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.