Most
squamous cell carcinomas of the oesophagus in low-risk populations are attributable to alcohol and tobacco consumption, but the aetiologic agents in many high-risk populations have yet to be definitively identified. Linxian, China has some of the highest oesophageal
cancer rates in the world. Recent studies suggest that an association exists between high-level exposure to carcinogenic
polycyclic aromatic hydrocarbons (PAHs), such as
benzo[a]pyrene (B[a]P), and the development of oesophageal
cancer. The inhabitants of this high-risk region extensively use
coal and wood for cooking and heating in unvented stoves, and thus may be exposed to PAHs produced during the incomplete combustion of these fuel sources. High levels of B[a]P were recently detected in staple food samples from Linxian and histopathologic changes that may be associated with PAH exposure have also been identified in oesophagectomy specimens from the region. In an effort to determine whether this high-risk population is exposed to high levels of PAHs, voided urines from non-smokers (n = 22) without occupational exposure were collected and analysed using immunoaffinity chromatography and synchronous fluorescence spectroscopy for
1-hydroxypyrene glucuronide, a PAH metabolite and index
biomarker for mixed PAH exposure. The median urine
1-hydroxypyrene glucuronide concentration (2.06 pmol ml(-1)) was equivalent to concentrations detected in current smokers. To the authors' knowledge, this represents the first report of elevated urine 1-hydroxpyrene
glucuronide concentrations in Linxian, and the first
biologic confirmation that the inhabitants of this rural, non-industrial, high oesophageal
cancer risk region are exposed to carcinogenic PAHs.