Toxicity Profile for Nitrites (sodium and potassium salts) (1990)

Abstract

Sodium nitrite was an eye irritant in rabbits. Nitrites have a moderate to high acute oral toxicity in man and animals, producing methaemoglobinaemia which results in a poor oxygen supply to the body. Ingestion of a nitrite/nitrate mixture provoked dermatitis in some patients with a history of this complaint. There is some evidence that repeated ingestion of sodium nitrite produced lung and heart injury in rats, whereas the potassium salt caused tissue abnormalities in the adrenal glands. Studies of human populations have failed to show any convincing association between nitrite intake and cancer, the inconsistency of the findings from studies of stomach cancer arguing against a causative link. Animal feeding studies on the whole support the view that nitrite itself is non-carcinogenic since, although a few studies have found significant increases in tumour incidences in nitrite-exposed rats, there is no consistent pattern in the data either in the type of tumour seen or the gender affected. Nitrites may, however, react with compounds in the diet to form carcinogenic nitrosamines. Nitrites were genotoxic in bacterial tests (including Ames assays) and yeasts, and caused mutations and chromosome damage in mammalian cells in culture. Some feeding and injection studies have found chromosome damage in the cells of rats, mice, rabbits and hamsters. Repeated ingestion of sodium nitrite by pregnant rats, mice and guinea-pigs has caused maternal and foetal toxicity, but no increases in the incidences of offspring malformations have been seen.