Urinary 1-hydroxypyrene as a biomarker of exposure to polycyclic aromatic hydrocarbons: biological monitoring strategies and methodology for determining biological exposure indices for various work environments

This article reviews the published studies on urinary 1-hydroxypyrene (1-OH P) as a biomarker of exposure to polycyclic aromatic hydrocarbons (PAHs) in work environments. Sampling and analysis strategies as well as a methodolo gy for determining biological exposure indices (BEIs) of 1-OHP in urine for different work environments are proposed for the biological monitoring of occupational exposure to PAHs. Owing to the kinetics of absorption of pyren e by different exposure routes and excretion of 1-OHP in urine, in general, 1-OHP urinary excretion levels increase during the course of a work day, r eaching maximum values 3-9 h after the end of work. When the contribution o f dermal exposure is important, post-shift 1-OHP excretion can however be l ower than pre-shift levels in the case where a worker has been exposed occu pationally to PAHs on the day prior to sampling. In addition, 1-OHP excreti on levels in either pre-shift, post-shift or evening samples increase durin g the course of a work-week, levelling off after three consecutive days of work. Consequently, ideally, for a first characterization of a work environ ment and for an indication of the major exposure route, considering a 5-day work-week (Monday to Friday), the best sampling strategy would be to colle ct all micturitions over 24 h starting on Monday morning. Alternatively, co llection of pre-shift, post-shift and evening urine samples on the first da y of the work-week and at the end of the work-week is recommended. For rout ine monitoring, pre-shift samples on Monday and postshift samples on Friday should be collected when pulmonary exposure is the main route of exposure. On the other hand, pre-shift samples on Monday and Friday should be collec ted when the contribution of skin uptake is important. The difference betwe en beginning and end of work-week excretion will give an indication of the average exposure over the work-week. Pre-shift samples on the first day of the work-week will indicate background values, and, hence, reflect general environment exposure and body burden of pyrene and/or its metabolites. On t he other hand, since PAH profile can vary substantially in different work s ites, a single BEI cannot apply to all workplaces. A simple equation was th erefore developed to establish BEIs for workers exposed to PAHs in differen t work environments by using a BEI already established for a given work env ironment and by introducing a correction factor corresponding to the ratio of the airborne concentration of the sum of benzo(a)pyrene (BaP) equivalent to that of pyrene. The sum of BaP equivalent concentrations represents the sum of carcinogenic PAH concentrations expressed as BaP using toxic equiva lent factors. Based on a previously estimated BEI of 2.3 mu mol 1-OHP mol(- l) creatinine for coke-oven workers, BEIs of 4.4, 8.0 and 9.8 mu mol 1-OHP mol(-1) creatinine were respectively calculated for vertical pin Soderberg workers, anode workers and pre-bake workers of aluminium plants and a BEI o f 1.2 mu mol 1-OHP mol(-1) creatinine was estimated for iron foundry worker s. This approach will allow the potential risk of cancer in individuals occ upationally exposed to PAHs to be assessed better.