Retrospective cohort analysis of nitrite and nitrate levels in postmortem biological samples after suspected suicide,...

Globally, reports of suicide by sodium nitrite poisoning have been growing. To determine whether sodium nitrite poisoning in suicide is an issue in the UK, we conducted an analysis of the cohort of cases analysed by the sole provider of nitrite assessment for postmortem sample in the UK.

Retrospective cohort analysis of biochemical measures for nitrite and nitrate anion in postmortem samples of 201 cases provided by HM coroners of suspected suicide over a period from March 2019 to August 2024. Secondary measures included sample collection and analysis dates, age and sex of deceased, sample number per case, sample types, and coroner regional location.

Of the 201 cases assessed by the laboratory during the inclusive time period, permission to include data was received from HM coroners for 164 of the cases. Suspected suicide by sodium (or potassium) nitrite/nitrate was confirmed in 87% of cases, with measured nitrite and/or nitrate concentrations ~100× normal physiological levels. Sex was known for 98% of cases and 68% were men. The age range was 14-82 years, and most (71%) cases were from Generation Z and Millennial generation. Cases came from across the UK, with the greatest proportion from Greater London, South East England, the Republic of Ireland, and the Midlands.

The data indicate that suicide associated with the ingestion of nitrite or nitrate salts is substantial in the UK, with a disproportionately high prevalence in young men. There is an urgent public health need for policy makers to consider strategies aimed at preventing and mitigating the harms associated with free access to these salts. This could include restrictions to purchase to facilitate prevention and adoption of easy to implement treatment protocols for both prehospital and emergency healthcare staff in suspected suicide by sodium nitrite/nitrate.