From preservative to poison

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Chemistry World has intentionally omitted some chemical names in this article. 

To alert and inform their colleagues, experts with New York City’s Bureau of Preventable Diseases and Bureau of Food and Drugs published a case report in the American Journal of Public Health (AJPH) in 1945.¹ Wartime brought with it a variety of public health concerns including – but not limited to – typhoid fever, dysentery, smallpox and malaria.² None of these maladies was the focus of the AJPH report. It was a different type of outbreak altogether.

On a September day in 1944, 11 ‘old men’ arrived by ambulance to a New York City hospital with nearly identical symptoms.¹ All had low temperatures and blood pressure, cold extremities, and a bluish or grey tinge to their skin indicating not enough oxygen in circulating blood (cyanosis). Most had vomited, all had diarrhoea, and about half had lost consciousness shortly after becoming ill. Treatment for their symptoms – which included stomach pumping and oxygen therapy – resulted in 10 patients recovering. One man, aged 82, died the morning after with an autopsy revealing bronchopneumonia plus ‘diffuse mahogany brown discoloration of the organs’. This brown discoloration – along with the noticeable cyanosis – pointed to poisoning.

Each man had eaten oatmeal for breakfast at the same poorly rated restaurant. Within a half hour of eating, each man fell ill. An investigation would reveal the issue was not the oatmeal or the water used to cook it, but the salt used to season it.

The cook stated he refilled the salt can from a bulk supply on a shelf that contained two containers – one filled with a white solid and the other ‘a yellowish looking salt’.¹ The restaurant’s owner said the white solid was table salt, while the yellowish one was used to cure meat. Testing would reveal the white solid was indeed sodium chloride, while the yellowish solid was largely composed of a substance commonly used to preserve meat, with very low levels inhibiting the growth of anaerobic microorganisms such as Clostridium botulin.^1,3,4 APJH report authors noted that the chemical was an approved additive for curing meat ‘provided the finished product contains not more than 200ppm’.¹

Toxicological testing supported a diagnosis of poisoning. Pooled blood samples from the 10 survivors indicated the presence of the substance. Blood serum specimens from each patient were examined spectroscopically and ‘absorption bands for methaemoglobin were found in all’.¹ Methaemoglobin is an ‘aberrant form of haemoglobin’ where the ferrous iron (Fe²⁺) of haemoglobin has been oxidised to the ferric iron (Fe³⁺), impairing oxygen transport and causing asphyxia.⁵ A variety of substances are known that can directly or indirectly oxidise haemoglobin to methaemoglobin.⁶

High levels of methaemoglobin lead to methaemoglobinemia, a condition marked by cyanosis and chocolate-brown blood. As methaemoglobin percentages rise, symptoms increase in number and severity. Methaemoglobin percentages above 70% are usually fatal.^5,7,8 To bring down dangerous methaemoglobin levels today, a body weight dependent dose of methylene blue delivered intravenously is the go-to antidote therapy barring contraindications.^3,7–11 Methylene blue is reduced by NADPH-dependent methaemoglobin reductase to the colourless leucomethylene blue, which reduces the ferric iron back to ferrous iron, enabling healthy levels of oxygen transport by restored haemoglobin.^3,10,12,13 While methylene blue was used to treat metheamoglobinemia in a handful of US reports in the 1930s,¹⁰ its use was not mentioned in the AJPH report.

The authors of the AJPH report noted the striking similarity of the few published poisoning cases relating to this chemical at the time in both symptoms and manner. Most involved mistakenly using the substance in place of table salt. About 75 years later, other experts would identify a poisoning trend that was not accidental but intentional.

Intentional ingestion

Ramping up in 2019, worldwide case reports in forensic and medical journals sought to raise the alarm on the rise in cases of the intentional ingestion of this substance.^{3,7,9,14–17} As in decades past, it still is a widely used preservative.^{3,7–9,14,17}

A report from Portugal in 2020 was identified by the authors as the first fatal case in the literature involving procurement of a ‘suicide kit’ composed of this substance from an online source.⁷ 

Canadian Kenneth Law, a former chef and onetime engineer allegedly sold and shipped over 1000 such ‘suicide packets’ to recipients in 40 countries that he met in online forums. An international investigation led to Law’s arrest in May 2023. Initially charged by Canadian authorities with 14 counts of first-degree murder, Law pled guilty in May 2026 to multiple charges of ‘counselling or aiding 14 suicides in the province, admitting he ran websites that sold suicide paraphernalia to vulnerable people who later died.’

Law’s sentencing hearing began last week in Ontario, Canada with the court hearing 70 impact statements from victims’ loved ones. Dubbed a ‘poison seller’, Law’s sentencing hearing is scheduled to continue in November.

Update: This article was updated by Chemistry World on 1 October 2026 to remove references to some named chemical substances in line with the Samaritans’ guidance on best practice for the media on reporting suicides and suicide prevention