Most nitrosamines (or N-nitrosamines) are organic compounds found to be carcinogenic in animal tests. Nitrosamines are formed by the reaction of nitrite and secondary amines.
Nitrite are mainly used as preservatives and seconday amines mainly arise from the degradation of proteins. Nitrite and nitrosamine intake are associated with risk of gastric cancer and oesophageal cancer. Exposure to nitrosamines are mainly associated with tobacco or dietary exposure. The formation of nitrosamines is shown in figure below.