Kinetics of elimination of urinary metabolites of acrylamide in humans.

Acrylamide (AM), used in the manufacture of polyacrylamide and grouting agents, is produced during the cooking of foods. Workplace exposure to AM can occur through the dermal and inhalation routes. The objective of this study was to define the kinetics of elimination of AM and its metabolites following oral and dermal administration. This is the second part of a study in which metabolites and hemoglobin adducts of AM were determined in people (Fennell et al., 2005, Toxicol. Sci. 85, 447-459). (1,2,3-(13)C(3))AM was administered in an aqueous solution orally (single dose of 0.5, 1.0, or 3.0 mg/kg) or dermally (three daily doses of 3.0 mg/kg) to sterile male volunteers. Urine samples were collected at 0-2, 2-4, 4-8, 8-16, and 16-24 h following administration orally, or at 0-2, 2-4, 4-8, 8-16, and 16-24 h following each of three daily dermal doses. (13)C(3)-AM and its metabolites in urine, (13)C(3)-glycidamide, (13)C(3)-N-acetyl-S-(3-amino-3-oxopropyl)cysteine and its S-oxide, and (13)C(3)-N-acetyl-S-(3-amino-2-hydroxy-3-oxopropyl)cysteine, were quantitated using liquid chromatography-tandem mass spectrometry. The recovered urinary metabolites accounted for 45.6, 49.9, and 39.9% of a 0.5, 1.0, and 3.0 mg/kg oral dose (0-24 h), respectively, and for 4.5% of the dose after 3 mg/kg was administered daily for 3 days dermally (0-4 days). These results indicate that after oral administration AM is rapidly absorbed and eliminated. The half-life estimated for elimination of AM in urine was 3.1-3.5 h. After dermal administration, AM uptake is slow. This study indicated that skin provides a barrier that slows the absorption of AM, and results in limited systemic availability following dermal exposure to AM.