IARC MONOGRAPHS ON THE EVALUATION OF CARCINOGENIC ...

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IARC MONOGRAPHS VOLUME 82
and three glutathione conjugates. These metabolites were also identified in animal
studies, as discussed in Section 4.1.2.
Urinary metabolites of naphthalene are useful biomarkers of exposure. Seventy-five
workers exposed to naphthalene while distilling naphthalene oil excreted 7.48 mg/L
(4.35 mg/g creatinine) 1-naphthol (geometric mean values) at the end of the workshift.
For 24 non-occupationally exposed individuals, the mean urinary concentration of
1-naphthol was 0.13 mg/L (Bieniek, 1994). 1-Naphthol, 2-naphthol and 1,4-naphthoquinone
(14, see Figure 1) were identified in the urine of 69 coke-plant workers exposed
to a geometric mean air concentration of naphthalene of 0.77 mg/m 3 during tar distillation.
The end-of-workshift urinary concentrations of 1-naphthol and 2-naphthol were
693 and 264 μmol/mol creatinine. The correlation coefficients between the urinary excretion
of naphthols and exposure to naphthalene were 0.64–0.75 for 1-naphthol and
0.70–0.82 for 2-naphthol. There was a linear relationship between the overall concentration
of naphthols in urine and the naphthalene concentration in air (Bieniek, 1997). In
a further study of a coke plant, Bieniek (1998) measured the concentrations of 1-naphthol
and 2-naphthol in urine from eight workers in coke batteries, 11 workers in the sorting
department and 29 workers in the distillation department. The mean urinary concentrations
of 1-naphthol and 2-naphthol were 294 and 89 μmol/mol creatinine for the
coke-battery workers, 345 and 184 μmol/mol creatinine for the sorters and 1100 and
630 μmol/mol creatinine for the distillation workers, respectively.
Andreoli et al. (1999) examined 15 urine samples from workers in a naphthaleneproducing
plant who were exposed to 0.1–0.7 mg/m 3 naphthalene. At the end of the
workshift, the median urinary concentrations of 2-naphthyl sulfate, 2-naphthyl glucuronide
and 1-naphthyl glucuronide were 0.030 (range, 0.014–0.121), 0.086 (range,
0.013–0.147) and 0.084 (range, 0.021–0.448) mg/L, respectively.
Since naphthalene is the most abundant component of creosote (Heikkilä et al.,
1987), urinary excretion of 1-naphthol was determined in three assembly workers
handling creosote-impregnated wood. The average airborne concentration of naphthalene
in the breathing zone was approximately 1 mg/m 3 . The average end-of-shift concentration
of 1-naphthol in urine changed from 254–722 (mean, 556) μmol/mol creatinine
on Monday to 1820–2190 (mean, 2060) μmol/mol creatinine on Wednesday and 870–
2330 (mean, 1370) μmol/mol creatinine on Friday. The same metabolite was measured
in the urine of six workers exposed to creosote in a plant impregnating railroad ties
(Heikkilä et al., 1997). As measured by use of personal air samplers, the mean airborne
concentration of naphthalene in the workers’ breathing zone was 1.5 (range,
0.37–4.2) mg/m 3 . The mean end-of-shift concentration of 1-naphthol was 20.5 (range,
3.5–62.1) μmol/L. There was a good correlation (r = 0.745) between concentrations of
airborne naphthalene and urinary 1-naphthol. No 1-naphthol was detected (limit of
detection < 0.07 μmol/L) in the urine of five non-exposed controls. Hill et al. (1995)
measured 1-naphthol and 2-naphthol in the urine of 1000 adults without occupational
exposure — a subset of the National Health and Nutrition Examination Survey III —
who may have been exposed to low levels of naphthalene or pesticides that would yield