A Study for the Proper Application of Urinary Naphthols, New Biomarkers for Airborne Polycyclic Aromatic Hydrocarbons

Abstract

Urinary naphthols, 1- and 2-naphthol, recently have been suggested as route-specific biomarkers for exposure to airborne polycyclic aromatic hydrocarbons. For the proper application of urinary naphthols as biomarkers, we studied effects of lifestyle on urinary naphthols levels in 119 Japanese male workers. After improving the detection limit of urinary naphthols up to 0.27 microg/L by high-resolution capillary gas chromatography/mass spectrometry/selected ion monitoring, urinary naphthols were detectable in approximately 90% of the subjects. Among detectable samples, the geometrical mean (GM) of urinary 1-naphthol concentration was 5.13 microg/L (geometrical standard deviation, GSD, 4.90), while the GM of urinary 2-naphthol concentration was 3.16 microg/L (GSD, 5.61). We observed that urinary 1- and 2-naphthol level were three- and sevenfold higher, respectively, among smokers than among nonsmokers (p < 0.01). The ratios of urinary 2-naphthol to 1-naphthol were significantly higher among smokers than nonsmokers (p < 0.05). The number of cigarettes smoked and urinary cotinine levels were also positively related to the concentration of urinary naphthols (p < 0.01), while other lifestyle factors, i.e., age and consumption of alcohol, greasy or salty food, sweets, fruits, vegetables, meat, or fish, were not. We also studied whether genetic polymorphisms of enzymes, which were involved in naphthalene metabolism, affected urinary naphthols levels. The cytochrome P450 (CYP) 1A1 exon 7 genetic polymorphism was not related to urinary naphthol levels. Among smokers, the subjects with c1/c2 or c2/c2 type of CYP2E1, which was determined by CYP2E1 RsaI polymorphism in 5'-flaking region, showed higher concentrations of urinary 2-naphthol than the subjects with c1/c1 type regardless of creatinine-correction (p < 0.05) and the subjects with glutathione S-transferase (GST) M1 deficient type showed higher concentrations of both urinary 1- and 2-naphthol than those with GSTM1 normal type but only without creatinine-correction (p < 0.05). Thus, when urinary naphthols are used as biomarkers, smoking and the genetic polymorphisms of CYP2E1 and GSTM1 should be considered.

Sources of polycyclic aromatic hydrocarbon exposure in non‐occupationally exposed Koreans

“…Polycyclic aromatic hydrocarbons (PAHs), which are environmental carcinogens formed by the incomplete combustion of organic material, have been a major focus of research [Yang et al, 1999]. Humans may be exposed to PAHs through the air, soil, food, their occupation, and their lifestyle [Jongeneelen, 1994].…”

“…These types of studies are complicated by the varying bioavailability of PAHs from different exposure pathways (e.g., via inhalation, food consumption, skin contact), as well as individual differences in susceptibility to PAH exposure. Recently, genetic differences in the enzymes important for the metabolism of PAHs have been evaluated as susceptibility biomarkers for PAH biomonitoring [Yang et al, 1999;Nerurkar et al, 2000]. However, it is difficult to observe the effects of genetic differences on biological monitoring without considering all the major exposure routes of PAHs.…”

Urinary 1‐Hydroxypyrene Level Relative to Vehicle Exhaust Exposure Mediated by Metabolic Enzyme Polymorphisms

“…Cytochromes p-450 (CYP) is a family of biotransformation phase I enzymes which catalyze the metabolism of xenobiotics. CYP1A1 catalyzes the oxidation of PAH and the formation of their active oxygen metabolites [16][17][18] . Glutathione S-transferases (GSTs) are biotransformation phase II enzymes, which have been reported to catalyze the conjugation of PAH diol epoxide metabolites with reduced glutathione.…”

Occupational Exposure to Aromatic Hydrocarbons at a Coke Plant: Part II. Exposure Assessment of Volatile Organic Compounds

“…Naphthalene tends to be the predominant airborne compound in the processing and handling of coal tar products 1,16) , in iron foundry 29) and in creosote impregnation plants 30,31) Naphthalene is metabolized almost exclusively to 1-naphthol and 2-naphthol 16) . Detection of naphthols in the urine is the most widely used indicator of naphthalene exposure 32,33) As seen in Table 2, concentrations of naphthol isomers are higher in the urine of workers engaged in the naphthalene oil distillation than in the tar distillation departments, but are not statistically significant. Differences between the concentrations of 1-naphthol and 2-naphthol detected in the urine of exposed and nonexposed subjects are statistically significant.…”

“…Differences between the concentrations of 1-naphthol and 2-naphthol detected in the urine of exposed and nonexposed subjects are statistically significant. Earlier investigations were able to determine simultaneously the presence of 1-naphthol and 2-naphthol in the urine of workers employed at the naphthalene oil distillation process in a coke plant 32) . It was found that the concentrations of the naphthols were significantly higher than in the present results.…”