Polycyclic aromatic hydrocarbons identified in soot extracts from domestic coal-burning stoves of Henan Province, China

Using high-pressure liquid chromatography with ultraviolet-visible diode-array detection, we have analyzed polycyclic aromatic hydrocarbons (PAH) in the dichloromethane extracts of soot deposits from coal-burning stoves in several homes of Henan Province, China - including Linxian County, where esophageal cancer rates are some of the highest in the world. Thirty-two individual polycyclic aromatic compounds, ranging in size from three to eight fused aromatic rings, have been unequivocally identified among the soot extract components - including 20 benzenoid PAH, 6 fluoranthene benzologues, 1 cyclopentafused PAH, 1 indene benzologue, 3 oxygenated PAH, and 1 ring-sulfur-containing aromatic. Most of the identified compounds have been observed before among the products of laboratory coal pyrolysis experiments, but two of the components, the six-ring C₂₄H₁₄ naphtho[1,2-b]fluoranthene and the eight-ring C₃₀H₁₆ tribenzo[e,ghi,k]perylene, have never before been documented as products of coal in any system. All of the Henan coal soot extracts are remarkably similar qualitatively in that they contain the same set of identified PAH, but absolute levels of individual species vary by up to 5 orders of magnitude, from sample to sample. The bulk of the identified component mass in all of these soot extracts lies in the five- and six-ring PAH - the largest single class being the family of five-ring C₂₀H₁₂ isomers, to which the samples' most abundant components, benzo[b]fluoranthene and benzo[e]pyrene, belong. The five- and six-ring PAH also account for the majority of the samples' known mutagens. The three strong mutagens identified in these soot samples are the C₂₀H₁₂ benzo[a]-pyrene and two C₂₄H₁₄ PAH, dibenzo[a,e]pyrene and naphtho[2,1-a]pyrene. Seven moderate mutagens are found among the C₂₀H₁₂, C₂₂H₁₂, C₂₂H₁₄, and C₂₄H₁₄ PAH. A major class of mutagens, the cyclopenta-fused PAH, appears to be absent from these samples, but our detection of an oxidation product of the major mutagen cyclopenta[cd]-pyrene-itself mutagenic-suggests that these soot deposits may contain additional mutagenic cyclopentafused PAH oxidation products as well.