Humans are exposed to preformed N-nitroso compounds (NOC)‡, but also to a wide range
of precursors and nitrosating agents which can react in vivo to form potentially carcinogenic
NOC and diazo compounds. Nitrite, nitrate and nitrosating agents can also be synthesized
endogenously in enzymic reactions mediated by bacteria, activated macrophages and
neutrophils. The latter two cell types generate, via the enzyme nitric oxide synthase, the nitric
oxide radical that is involved in cytotoxicity, and is believed to be involved in formation of …