The relative bioavailability and metabolism of bisphenol A in rats is dependent upon the route of administration

Bisphenol A (BPA) is used to produce polymers for food contact applications , thus there is potential for oral exposure of humans to trace amounts via the diet. BPA was weakly estrogenic in screening assays measuring uterine w eight/response, although much higher oral doses of BPA were required to eli cit a uterotropic response as compared to other routes of administration. T he objective of this study was to determine if a route dependency exists in the pharmacokinetics and metabolism of C-14-labeled BPA following single o ral (po), intraperitoneal (ip), or subcutaneous (sc) doses of either 10 or 100 mg/kg to Fischer 344 rats. Results indicated a marked route dependency in the pharmacokinetics of BPA, The relative bioavailability of BPA and pla sma radioactivity was markedly lower following oral administration as compa red to sc or ip administration. The major fraction of plasma radioactivity following oral dosing was the monoglucuronide conjugate of BPA (68-100% of plasma radioactivity). BPA was the major component in plasma at Cmax follow ing sc or ip administration exceeded only by BPA-monoglucuronide in females dosed ip, Up to four additional unidentified metabolites were present only in the plasma of animals dosed ip or sc. One of these, found only followin g ip administration, was tentatively identified as the monosulfate conjugat e of BPA, The monoglucuronide conjugate was the major urinary metabolite; u nchanged BPA was the principal component excreted in feces. These results d emonstrated a route dependency of BPA bioavailability in rats, with oral ad ministration resulting in the lowest bioavailability, and offer an explanat ion for the apparent route differences in estrogenic potency observed for B PA.