Percutaneous absorption and metabolism of [14C]-ethoxycoumarin in a pig ear skin model.

The biotransformation of chemicals by the skin can be a critical determinant of systemic exposure in humans following dermal absorption. Pig ear skin, which closely resembles human skin, is a candidate ex vivo alternative model for the investigation of xenobiotics penetration and metabolism. We developed an ex vivo pig ear skin model and explored its absorption, diffusion and metabolic capabilities using the model compound (14)C-ethoxycoumarin (7-EC).

Biotransformations of bisphenol A in a mammalian model: answers and new questions raised by low-dose metabolic fate studies in pregnant CD1 mice.

We investigated the metabolic fate of a low dose (25 micro g/kg) of bisphenol A [2,2-bis(4-hydroxy-phenyl)propane] (BPA) injected subcutaneously in CD1 pregnant mice using a tritium-labeled molecule. Analytic methods were developed to allow a radio-chromatographic profiling of BPA residues in excreta and tissues, as well as in mothers' reproductive tracts and fetuses, that contained more than 4% of the administered radioactivity. BPA was extensively metabolized by CD1 mice.

In vivo metabolic fate of the xeno-estrogen 4-n-nonylphenol in Wistar rats.

The distribution and the metabolic fate of 4-n-nonylphenol were investigated in male and female Wistar rats dosed orally with 1 microg/kg ("low-dose") or 10 mg/kg ("high-dose") labeled 4-n-nonylphenol. Following a 4-day metabolic balance study, neither the distribution pattern nor the residual levels of 4-n-nonylphenol were found to be different between groups, and no unexpected tissue-specific accumulation of 4-n-nonylphenol was detected. Most of the radioactivity was eliminated in urine, and consisted of hydrophilic metabolites very likely resulting from extensive beta-oxidation of the nonyl side chain and from the conjugation of the phenol to sulfate or to glucuronic acid.