Endocrine Abstracts

Background: Human toxicity of bisphenol-A (BPA), a weak estrogenic environmental endocrine disruptor widely used in plastics, babybottles, cans and dental sealants, is under investigation. Human pharmacokinetics involves a rapid inactivation by hepatic glucuronyl- or sulfoconjugation and renal clearance. Fetal or perinatal exposure in rodents is associated with programmed adult reproductive diseases. Human epidemiological studies remain scarce especially concerning testicular development.

Methods: Using a radioimmunoassay performed after extraction, validated by HPLC and mass spectrometry, active, unconjugated BPA (uBPA) cord blood (CB) levels were measured in 152 boys born after 34 weeks of amenorrhea with or without descended testes.

Results: Active uBPA was detectable in all CB samples with values in the control group (N=106) between 0.14 and 4.76 ng/ml, median: 0.9 ng/ml; mean±SD: 1.12 ng/ml±0.86 ng/ml. uBPA in controls correlated with CB inhibin B (P<0.01) and total testosterone (P<0.05) and maternal milk polychlorinated bisphenyl (PCB) 138 (P<0.03). uBPA did not correlate with clinical maternal or fetal parameters nor with other steroid or polypeptidic CB hormones assessed. uBPA levels were not significantly different in cryptorchid boys (N=46): 1.26±1.13 ng/ml (P=0.38).

Conclusions: uBPA was present in all cord blood samples assessed, illustrating placenta transfer and foetal exposure due to either placental hydrolysis of maternal conjugated BPA and/or immaturity of fetal detoxification capacity. uBPA correlation with testosterone CB levels could be in relation to androgen dependent regulation of glucuronyltransferase gene expression. Lack of difference of cord blood uBPA levels between control and cryptorchid groups in this prospective study, makes unlikely the participation of fetal exposure to uBPA in the physiopathology of undescended testes. However the observed uBPA concentrations (nM) similar to those able to induce relevant effects in vivo in rodents or in vitro in human cancer cell lines, invite to further assess epidemiological relationship between cord blood uBPA and other human reproductive or not reproductive diseases.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.