Biological monitoring of low exposures to polycyclic aromatic hydrocarbons

Aim of the work was the assessment of low exposure to polycyclic aromatic hydrocarbons (PAHs) by biological monitoring. Italian asphalt workers (AW, n=100) and roadside construction workers (CW, n=47) were investigated by measurement of hydroxylated metabolites and unmetabolized PAHs in urine spot samples collected respectively after two days of vacation (baseline), before and at the end of the monitored workshift, in the second part of the workweek. Biomarkers were determined by HPLC-fluorimetry and GC-MS. Median airborne levels during the workshift of 15 PAHs (both vapour and particulate phases), from naphthalene to indeno(1,2,3-cd)pyrene, ranged from below 0.03 to 426 ng/m3. Median excretion values of 1-hydroxypyrene (OH-Py) in baseline, before- and end-shift samples were 1.04, 1.84 and 3.16 nmol/L for AW and 1.19, 1.39 and 1.73 nmol/L for CW; lower values were found in non-smokers compared to smokers. In all subjects a weak correlation between personal exposure to the sum of airborne 15 PAHs and OH-Py was observed. Urinary naphthalene, phenanthrene, pyrene and fluorene were detected in the majority of the samples in the range below 0.01 to 2.54 nmol/L. Significant differences in the levels of the unmetabolized compounds were found between AW and CW. Moreover in AW samples the urinary excretion of most analytes increased during the work shift. The results of this study show that AW experienced a moderate occupational exposure to airborne PAHs, resulting in a significant increase of urinary biomarkers during the workday and the workweek. Both hydroxylated metabolites and unmetabolized PAHs in urine may be suggested as biomarkers of low exposure to PAHs.