[Nutritional and toxicologic impact of nitrates and nitrites administered chronically (6 months) in the rat]

It has been made a toxicological, nutritional and histological study of rats fed ad libitum, for six months, with a diet containing respectively (per 100 g of dry food): 0, 0,5 and 5% of NO3- ion and 0, 0,05 and 0,5% of NO2- ion. For each group of treated animals we have paired groups of control animals fed with a diet including the same doses of sodium as NaCl. At the highest dose studied, nitrates and nitrites induce a significative loss of weight during two first months of intoxication, but they do not impair noticeably the classic nutritional parameters of nitrogen metabolism, established at different periods of intoxication (0, 2, 4 and 6 months). Besides, dietary ingestion of relatively important quantities of NO3- and NO2- ions does not induce notable modifications of body composition and blood formula, showing an important adaptation of treated animals. Last, histological observations give evidence to a certain irritation (mucus, oedema) of the anterior section of digestive tract (especially stomach with nitrites), some attacks (essentially with nitrates) of thyroid gland (possible competition with iodine) and kidneys (increased diuresis); but the essential impact, with nitrates and nitrites, is situated at the spleen level, with an important liberation of iron and the trace of haemorrhagic zones, testifying to the chronic struggle of treated animals against methemoglobinemia.