A Rapid Assay for Urinary Metabolites of Benzo[a]pyrene (B[a]P)

Abstract

The so-called “reverse metabolism” technique for analysis of polycyclic aromatic hydrocarbon (PAH) metabolites through HI reduction to parent PAH fails for B[a]P. Most of the urinary metabolites of B[a]P are mercapturates. HCl hydrolysis of these similar cysteinyl conjugates derived from 9,10-epoxyphenanthrene yields the parent hydrocarbon. For the glutathione conjugates of B[a]P-7,8,9,10-tetrahydro-7,8-dihydroxy-9,10-epoxide, HCl hydrolysis appears to give the tetraol. Thus, HCl hydrolysis of mercapturates and analysis of the corresponding PAH and their hydroxylated derivatives is a potential pathway to assess human exposure to PAH, such as B[a]P, in which mercapturates are dominant conjugates. This is in contrast to selected PAH such as pyrene where sulfates, glucuronides and free phenols dominate.

Key Words:

• B[a]P
• hydrolysis
• human exposure
• urinary metabolites
• mercapturates
• B[a]P-7,8,9,10-tetrahydrotetraol