Detection of low level benzene exposure in supermarket wrappers by urinarymuconic acid

Women who use the 'hot wire' and 'cool rod' machines to wrap meat in superm arkets are potentially exposed to law levels of benzene and polycyclic arom atic hydrocarbons present in fumes emitted during the thermal decomposition of the plastic used to wrap meat. In order to evaluate whether the benzene metabolite trans, trans-muconic acid (MA) can be used to monitor these low levels, we collected urine samples from supermarket workers, and assayed t he urine for MA. Geometric mean after-shift MA levels were highest for subj ects who used the 'hot wire' machine, i.e. > 300 ng mg(-1) creatinine (Cr). The corresponding levels for subjects who used the 'cool rod' machine were similar to those for subjects who did not use either type of machine, and were much lower These results indicate that urinary muconic acid has some p otential for use in monitoring benzene exposures of less than 1 part per mi llion (ppm). The study detected very high background MA levels (exceeding 2 000 ng mg(-1) Cr) in some subjects, suggesting that individuals in thr gene ral population without occupational exposure to benzene may have urinary MA levels equivalent to exposure to up to 2 ppm benzene in ambient air. Howev er, since non-benzene sources of the metabolite cannot be completely ruled out as partially responsible for these high levels, the public health signi ficance of this finding is not known at the moment.