Wild Mushroom Safety

by Food and Drug Administration (FDA)

Mushrooms can kill you, the Frenchman told author Peter Mayle, newly transplanted to Provence from England.

"That I could believe," Mayle wrote in A Year in Provence, but it didn't explain the thigh-high rubber boot the Provenáal wore on his right leg, or the man's nervous thrusting of a stick around the roots of an old scrub oak tree "in the manner of a fencer expecting a sudden and violent riposte."

"This was a new and worrying aspect of the Lubçron," Mayle wrote. "It was, as I already knew, a region full of strange things and even stranger people. But surely mushrooms, even wild mushrooms, didn't attack fully grown men."

Poisonous mushrooms can wreak havoc on men, women and children. If ingested, their toxins can cause stomach upset, dizziness, hallucinations, and other neurological symptoms. The more lethal species can cause liver and kidney failure, coma, and even death.

As it happens, the Provenáal's immediate concern was not poison: "He slapped the rubber [boot] with his wooden sword and swaggered down toward me. D'Artagnan with a shopping basket ... 'Les serpents.' He said it with just the trace of a hiss. 'They are preparing for winter. If you disturb them — ssst! — they attack. It can be very grave.'"

Here in the United States, Food and Drug Administration biologist John Gecan worries less about "les serpents" than about ignorance when it comes to harvesting wild mushrooms. Many edible mushrooms have toxic "look-alike" species, Gecan says, and untrained pickers often are woefully incompetent to distinguish the bad from the good.

The Unskilled

"People go out and harvest wild mushrooms without the foggiest notion of what they're picking. They may know what mushrooms they're looking for, but they may also mistakenly pick up toxic look-alikes found in the same place," he says.

Gecan, a mushroom expert with the agency's Center for Food Safety and Applied Nutrition, says quite simply: "As a novice, you'd better not go out and pick mushrooms, eat them, and expect to live very long."

FDA regulates commercially grown and harvested mushrooms, which are cultivated in concrete buildings or caves, but there are no systematic controls on individual gatherers harvesting wild species.

Some of the most deadly mushrooms produce toxic amanitins. Among them is the genus Amanita, whose members have telltale common names such as death angel, fool's mushroom, and destroying angel. These, and less deadly species, may end up in gourmet shops, co- ops, supermarkets, and restaurants, mistaken for their nontoxic, edible look-alikes.

Armed with illustrated books and a big jar of dried mixed forest mushrooms imported from France, Gecan demonstrates how difficult it can be to distinguish similar looking species. He emphasizes that even experts can't know all there is to know to identify every kind of wild mushroom, because of their great diversity.

There are two general groups of fleshy fungi — ascomycetes and basidiomycetes — which are differentiated by their spore-bearing reproductive structures. Ascomycetes bear spores enclosed in a sac- like cell called an ascus. They include the cup fungi, false morels, and true morels. Basidiomycetes bear spores on one end of a specialized cell called a basidium. This group is further broken down into subgroups based on their spore-bearing structures and include, among others, the chanterelles, gilled fungi (including the "button" mushrooms commonly seen in supermarkets), and puffballs.

Gecan, whose primary expertise is identifying morels and their look-alikes, illustrates the complexity of the task. He notes, for example, that the edible bell morel Verpa conica and half-free morel Morchella semilibera, and the poisonous early "false morel" Verpa bohemica all have caps that look like a partially closed parasol with vertical ridges and striations. The three can easily be confused by an inexperienced harvester, as their distinguishing features are not conspicuous.

The edible half-free and bell morels both have eight spores per ascus, but the stem on the half-free attaches halfway up inside the cap, while the stem of the bell morel attaches at the very top of the cap. The stem of the poisonous early false morel also attaches at the very top of the cap, but it has only two to four large spores per ascus.

The Unscrupulous

Unskilled harvesters are not the only problem of the wild mushroom trade; the lucrative market has generated its share of unsavory characters.

"There's such an economic gain to be had here that people are going out knowingly including the toxic Verpa bohemica in their harvest of edible morels. This was a serious contamination problem in morels coming from India in the late 1980s," Gecan says. He tells of an importer who admitted that some harvesters will pick up anything that looks like a morel, adding that some pickers even stuff them with stones to increase the weight.

The wild mushroom business has also spawned violence. Some wild mushrooms sell for $100 or more a pound, Gecan says, and armed robberies are occurring in the Pacific Northwest, where the combination of heavy-covered forests and moist environment yields a plentiful crop.

The Evidence

FDA first became involved with analyzing wild mushrooms when agency field inspectors sent samples to headquarters laboratories following a poisoning outbreak in 1977. Four people suffered abdominal pains, dizziness, vomiting, and fainting after eating "veal morel" at a New York City restaurant. The morels, imported from France and Switzerland, included Gyromitra esculenta mushrooms, which produce the methylhydrazine derivative gyromitrin, a toxin that can sometimes cause death. "It's basically one of the components of rocket fuel," Gecan says.

He explains that "Gyromitra is picked and canned and eaten in France and elsewhere in Europe with no ill effects, because the chefs over there know how to prepare them."

In July 1978, FDA issued an import alert directing sampling of morel shipments from the French and Swiss firms implicated in the 1977 outbreak. In 1980, analysis of samples of French morels collected by FDA's Denver district showed they contained Gyromitra.

About the Author

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FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.