Biological monitoring of occupational exposure to polycyclic aromatic hydrocarbons (PAH) by determination of monohydroxylated metabolites of phenanthrene and pyrene in urine

Objectives The aim of our study was to assess individual polycyclic aromatic hydrocarbon (PAH) exposure of workers coming from three different industrial branches by several parameters of external and internal exposure. By analysing the relationships between those markers the suitability of individual parameters [e.g. monohydroxylated phenanthrene (Phe) metabolites] for exposure surveillance should be evaluated. Methods The total study population consisted of 255 male workers (age: 19-62, mean: 39.61 years), who were employed in coke production (n = 40), production of graphite electrodes and special carbon products (92), or production of refractory materials (123), respectively. For each worker external PAH exposure was determined by personal air sampling of 16 PAH, including Phe, pyrene (Pyr) and benzo[a]pyrene (BaP). For determination of internal PAH exposure the excretion of the PAH metabolites 1-, 2 + 9-, 3-, 4-hydroxyphenanthrene and 1-hydroxypyrene was measured in post-shift urine samples of all workers. Results In the total study population median total PAH exposure and exposure to BaP were 30.62 and 0.27 mu g/m(3), respectively. A calculation of PAH profiles resulted in substantial branch-related variations with Phe being a major component. Considering all branches the median excretions of 1-hydroxypyrene and hydroxyphenanthrenes (sum) were 6.68 and 11.22 mu g/g creatinine. A correlation analysis yielded a good correlation between total ambient PAH exposure and excretion of hydroxyphenanthrenes in urine (r = 0.662; P < 0.01), but no significant correlation between Phe metabolites and the carcinogenic BaP. For 1-hydroxypyrene and BaP a weak but significant association was found (r = 0.235; P < 0.01). Conclusions Considering the results of the correlation analysis hydroxyphenanthrenes in urine should reflect an uptake of lowly condensed volatile PAH rather than an incorporation of highly condensed PAH like BaP which should be reflected better by 1-hydroxypyrene. Therefore, the determination of hydroxyphenanthrenes in addition to the well-established marker 1-hydroxypyrene could offer some further information about the exposure situation at a particular work place.