AbstractThe mutagenicity of the vicinity of an oil‐refining complex and a petrochemical complex was examined using the germinal revertant frequency ofZea mayswaxy‐C W22 and the somatic stamen hair system ofTradescantia. A 3‐year study was conducted at Wood River, Illinois, in 1978, 1979, and 1980, and a 1‐year study in 1979 at Beaumont, Texas. The studies conducted in 1978 registered the effects of airborne pollutants and possible soil pollutants. The studies in 1979 and 1980 registered only the effects of airborne pollutants. Elevated mutation frequencies ofZea mayscompared to various controls occurred in 1978, 1979, and 1980 at both complexes. The mutation frequencies ofZea mayswere particularly high, up to 26‐times control values. By contrast, the mutation frequencies ofTradescantiawere much lower, with maximum mutation frequencies five times cont