Formation of dimethylnitrosamine from pesticides carrying methylated tertiary aminogroups in the presence of nitrite at pH 3

Pesticides and nitrite present in human food may be a hazard to man, since many pesticides are secondary or tertiary amines, which are known to form nitroso compounds in the presence of nitrite under conditions resembling those in the human stomach. Four tertiary amine pesticides-two dimethylurea derivatives, one thiuram disulphide and one phosphine compound-were incubated for 4 hr at 37°C in the presence of excess nitrite at pH 3. The reaction products were extracted with dichloromethane and were analysed qualitatively and quantitatively by infra-red spectrophotometry. nuclear-magnetic-resonance spectrometry, gas chromatography-mass spectrometry and light spectrophotometry. All four pesticides formed carcinogenic dimethylnitrosamine. the yields obtained being cycluron 4%, chloroxuron 3%, thiram 9% and dimefox 22%.