Urinary polycyclic aromatic hydrocarbon metabolites as biomarkers to woodsmoke exposure - results from a controlled exposure study.

Woodsmoke contains harmful components - such as fine particulate matter (PM2.5) and polycyclic aromatic hydrocarbons (PAHs) - and impacts more than half of the global population. We investigated urinary hydroxylated PAH metabolites (OH-PAHs) as woodsmoke exposure biomarkers in nine non-smoking volunteers experimentally exposed to a wood fire. Individual urine samples were collected from 24-h before to 48-h after the exposure and personal PM2.5 samples were collected during the 2-h woodsmoke exposure. Concentrations of nine OH-PAHs increased by 1.8-7.2 times within 2.3-19.3 h, and returned to baseline approximately 24 h after the exposure. 2-Naphthol (2-NAP) had the largest post-exposure increase and exhibited a clear excretion pattern in all participants. The level of urinary OH-PAHs, except 1-hydroxypyrene (1-PYR), correlated with those of PM2.5, levoglucosan and PAHs in personal PM2.5 samples. This finding suggests that several urinary OH-PAHs, especially 2-NAP, are potential exposure biomarkers to woodsmoke; by contrast, 1-PYR may not be a suitable biomarker. Compared with levoglucosan and methoxyphenols - two other urinary woodsmoke biomarkers that were measured in the same study and reported previously - OH-PAHs might be better biomarkers based on sensitivity, robustness and stability, particularly under suboptimal sampling and storage conditions, like in epidemiological studies carried out in less developed areas.