Cord blood thyroid tests in boys born with and without cryptorchidism: correlations with birth parameters and in utero xenobiotics exposure.

BACKGROUND: In utero exposure to environmental chemicals can result in reproductive toxicity via endocrine disruption mechanisms. Whether some of those contaminants also have an impact on fetal thyroid function or pathways, and, thus, potentially on neuropsychological development, is still debated. METHODS: We used samples from a cord blood (CB) and milk bank, established for a research on cryptorchidism and xenobiotic exposure to compounds known for their anti-androgenic and/or estrogenic activity, to study CB thyroid tests and their correlation with CB and milk xenobiotics concentrations in boys born in Nice area. RESULTS: No difference was found in thyroid tests between 60 cryptorchid boys and 76 matched controls (median thyroid stimulating hormone 5.97 vs. 6.55 mUI/L, free thyroxine [fT4] 13.1 vs. 12.9 pmol/L, free triiodothyronine [fT3] 1.9 vs. 2.1 pmol/L), with no influence of season of birth, gestational age, maternal smoking, or mode of delivery (except for higher fT4 in control boys born vaginally). FT4 was correlated with fetal growth only in cryptorchid boys. Since we had previously shown differences between cryptorchid and controls exposure, we studied correlations of thyroid tests with xenobiotics in control boys only. All tested CB or maternal milk was contaminated by one or more selected xenobiotics, mainly polychlorinated biphenyls (PCBs), dichloro diphenyl dichloroethylène (DDE), dibutylphthalate, hexachlorobenzene, and bisphenol A. We found a significant negative correlation between fT4 and concentrations of PCB118, PC180, and DDE in milk (respectively r = -0.342, p < 0.03, r = -0.296, p = 0.031, r = -0.315, p = 0.016), persisting after adjustment for mode of delivery. There was a significant positive correlation of fT3 with milk concentrations of PCB138, PCB153, ΣPCB, and dibutylphthalate (respectively r = 0.31, p = 0.016, r = 0.28, p = 0.029; r = 0.34, p = 0.0079 and r = 0.272, p = 0.0295), with a trend for PCB180 (r = 0.259, p = 0.061). There was no correlation of thyroid stimulating hormone with any of the measured xenobiotics, except for a weak negative trend with CB bisphenol A (r = -0.25, p = 0.077). CONCLUSIONS: CB thyroid tests are within normal range in cryptorchid boys, similar to controls. Our data in controls suggest a possible weak correlation between in utero exposure to some xenobiotics (PCBs, DDE) and fT3 and fT4 CB concentrations, with usually negative correlations with fT4 and positive with fT3 concentrations, which we speculate could suggest an impact on deiodinases.

Exposure to selected endocrine disruptors and neonatal outcome of 86 healthy boys from Nice area (France).

In utero and lactational exposure to endocrine disruptors is thought to be potentially harmful on fetal and infant development. Data of exposure in France is scarce. This is a prospective study with (1) collection of 84 cord bloods (CB) and 69 milks from 86 mothers delivering healthy boys (gestational age >or= 34 weeks) at two maternity wards in Southern France, between 2002 and 2005 and (2) screening for 15 xenobiotics with anti-androgenic and/or estrogenic effects: DDE, 7 PCBs, dibutylphthalate and its metabolite mBP, HCB, lindane, linuron, procymidone and vinclozoline. Correlations were made with delivery and neonatal outcomes. All CB and milks were contaminated by one or more xenobiotics (mainly PCBs, DDE, HCB, and phthalates) with good correlation between CB and milk concentrations. Compared to other geographical areas, exposure was usually in the lower bracket. Milk [PCB180] was associated with lower birth weight. Infant head circumference correlated negatively with [HCB] and positively with [mBP] in CB. There was a similar but not significant trend for birth weight and length. [DDE] in milk was higher in older mothers and in women born in Africa. In utero and lactational exposure is ubiquitous in our area. Contamination of milk with HCB, mBP, and PCB 180 showed weak correlations with infant growth. This snapshot of exposure in an area with no major industry will serve for further monitoring.