title: Naphthalene and its biomarkers as measures of occupational exposure to polycyclic aromatic hydrocarbons.
abstract: Polycyclic aromatic hydrocarbons (PAH) include compounds with two or more fused benzene rings, many of which are carcinogens. Industrial sources produce hundreds of PAH, notably in the coke- and aluminium-producing industries. Because PAH are distributed at varying levels between gaseous and particulate phases, exposure assessment has been problematic. Here, we recommend that occupational exposures to naphthalene be considered as a potential surrogate for occupational PAH exposure for three reasons. Naphthalene is usually the most abundant PAH in a given workplace; naphthalene is present almost entirely in the gaseous phase and is, therefore, easily measured; and naphthalene offers several useful biomarkers, including the urinary metabolites 1- and 2-hydroxynaphthalene. These biomarkers can be used to evaluate total-body exposure to PAH, in much the same way that 1-hydroxypyrene has been applied. Using data from published sources, we show that log-transformed airborne levels of naphthalene are highly correlated with those of total PAH (minus naphthalene) in several industries (creosote impregnation: Pearson r= 0.815, coke production: r= 0.917, iron foundry: r= 0.854, aluminium production: r= 0.933). Furthermore, the slopes of the log-log regressions are close to one indicating that naphthalene levels are proportional to those of total PAH in those industries. We also demonstrate that log-transformed urinary levels of the hydroxynaphthalenes are highly correlated with those of 1-hydroxypyrene among coke oven workers and controls (r= 0.857 and 0.876), again with slopes of log-log regressions close to one. These results support the conjecture that naphthalene is a useful metric for occupational PAH exposure. Since naphthalene has also been shown to be a respiratory carcinogen in several animal studies, it is also argued that naphthalene exposures should be monitored per se in industries with high levels of PAH.
authors.affiliation: Department of Environmental Sciences and Engineering, School of Public Health, CB# 7431, University of North Carolina, Chapel Hill, NC 27599-7431, USA. smr@unc.edu
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Rappaport
authors.forename: Suramya
authors.initials: S
authors.lastname: Waidyanatha
authors.forename: Berrin
authors.initials: B
authors.lastname: Serdar
mesh_terms: D000535:Aluminum; D000818:Animals; D015415:Biomarkers / Q000652:urine; D002273:Carcinogens / Q000633:toxicity; D003077:Coke; D006801:Humans; D007221:Industry; D009281:Naphthalenes / Q000032:analysis*; D009284:Naphthols / Q000032:analysis; D016273:Occupational Exposure / Q000032:analysis*; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis*; D011721:Pyrenes / Q000032:analysis; D013232:Steel
chemical_list: D015415:Biomarkers; D002273:Carcinogens; D003077:Coke; D009281:Naphthalenes; D009284:Naphthols; D011084:Polycyclic Aromatic Hydrocarbons; D011721:Pyrenes; D013232:Steel; D000535:Aluminum; C033146:1-hydroxypyrene