Chemical carcinogens, 1. Nitrosamine compounds: strictly speaking, should be called N-nitroso compounds. It is widely distributed in nature, in animals studied are 300, of which 75% of gastric cancer has led directly to the role, its predecessor, nitrite and secondary amines. Nitrite, nitrate mainly from food, especially after the heavy use of nitrogen fertilizer in vegetables, high levels of nitrate.
Nitrate into the stomach by nitrate reductase-positive bacteria to be reduced to nitrite. Secondary amine as the catabolism of protein in food products under acidic conditions, amines by nitrosation and chemical synthesis of nitrosamine compounds; in neutral conditions, catalyzed by the bacterial nitrification and biological amines synthesis of nitrosamine compounds. Chemical synthesis and in vivo biosynthesis of endogenous compounds known as nitrosamines nitrosamines compounds from food, smoking, industrial and domestic supplies and the environment as exogenous intake of nitrosamine compounds endogenous than exogenous exposure were much higher. Bacteria directly involved in the synthesis of nitrosamine compounds. These bacteria under acidic conditions in the growth and reproduction is not easy, but gastric acid in atrophic gastritis in patients with low or absent in the stomach and the amount of nitrate reductase-positive bacteria was 2 times normal, which makes the stomach nitrosamine compounds concentration increased.
2. Polycyclic aromatic: strange compounds: these compounds are highly carcinogenic substances, such as exists in the 3 tobacco, cattle benzo can cause lung cancer are. It is reported that the incidence of lung cancer in smokers than non-smokers 3.76 times. Dungal reported death from cancer in Iceland confirmed by autopsy, of which 1 / 3, died of stomach cancer. Because Iceland is rich in excellent fish, squatting fish, in addition to the fishing season when canned, the remaining large number of fish is made into smoked fish. According to the analysis of smoked fish per 1000g containing 3,4 – benzo is 2.1 tons, equivalent to 250 of the substance contained in cigarette smoke volume, suggesting that a high incidence of gastric cancer in Iceland, eating smoked fish may be related with local residents.
Chemical carcinogens, 3. Asbestos fiber: Asbestos can cause mesothelioma occurs in addition, there are induced effects of gastric cancer. In the past, the Japanese like porridge mixed with a small amount of talcum powder, so that there is smooth in the sense of eating, allegedly containing talc per gram of 3.7 million asbestos fibers, so suggested that countries with high gastric cancer in Japan may be related to the diet habits.