Mutagenicity of expectorate from workers in a coke plant.

Methanol extracts of hydrolyzed expectorate samples from workers in a coke plant were tested with the Salmonella reversion assay. The expectorates from exposed smokers (but also to a certain extent from exposed non-smokers) were mutagenic; however, the control samples from both smokers and non-smokers were not. The positive results produced by the expectorate samples from exposed smokers suggest a synergistic relationship between exposure to air pollution in the working atmosphere and smoking.