Urinary 1-naphthol excretion in the assessment of exposure to creosote in an impregnation facility

Objectives This study explored the possibility of using urinary I-naphthol excretion as a marker of complex exposure among workers handling creosote. Methods Urine specimens of 6 workers from a creosote impregnation plant, where railroad ties were impregnated with coal tar creosote, were collected during 1 workweek, and the concentration of I-naphthol was determined. l-Naphthol in spot urine samples of 5 occupationally nonexposed male smokers was used as the background reference. Concurrently, naphthalene and 10 different polycyclic aromatic hydrocarbons (PAH) were determined in personal air samples. Results The mean airborne exposure of the workers was 1.5 mg/m(3) for vaporous naphthalene, 5.9 mg/m(3) for particulate PAH and 1.4 mu g/m(3) for PAH with 4-6 aromatic rings. The mean urinary concentration of I-naphthol at the end of the workshift was 20.5 (range 3.5-62.1) mu mol/l, whereas the referents' urinary concentration was below the detection limit (0.07 mu mol/l). Airborne naphthalene correlated fairly well with l-naphthol when measured at the end of the shift (r = 0.745). Conclusions This method of analysis for 1-naphthol is sufficiently sensitive for measuring low occupational exposures to naphthalene. Low background exposures are, however: unlikely to result in detectable urinary levels of I-naphthol. Since naphthalene is the most abundant compound in creosote vapor, urinary I-naphthol determination serves well as a biological marker of exposure to vaporous creosote. Urinary l-naphthol alone is not, however, a suitable marker for inhalatory or cutaneous exposure to PAH originating from creosote.