N-Nitrosamines as Environmental Carcinogens

Among carcinogens the N-nitroso compounds are the most broadly acting and among the most potent. They comprise the directly acting nitrosamides and the systemically acting nitrosamines, which require enzymic activation for their carcinogenic action. This difference between the two types of N-nitroso compound is also shown in bacterial mutagenesis. More than a hundred N-nitroso compounds have been tested for carcinogenic activity and most of them have induced tumors in rats; a much smaller number has been tested in hamsters, mice or guinea pigs and, again, most of those tested have been carcinogenic. Among the N-nitroso compounds tested for mutagenesis in bacteria there has been a fairly good qualitative correlation with carcinogenicity, although there have been a number of significant exceptions, particularly in carcinogenic nitrosamines which have not been mutagenic ( 1, 2 ). N-nitroso compounds elicit a varied response from different animals, often giving rise to entirely different tumors in rats compared