Four cases of sodium nitrite suicidal ingestion. A new trend and a relevant forensic pathology and toxicology challenge

Sodium nitrite (NaNO2) is an inorganic compound commonly used as a food additive, antifreeze admixture, and fertilizer. Its toxicity mechanism is mainly represented by the oxidation of ferrous iron to ferric iron of one of the four heme structures in haemoglobin with the onset of methaemoglobin. The mechanism of death by sodium nitrite toxicity is severe hypoxia. We present four cases of suicidal sodium nitrite ingestion that closely occurred within a two months-period. Self-poisoning with sodium nitrite actually represents an increasing trend in nitrates' related deaths. In order to reach a precise diagnosis of NaNO2 intoxication, a complete toxicological analysis should be carried out including not only MetHb blood levels but also nitrites and nitrites in standard or alternative matrices as a routine procedure. Autopsy should be carefully performed to detect common indicators of hypoxia or more rarely evident typical by themselves-non specific signs of sodium nitrite toxicity. Suicidal manner of death should be carefully considered when circumstantial data support that ingestion of large amounts of NaNO2 occurred as a consequence of a self-injurious behaviour. Relevant informations include victim's previous Internet or book researches about paths to follow to commit suicide with sodium nitrate, employment and past medical history, with strong regard to psychiatric diseases as well as eventual taking psycotropic drugs. Finally, an accurate integration of autoptic and toxicological results with circumstantial data is necessary to make correct diagnosis of death due to acute respiratory failure secondary to suicidal sodium nitrite ingestion.