1. Sources and Significance
The chemical N-nitrosodimethylamine (NDMA) has been identified as a probable human carcinogen by the U.S. Environmental Protection Agency. It is commonly found as a byproduct of industrial materials, such as liquid rocket fuel, lubricants, and pesticides. The general public can be exposed to NDMA by such sources as outdoor air, tobacco smoke, rubber products, cosmetics, and dietary consumption (e.g., cured meats, fish, cheese, and beer). The average concentrations of NDMA measured in various foods range from 90 to 100 ng/L for pasteurized milk, 600 to 1000 ng/kg for fried pork bacon, and 50 to 5900 ng/kg for beer. NDMA also has been detected in recycled water, wastewater, and potable water, and it may be formed by chlorine and chloramine disinfection processes.1,2 The formation mechanisms that produce NDMA also may form other nitrosamines. Seven other nitrosamines (see Table 6450:1) that are structurally related to NDMA and in some instances known to cause cancer in animals have been included in this method.