Nitrites naturaly occur as part of nitrogen cycles. Nitrite ion is very unstable and in aeration zone under the oxygen oxidizes in nitrates, with presence of Nitrobacteria. It is using in industry as food additives, especially in meat and cheese. Also it is using as sons and oxidation agents in chemical industry.
Origin in water
Nitrites are in underground waters in inappreciable quantities. High contents of this ion can occur during the process of ammoniac and organic compounds, and also during nitrates reduction in nitrites. Oxidation of ammoniac compounds is under the nitrifying bacteria. Nitrites do not find in significant quantities in surface waters because of oxidation to nitrates. When the nitrites find in important content in water, it is the sign of pollution with waste waters and bacteria and inadequate disinfection. Nitrites can find in waste and decanted waters from agriculture surface and atmospheric canalisation.
Partial reduction of nitrites to nitrates at people happens in saliva for all ages and in gastrointestinal channel at babies in first three months of life. Because of that, babies to three months are more sensitive because they transform 100% ingestiranih nitrates to nitrites, until 10% transform at adults and children. Nitrates reduction in nitrites with stomach bacteria is bigger at babies, because of small stomach acidity.
Nitrites toxicities manifests through the vasodilator/cardiovascular effects with high doses and methaemoglobinemiom- syndrome of blue kids with small doses. Nitrites in blood oxidise haemoglobin in met haemoglobin which do not transport oxygen to the tissues. That manifest with cyanosis and in high concentration with asphyxia (stop of breathing).
Maximal allowable concentrations
According to recommendations of EU (Directive 98/83/EC) limitary value for nitrites can enlarge on 0,5 mg/1 after chlotaminisation and for conditions when the total of [NCV] /50 + [NO2-] /3 is smaller or equal with 1. Limitary values for nitrites is 0,03 mg/1(Sl. list SRJ 42/98).