Detected in trace amounts in tobacco smoke: Druckney, Preussman, Naturwissenschaften 49, 498 (1962) DOI; and in various processed foods: Hedler, Marquardt, Food Cosmet. Toxicol. 6, 341 (1968) DOI PubMed; Friemuth, Glaeser, Nahrung 14, 357 (1970) DOI. Formed by the interaction of nitrite with diethylamine and by the action of nitrate-reducing bacteria. Industrial prepn: Reilly, DE 1085166 (1960 to du Pont), C.A. 56, 4594h (1962); Levering, Maury, US 3090786 (1963 to Hercules Powder); Minisci, Galli, Chim. Ind. (Milan) 46, 173 (1964). Hepatotoxicity and carcinogenicity studies: Schmaehl et al., Naturwissenschaften 54, 341 (1967); Grover, Fischer, Eur. J. Cancer 7, 77 (1971) PubMed; Bader et al., Arch. Geschwulstforsch. 37, 327 (1971) PubMed. General review: Magee, Barnes, Adv. Cancer Res. 10, 163-246 (1967) DOI PubMed.