Cyclic nitrosamine that occurs in food products and tobacco smoke. Prepn: F. C. Peterson, Ber. 21, 290 (1888). Carcinogenicity studies: H. Druckrey et al., Z. Krebsforsch. 69, 103 (1967); M. Greenblatt et al., J. Natl. Cancer Inst. 48, 1687 (1972); IARC Monographs 17, 313 (1978). Mechanism of mutagenicity: L. I. Hecker et al., Mutat. Res. 62, 213 (1979). Metabolism: R. C. Cottrell et al., Adv. Exp. Med. Biol. 136B, 1165 (1982).