Metabolism of the endocrine disruptor BPA by Xenopus laevis tadpoles.

Metabolism of the plasticizer bisphenol A (BPA), a thyroid function disruptor, was investigated in Xenopus laevis tadpoles. Uptake and biotransformation of [(3)H]-BPA was followed over 72 h at 1 micromol/L and 10 micromol/L +/- triiodothyronine. A rapid decrease of radioactivity in media was observed after [(3)H]-BPA was added. [(3)H]-BPA uptake reached 25% after 24 h then ranged between 6% and 15%. Metabolic profiles of water samples at 24, 48, and 72 h as well as tadpole extracts (at 72 h) were obtained using radio-HPLC. Parent (unmodified) BPA was consistently found in water samples and within tadpoles. Six peaks corresponding to BPA metabolites were detected. Based on retention time comparison with standards isolated from rat and human material, the two main metabolites were identified as BPA-glucuronide and BPA-sulfate. Thus, Xenopus laevis provides a useful model for studying BPA effects in vertebrates, as the main BPA metabolites are similar to those produced in mammals.