The first source is preformed nitrosamines present in meats, fish and other foods preserved with nitrites such as pickled, smoked, and salted food and in drinks like beer and whiskey 49.
La primera son nitrosaminas preformadas, presentes en carnes, pescados y otros alimentos preservados con nitritos, encurtidos ahumados, alimentos salados y bebidas alcohólicas como cervezas y whiskys 49.