Survey of Fluid and Nonfat Dry Milks for N-Nitrosamines

A limited survey of milk and dairy products was undertaken to determine the presence of volatile N-nitrosamines, a class of compounds carcinogenic to a broad range of animal species. Nitrosamines were detected and quantitated by a gas liquid chromatograph interfaced with a Thermal Energy Analyzer. Detectable N-nitrosodimethylamine, the only nitrosamine found, ranged from .05 ppb for whole milk to .30 ppb for nonfat dry milk. No N-nitrosodimethylamine was detected in raw milk, whereas 11 of 21 samples of pasteurized milk contained apparent N-nitrosodimethylamine at a mean .10 ppb. N-nitrosodimethylamine also was detected, but not confirmed by mass spectrometry, in evaporated and condensed milk with means .32 ppb and .58 ppb and in 9 of 10 nonfat dry milk samples with a mean of 1.69 ppb. Upon reconstitution condensed milk and nonfat dry milk contained N-nitrosodimethylamine comparable to that in pasteurized milk. No N-nitrosodimethylamine was detected in cultured milk products such as buttermilk and yogurt.