Summary: Health experts are calling for stricter regulations on the use of sodium nitrate, a product commonly used in meat curing that has been linked to suicide and increased rates of poisoning.
A recent spike in fatal sodium nitrite poisoning has prompted some health experts to call for tighter regulation of the substance. Sodium nitrite is a white salt commonly used in curing meat. But in recent years it has also been used as a poison in suicide cases.
Ontario had at least 28 deaths from sodium nitrite poisoning between 1980 and 2020, most of them in the last two years of that period. The Alberta Health Service poison center, which also serves the Northwest Territories and Saskatchewan, saw at least two sodium nitrite poisoning cases last year that caused serious harm, and two more this year.
These numbers are likely underestimated as Canada does not collect comprehensive data on sodium nitrite poisoning.
Toxicovigilance Canada, a poison control network led by Health Canada, was unable to share national figures, citing “no national data from coroners, coroners, or poison centers.” Poison centers do not have a clear picture of the problem either, as it is not mandatory for medical staff to share information about the poisonings they are treating.
In the United States, the National Poison Data System recorded 47 cases of sodium nitrite poisoning between 2015 and 2020. As in Ontario, most of these poisonings occurred in 2019 and 2020.
Online forums promoting poisoning
Sodium nitrite poisoning was virtually unheard of until recently, says Eric McGillis, a Calgary-based medical toxicologist with Alberta’s Poisons and Drugs Information Service. “However, cases are increasing exponentially in recent years.”
The trend seems to be driven by online forums detailing how to dose sodium nitrite for suicide.
Amazon became a major marketplace for the substance, leading to lawsuits from survivors. (Sodium nitrite no longer appears in the top search results on the site.) Other online marketplaces, including Etsy and eBay, have banned the substance from being sold.
Dana Saleh, a fourth-year student of respiratory medicine at the University of Calgary, says it’s concerning to see online communities encouraging people to kill themselves. She is the lead author of a case report of a 20-year-old man who ingested sodium nitrite purchased online as part of a “suicide kit.”
“These are very vulnerable people to begin with, and then they have access to these websites that basically teach them how to commit suicide,” Saleh says. “It comes assembled and is easily accessible.”
Sodium nitrite poisoning can be difficult to identify, and deaths can appear natural without further investigation or evidence suggesting suicide. A lethal dose can vary widely, Saleh notes. “It can actually be from a very small dose to a very large dose, so it’s unpredictable how deadly it is, and we know that even at a lower dose it can certainly be life-threatening.”
What doctors should look out for
Sodium nitrite ingestion causes methemoglobinemia — a blood disorder in which insufficient oxygen is delivered to cells — which can quickly lead to hypoxia and sometimes death. Many patients have heart rates above 100 beats per minute and bluish-purple skin. Other symptoms include low oxygen levels and chocolate-colored blood. The antidote is the rapid use of methylene blue.
Last May, the Institute for Safe Medication Practices Canada recommended that all emergency rooms should have methylene blue available to treat patients with sodium nitrite poisoning. Margaret Thompson, medical director of poison centers in Ontario, Manitoba and Nunavut, endorsed the bulletin after incidents where confusion about methylene blue availability and dosing led to delays in treatment. Because the food industry uses sodium nitrite for legitimate purposes, Thompson says preventing poisoning by restricting access to the substance could be a challenge.
However, some doctors argue that lawmakers could step in to block online purchases of sodium nitrite.
“There has to be tires before anyone resorts to sodium nitrite,” says Yub Raj Sedhai, clinical assistant professor at Virginia Commonwealth University. In April, Sedhai and his colleagues published a case report of their experience treating a 37-year-old man who was taking sodium nitrite purchased from Amazon.
“It would be fair to interview a person who is buying sodium nitrite to help them,” says Sedhai. Because the substance is readily available and can be confused with table salt, people can also “unknowingly overdose,” Sedhai and colleagues noted in their case report.
Could restricting sales of sodium nitrite save lives?
The UK has listed sodium nitrite as a “reportable substance”, meaning sellers must report suspicious purchases to the authorities. However, it is unclear whether such measures reduce intentional poisoning.
After Sri Lanka enacted bans on certain pesticides, the country saw its overall suicide rate fall by 70%.
“It certainly worked in Sri Lanka, where there were a lot of pesticide suicides,” says Thompson. But restrictions on other substances haven’t had the same effect, she says. “In the UK, for example, where you can’t buy more than 30 acetaminophen at a time, that hasn’t reduced the number of acetaminophen poisonings.”
An alternative to bans is to sell dangerous substances in small quantities – enough for those who need them for legitimate reasons, but not enough to cause death. This is not necessarily true for sodium nitrite, as small amounts can be fatal. And regardless, Thompson says, “determined people might buy multiple packages.”
Another option is to restrict sales to individuals while still allowing sales to businesses.
According to a Health Canada spokesman, “Regulatory oversight of sodium nitrite is divided between federal, provincial and territorial agencies depending on the end use of the product sold.” When asked what Health Canada is doing about intentional poisoning, the spokesman told CMAJ in an e- Mail says the government is focused on supporting mental health and well-being.
“Regulatory action is not the appropriate tool to address this issue,” they said, as sodium nitrite has “many legitimate and necessary uses.”
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