Pharmacokinetics of bisphenol A in humans following a single oral administration

Background: Human exposures to bisphenol A (BPA) are widespread. The current study addresses uncertainties regarding human pharmacokinetics of BPA. Objective: To reduce uncertainties about the metabolism and excretion of BPA in humans following oral administration. Methods: We exposed six men and eight women to 100 mu g/kg bw of deuterated BPA (d6-BPA) by oral administration and conducted blood and urine analysis over a three day period. The use of d6-BPA allowed administered d6-BPA to be distinguished from background native (unlabeled) BPA. We calculated the rate of oral absorption, serum elimination, half-life, area under the curve (AUC), urinary excretion, and metabolism to glucuronide and sulfate conjugates. Results: Mean serum total (unconjugated and conjugated) d6-BPA C-max of 1711 nM (390 ng/ml) was observed at T-max of 1.1 +/- 0.50 h. Unconjugated d6-BPA appeared in serum within 5-20 min of dosing with a mean C-max of 6.5 nM (1.5 ng/ml) observed at T-max of 1.3 +/- 0.52 h. Detectable blood levels of unconjugated or total d6-BPA were observed at 48 h in some subjects at concentrations near the LOD (0.001-0.002 ng/ml). The half-times for terminal elimination of total d6-BPA and unconjugated d6-BPA were 6.4 +/- 2.0 hand 6.2 +/- 2.6 h, respectively. Recovery of total administered d6-BPA in urine was 84-109%. Most subjects (10 of 14) excreted >90% as metabolites within 24 h. Conclusions: Using more sensitive methods, our study expands the findings of other human oral pharmacokinetic studies. Conjugation reactions are rapid and nearly complete with unconjugated BPA comprising less than 1% of the total d6-BPA in blood at all times. Elimination of conjugates into urine largely occurs within 24 h. Published by Elsevier Ltd