Introduction:
Nitrogen, as the main component of the atmosphere, and a component of the construction of DNA and proteins of all organisms, is among the most important elements in nature. The content of nitrogen compounds in soil decides about its fertility. Therefore, nitrogen compounds are widely applied in the form of artifi cial fertilizers in order to increase yield. An excess of the fertilizers used, unbalanced with the intensity of plant production, may become the source of contamination of surface waters and food with nitrates. Nitrogen compounds are also applied as food preservatives, preventing the development of Clostridium botulinum bacteria in food products (pickling meat). While processing conserved food products, nitrates enter into the reaction with amines which are present in meat and form carcinogenic nitrosamines. There are reports describing the relationship between nitrosamines and the development of gastrointestinal cancer (gastric cancer, colorectal cancer, oesophageal cancer). In addition, the presence of heavy metals salts in artifi cial fertilizers is also signaled, such as lead, arsenic and cadmium which, among other things, exert an effect on the development of cancer of the gastrointestinal tract and urinary system. The epidemiological situation and etiologic factors of gastric, colorectal and esophageal cancer are briefl y presented.