In an occupational hygiene study of 25 workplaces with exposure to PAHs, 219 personal airborne samples were collected and showed the levels of nine carcinogenic PAHs ranged from 0.01 to 35.93 μg m−3 8 h TWA with a median of 0.12 μg m−3 8 h TWA. Levels of total PAH (the sum of 17 compounds) were found to be dominated by naphthalene and were insensitive to changing levels of nine carcinogenic PAHs. Measurement of BaP, a single PAH, was well correlated to levels of the nine carcinogenic PAHs and is a marker of exposure and risk. In this study the levels of BaP ranged from <0.01 to 6.21 μg m−3 8 h TWA with a median of 0.01 μg m−3 8 h TWA. Highest BaP exposures were seen in coke ovens where control of exposure relied on RPE.A control strategy based on an airborne exposure limit for BaP was not subsequently adopted by HSE for several reasons. Although the occupational hygiene data collected here suggests that BaP would be a useful tool as a marker for total PAH exposure in some industries, particularly those involving CTPV, it is a poor predictive marker for exposure to gas-phase compounds (2–4 ring compounds), which represent by far the largest group of most highly exposed workers. Control of exposure for coke ovens can best be achieved in a cost effective way with the use of RPE and specific guidance rather than enforce engineering solutions which, given current coke oven technology, may not be achievable. For these reasons the HSE thought it inappropriate to recommend an airborne occupational exposure standard based on BaP (HSE, 2003a, b).Urinary 1-OHP showed a good correlation with airborne BaP if dermal exposure and use of RPE were taken into account. Urinary 1-OHP levels ranged from less than the detection limit (0.5 μmol mol−1) to 60 μmol mol−1 with a mean of 2.5 μmol mol−1 and a median less than the detection limit. Highest levels of urinary 1-OHP were found in timber impregnators using creosote and workers using coal tar where there was both dermal and inhalation exposure. Excluding timber impregnation, 90% of urinary 1-OHP levels from 207 workers in 24 workplaces were <4 μmol mol−1 and this has been adopted as a biological monitoring guidance value in the UK. Using the observed correlation between urinary 1-OHP and airborne BaP, a level of 1-OHP of 4 μmol mol−1 is roughly equivalent to an airborne BaP level of 0.26 μg m−3. Biological monitoring for PAHs may be particularly useful where there is potential for dermal exposure or where control relies on RPE; however, a combination of biological and airborne measurements will be required to determine the effectiveness of control systems more fully.
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