A potent mutagen detected in human feces: W. R. Bruce et al., Cold Spring Harbor Conf. Cell Proliferation 3, 1641 (1977). Isoln and characterization: T. D. Wilkins et al., Am. J. Clin. Nutr. 33, 2513 (1980). Structure: N. Hirai et al., J. Am. Chem. Soc. 104, 6149 (1982). Implicated in human colon cancer: Chem. Eng. News 60, 22 (Sept. 27, 1982); T. H. Maugh, Science 218, 363 (1982).