Use of blue cotton for detection of mutagenicity in human feces excreted after ingestion of cooked meat.

Fried ground beef has been shown to contain mutagens, and the major mutagenic component has been identified as 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx). Mutagens in feces of three adult volunteers were fractionated by treatment of the feces with blue cotton followed by chromatography on a carboxymethyl cellulose column. The chromatographic fraction corresponding to MeIQx in terms of the position of elution was examined for mutagenicity in S. typhimurium TA 98 with metabolic activation. When meals containing no heated meat were eaten, this fraction of feces showed little or no mutagenicity. On eating fried ground beef, the feces excreted in the next 2 days showed greatly increased mutagenicity in this fraction. By eating no-meat meals subsequent to the meat meal, the mutagenicity resumed the original low level on the fourth day after the meat meal. The components in the mutagenic fraction were analyzed by high-pressure liquid chromatography, and were shown to differ from MeIQx.