Nonsmoking women in Xuan Wei County, Yunnan Province, China who use smoky coal 
for cooking and heating in poorly ventilated homes have the highest lung cancer 
mortality rate in China, and their lung cancer is linked epidemiologically to 
their use of smoky coal. The emissions contain 81% organic matter, of which 43% 
is polycyclic aromatic hydrocarbons (PAHs). Exposure assessment and molecular 
analysis of the lung tumors from nonsmoking women who use smoky coal strongly 
indicate that PAHs in the emissions are a primary cause of the elevated lung 
cancer in this population. Here we have determined the mutation spectra of an 
extract of smoky coal emissions in Salmonella TA98 and TA100; the extract was 
not mutagenic in TA104. The extract was 8.7 x more mutagenic in TA100 with S9 
than without (8.7 rev/microg versus 1.0 rev/microg) and was >3 x more mutagenic 
in TA100 than in TA98--consistent with a prominent role for PAHs in the 
mutagenicity of the extract because PAHs are generally more mutagenic in the 
base-substitution strain TA100 than in the frameshift strain TA98. The extract 
induced only a hotspot mutation in TA98; another combustion emission, cigarette 
smoke condensate (CSC), also induces this single class of mutation. In TA100, 
the mutation spectra of the extract were not significantly different in the 
presence or absence of S9 and were primarily (78-86%) GC --> TA transversions. 
This mutation is induced to a similar extent by CSC (78%) and the PAH 
benzo[a]pyrene (B[a]P) (77%). The frequency of GC --> TA transversions induced 
in Salmonella by the extract (78-86%) is similar to the frequency of this 
mutation in the TP53 (76%) and KRAS (86%) genes of lung tumors from nonsmoking 
women exposed to smoky coal emissions. The mutation spectra of the extract 
reflect the presence of PAHs in the mixture and support a role for PAHs in the 
induction of the mutations and tumors due to exposure to smoky coal emissions.