Background There are limited epidemiological studies on emerging trends in suicide methodology relating to Internet promotion of toxic substances. We investigated time trends and demographic characteristics of deliberate self-poisonings with sodium nitrite/nitrate following Internet promotion for euthanasia in 2017 and a cluster of poisonings.
Methods Retrospective observational study of the National Coronial Information System (2000 – June 2020), Poisons Information Centres, toxicology services (2004 – June 2020) and a scoping review including Embase and MEDLINE (2000 – June 2020) for deliberate self-poisonings with sodium nitrite/nitrate. We examined survival, date, gender, age, setting, geographical location, history of a terminal or psychiatric illness, product.
Results We identified 66 deliberate self-poisonings, who were mostly male (65%) with a wide age distribution (median: 44 years; IQR: 24–66 years; range: 16–92 years; mode: 20–29 years). The majority had a fatal outcome (80%). A sudden and sustained step-increase in poisonings was seen from September 2017 (and the first death). Most cases (83%) had a psychiatric illness and no terminal illness (91%). There were 33 unique cases (mostly young adults) identified in the scoping review from eight countries.
Conclusions The promotion of suicide methodology was associated with a dramatic change in harms from sodium nitrite/nitrate in the past two decades. The signal generated by poisons centre cases was confirmed using national coronial data and pooled poisoning data.
Learning Outcomes State public health actions to date have focused on means restriction, improved antidote stocking and clinical education. National and international collaboration is needed for monitoring promoted lethal substances.