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With foraging becoming more and more popular, health experts around the globe are sounding an alarm: beware the appropriately named death cap mushrooms and other potentially lethal fungi.
In Canada, researchers have warned that the death cap, called Amanita phalloides—the world’s most poisonous mushroom —is expanding its range in British Columbia and has the potential to spread throughout the continent.
A study published in the latest issue of the B.C. Medical Journal urged people to familiarize themselves with the risks associated with consuming wild mushrooms and with the symptoms of poisoning.
Australia’s Food Safety Information Council Australia recently advised people not to pick or eat wild mushrooms in certain parts of the country, including Melbourne and rural Victoria.
Death cap mushrooms, which contain a toxic compound called amatoxin, are said to be responsible for 90 percent of all mushroom fatalities worldwide.
Death caps can easily be mistaken for an edible species of mushroom, as seen in three cases in B.C., one fatal, among people who misidentified them, according to the BCMJ study.
A three-year-old boy died after consuming a death cap foraged from a residential street in Victoria in 2016. In 2008, a 63-year-old woman in Vancouver was hospitalized after she consumed a death cap that she assumed was a paddy straw mushroom, and a 43-year-old man in Victoria was hospitalized in 2003 after ingesting a death cap he thought was a puffball mushroom.
“Do not eat things you have not identified with certainty as being safe,” says Paul Kroeger, a consultant for the B.C. Drug and Poison Information Centre and a founding member and past president of the Vancouver Mycological Society.
He says people may have a false perception of safety when it comes to death caps because they grow predominantly in urban areas and don’t necessarily “look” dangerous.
“I advise people not to eat things just because they’re growing around their home,” Kroeger says. “A surprising number of people will actually eat something because it grew in their yard.
“The death cap is surprisingly innocuous looking, even attractive looking; it has a clean, whitish appearance,” he says. “It doesn’t have the flashy colours that people assume are poisonous.”
Take the Amanita muscaria, commonly known as toadstool, with its red cap and white dots, which often appears in children’s books and fairy tales: “It’s not dangerous; it’s mildly poisonous, but people don’t really get attracted to eating it because it looks like it might be,” Kroeger says. “A death cap just doesn’t look very scary and very dangerous.”
The amatoxin in death caps, which is not rendered harmless by cooking, freezing, or drying, attacks the liver and kidneys.
Symptoms of poisoning appear in three phases. Six to 24 hours after ingestion, people experience severe abdominal pain, vomiting, and “cholera-like” diarrhea that may contain blood and mucus and often results in profound dehydration, according to the BCMJ.
Next is a “false recovery” phase; 24 to 72 hours after ingestion, people start to feel a bit better.
The third phase, which takes place four to nine days after eating the mushroom, is characterized by acute liver and multisystem organ failure that can lead to convulsions, hemorrhage, coma and death.
There is no antidote, and if acute liver failure occurs, the only potential cure is organ transplantation.
While death cap mushrooms might not exist in other provinces—yet—there are several other types of mushrooms in Canada that can cause serious poisoning or death.
One is the white or whitish Amanita smithiana, which people often mistake for the highly desired pine mushroom or its Japanese relative, the matsutake.
“About every year somebody will mistake the Amanita smithiana for the pine mushroom, resulting in severe kidney damage, and they have to be maintained on dialysis until recovery, which can often be a month or more,” Kroeger says. “It’s not yet proven to be fatal, but it’s proven to be extremely debilitating.”
Lepiota subincarnata is another. The small mushrooms are common in landscaped areas and lawns. The Vancouver Mycological Society describes them as extremely dangerous and potentially deadly, containing toxins that damage or destroy the liver and kidneys.
A 56-year-old man in New Westminster, B.C. died in 1998 after eating Lepiota subincarnata picked from his lawn in a breakfast omelette, believing they were fairy-ring mushrooms, according to the Vancouver Mycological Society. He began to experience abdominal pain, severe vomiting, and leg cramps 13 hours later. The next day he was admitted to hospital, where, two days after ingestion, he began to feel better even though tests indicated that liver damage was occurring. The following day, he had nausea, abdominal pain, vomiting, and diarrhea. He went on to lose consciousness and was placed on life support after liver and kidney failure, and passed away nine days after eating the mushrooms.
Of concern to experts like Kroeger is the increasing interest in the potential health benefits of certain mushrooms, which could encourage more people to seek out mushrooms on their own without properly identifying them. Psylocybin mushrooms, for instance, are being studied for the role they could play in treating mental-health conditions. Psilocybin is a hallucinogen that has similar properties to lysergic acid diethylamide (LSD) and mescaline.
“With increasing access to mushrooms and a lot of press about the positive aspects of them, they’ve begun to circulate in the black market,” Kroeger says. “We do not have a tracking system for their provenance, and there’s no surety that the person supplying them is ethical knowledgeable.
“My piece of advice is stick with only very distinctive, very familiar, well-known edible species,” he says. “My advice is not to be adventurous.”