen in four studies. The conflicting outcomes probably result from variability in study design, timing of exposure and endocrine disrupting properties of the measured congeners. Nine of sixteen studies detected higher PCB or dioxin exposure in women with endometriosis. However, the manner of diagnosing endometriosis and the character of the studies varied from prospective to retrospective. Five of eight studies focusing on sperm quality showed that men, with higher serum concentrations of PCBs and/or PCB congeners and/or PCDFs, had reduced sperm quality, including increased abnormal morphology and reduced motility. The exposure timeframe seemed important here. There are two studies addressing preterm birth in relation to PCBs, one mentioned a shortening of three days of gestational age, two other studies did not find a relation. Recently one study related a shorter gestational age of half a week with overall dioxin activity measured with the CALUX method in cord blood, particularly in boys. In conclusion, exposure to PCBs and dioxins has a negative effect on the reproductive systems of human populations. Although some speculations have been made, the exact mechanism of these effects and the interactions of these compounds with other endocrine disruptors are not yet known. Age at exposure and congener specific properties are probably crucial in interpreting the observed results