Mutagenicity in Salmonella typhimurium of N-3-methylbutyl-N-1-methyl-acetonyl-nitrosamine and N-methyl-N-benzylnitrosamine, N-nitrosation products isolated from corn-bread contaminated with commonly occurring moulds in linshien county, a high incidence area for oesophageal cancer in Northern China.

Two synthetic N-nitrosamines (N-3-methylbutyl-N-1-methyl acetonylnitrosamine and N-methyl-N-benzylnitrosamine), previously isolated from corn-bread which had been inoculated with moulds occurring in Linshien county, Northern China and subsequent nitrosation by sodium nitrite, were tested in Salmonella typhimurium strains TA1535 and TA100 in the presence of a liver postmitochondrial supernatant from Aroclor-treated rats. A concentration-dependent increase in the number of mutant colonies in both bacterial strains was observed when N-3-methylbutyl-N-1-methylacetonyl-nitrosamine was assayed in liquid suspension and N-methyl-N-benzylnitrosamine in plate incorporation assays. Our finding that mutagenic N-nitrosamines are present in foodstuffs that may be consumed in Linshien county are discussed in relation to the possible etiological role of these compounds in cancer of the oesophagus in that area.