Biological monitoring as a useful tool for the detection of a coal-tar contamination in bitumen-exposed workers

The Use of Human Biomonitoring to Assess Occupational Exposure to PAHs in Europe: A Comprehensive Review

Polycyclic aromatic hydrocarbons (PAHs) are among the chemicals with proven impact on workers' health. The use of human biomonitoring (HBM) to assess occupational exposure to PAHs has become more common in recent years, but the data generated need an overall view to make them more usable by regulators and policymakers. This comprehensive review, developed under the Human Biomonitoring for Europe (HBM4EU) Initiative, was based on the literature available from 2008-2022, aiming to present and discuss the information on occupational exposure to PAHs, in order to identify the strengths and limitations of exposure and effect biomarkers and the knowledge needs for regulation in the workplace. The most frequently used exposure biomarker is urinary 1-hydroxypyrene (1-OH-PYR), a metabolite of pyrene. As effect biomarkers, those based on the measurement of oxidative stress (urinary 8-oxo-dG adducts) and genotoxicity (blood DNA strand-breaks) are the most common. Overall, a need to advance new harmonized approaches both in data and sample collection and in the use of appropriate biomarkers in occupational studies to obtain reliable and comparable data on PAH exposure in different industrial sectors, was noted. Moreover, the use of effect biomarkers can assist to identify work environments or activities of high risk, thus enabling preventive risk mitigation and management measures.

Comparison of gaseous polycyclic aromatic hydrocarbon metabolites according to their specificity as biomarkers of occupational exposure: Selection of 2-hydroxyfluorene and 2-hydroxyphenanthrene

Exposure to Polycyclic Aromatic Hydrocarbons (PAHs) occurs by respiratory, digestive and dermal absorption. Biomonitoring takes all pathways into account but sensitive and specific biomarkers are required. Different gaseous PAHs metabolites were used due to their abundance in the atmospheric mixtures but none of them were selected as better biomarker than the others. To identify the best candidates for assessing occupational airborne exposure, relation between atmospheric levels of Naphtalene, Fluorene and Phenanthrene and urinary metabolites concentrations was studied in a carbon electrode workers group. Linear mixed effects models were built to select explanatory variables and estimate variance component. Urinary creatinine was a predictor of metabolites levels confirming the importance of diuresis for interpreting results. High significance of pre-shift sampling time combined with positive coefficients of post-shift indicated that urine should be sampled at the end of the workday in association with pre-shift urine to avoid misinterpretations. Among the 10 metabolites studied, urinary 2-hydroxyfluorene and 2-hydroxyphenanthrene showed the highest increase of variance explained by models after inclusion of individual atmospheric levels as explanatory variable. Priority could be given to 2-hydroxyfluorene due to higher excretion levels than 2-hydroxyphenanthrene.

The Human Bitumen Study: executive summary

Bitumen has attracted attention from the scientific community and regulating agencies. The debate on health effects of exposure to vapours and aerosols of bitumen during the hot application of bitumen ranges from respiratory and neurological effects to carcinogenicity. In 2000, the German Hazardous Substances Committee (AGS), in collaboration with the German Bitumen Forum, initiated the examination of a group of mastic asphalt workers and a same number of construction workers without exposure bitumen using a cross-shift design. The study was then extended to the Human Bitumen Study, and the recruitment was finished in 2008 after examination of 500 workers on 80 construction sites. Three hundred and twenty workers exposed to vapours and aerosols of bitumen at high processing temperatures and 118 workers at outdoor construction sites were included. In the Human Bitumen Study external exposure to vapours and aerosols of bitumen, internal exposure to PAH by analysing urinary 1-hydroxypyrene, the sum of hydroxyphenanthrenes and the sum of 1- and 2-hydroxynaphthalenes, irritative effects in the upper and lower airways and genotoxic effects in blood cells were investigated. The study turned out to be one of the largest investigations of workers exposed to vapours and aerosols of bitumen under current exposure conditions. The present paper summarizes its background and main topics.

Urinary metabolites of polycyclic aromatic hydrocarbons in workers exposed to vapours and aerosols of bitumen

Urinary hydroxylated metabolites of polycyclic aromatic hydrocarbons (PAH) were investigated as potential biomarkers of bitumen exposure in a cross-shift study in 317 exposed and 117 non-exposed workers. Personal measurements of the airborne concentration of vapours and aerosols of bitumen during a working shift were weakly associated with post-shift concentrations of 1-hydroxypyrene (1-OHP) and 1-, 2+9-, 3- and 4-hydroxyphenanthrenes (further referred to their sum as OHPHE), but not 1- and 2-hydroxynaphthalene (OHNA). Smoking showed a strong influence on the metabolite concentrations, in particular on OHNA. Pre-shift concentrations of 1-OHP and OHPHE did not differ between the study groups (P = 0.16 and P = 0.89, respectively). During shift, PAH metabolite concentrations increased in exposed workers and non-exposed smokers. Statistical modelling of post-shift concentrations revealed a small increase in 1-OHP by a factor of 1.02 per 1 mg/m(3) bitumen (P = 0.02) and 1.04 for OHPHE (P < 0.001). A group difference was observed that was diminished in non-smokers. Exposed non-smokers had a median post-shift 1-OHP concentration of 0.42 μg/l, and non-smoking referents 0.13 μg/l. Although post-shift concentrations of 1-OHP and OHPHE were slightly higher than those in the general population, they were much lower than in coke-oven workers. The small content of PAHs in vapours and aerosols of bitumen, the increasing use of additives to asphalt mixtures, the strong impact of smoking and their weak association with airborne bitumen limit the use of PAH metabolites as specific biomarkers of bitumen exposure.

Highly sensitive routine method for urinary 3-hydroxybenzo[a]pyrene quantitation using liquid chromatography-fluorescence detection and automated off-line solid phase extraction

Many workers and also the general population are exposed to polycyclic aromatic hydrocarbons (PAHs), and benzo[a]pyrene (BaP) was recently classified as carcinogenic for humans (group 1) by the International Agency for Research on Cancer. Biomonitoring of PAHs exposure is usually performed by urinary 1-hydroxypyrene (1-OHP) analysis. 1-OHP is a metabolite of pyrene, a non-carcinogenic PAH. In this work, we developed a very simple but highly sensitive analytical method of quantifying one urinary metabolite of BaP, 3-hydroxybenzo[a]pyrene (3-OHBaP), to evaluate carcinogenic PAHs exposure. After hydrolysis of 10 mL urine for two hours and concentration by automated off-line solid phase extraction, the sample was injected in a column-switching high-performance liquid chromatography fluorescence detection system. The limit of quantification was 0.2 pmol L(-1) (0.05 ng L(-1)) and the limit of detection was estimated at 0.07 pmol L(-1) (0.02 ng L(-1)). Linearity was established for 3-OHBaP concentrations ranging from 0.4 to 74.5 pmol L(-1) (0.1 to 20 ng L(-1)). Relative within-day standard deviation was less than 3% and relative between-day standard deviation was less than 4%. In non-occupationally exposed subjects, median concentrations for smokers compared with non-smokers were 3.5 times higher for 1-OHP (p<0.001) and 2 times higher for 3-OHBaP (p<0.05). The two urinary biomarkers were correlated in smokers (ρ=0.636; p<0.05; n=10) but not in non-smokers (ρ=0.09; p>0.05; n=21).