Mushroom poisoning refers to symptoms that can vary from slight gastrointestinal discomfort to death resulting from ingestion of toxic substances present in a mushroom. The toxins present are metabolic byproducts produced by the fungus. Typically, mushroom poisoning is the result of a gatherer of wild mushrooms mistakenly identifying a toxic mushroom as a non-toxic or edible species. Because some edible and poisonous fungi have very similar appearances, mistakes are usually the result of misidentification based on superficial characteristics. Even very experienced wild mushroom gatherers are sometimes poisoned, despite being well aware of the risks.

No golden rules for safety

There is much folklore providing misleading tips on defining features of poisonous mushrooms, such as:

• Having bright flashy colours. (False: some very toxic species are pure white, such as the destroying angel).
• Lack of snail or insect infestation. (False: while a fungus may be harmless to invertebrates, it could be toxic to humans. The death cap for instance is often perforated by insect larvae).
• Becomes black when touched by silverware or an onion. (False: most mushrooms tend to darken as they wither).
• Poisonous mushrooms smell and taste horrible. (False: some poisonous mushrooms actually taste delicious, according to victims, and one brave person reportedly once cooked a whole meal with the destroying angel mushroom, tasting pieces, whereafter spitting them out; he confirmed that it tasted rather good).
• Any mushroom becomes safe if cooked enough. (False: the chemical structure of some toxins is very stable, even at high temperature).

In reality, there are no simple guidelines to identify poisonous mushrooms. The only completely foolproof rule for preventing mushroom poisoning is of course abstinence — it's better to be safe than sorry. A common rule followed by mushroom hunters is "when in doubt, throw it out". In general, being experienced, having both taxonomic and distributional knowledge, and not taking chances is the only way of minimizing the obvious risk. Actually, even this could be insufficient as mushrooms are sometimes contaminated by concentrating pollutants, like heavy metals and radiation (see Chernobyl disaster effects). Some academic mycologists in fact do not eat wild mushrooms, despite their professional knowledge, and very knowledgeable collectors are sometimes poisoned.

Persons who gather wild mushrooms should follow some practical guidelines (see mushroom hunting). In particular, they should not:

• eat any mushroom they cannot positively identify;
• allow small children to gather mushrooms for consumption;
• mix known edibles with questionable species while gathering, since parts may break off and intermix. A single poisonous mushroom can poison an entire basket.

In addition:

• all wild mushrooms must be thoroughly cooked before eating;
• alcohol consumption should be limited when eating previously untried wild mushrooms since some species, most notably ink caps (Coprinus) can cause an adverse reaction (good mushroom books document this reaction for the species involved, and remember that you must always know what species you are eating -- but caution is still advised for any mushroom species tried for the first time);
• when anyone tries a species that he or she has not eaten previously, portions should be kept small: no more than 150 grams per person at one sitting.

An experienced mycologist or mushroom picker will know which mushrooms have dangerous look-a-likes that might cause confusion resulting in an accidental poisoning. In Europe, especially in forested regions, many people have local knowledge of one or two fungi that have been picked and eaten for generations and used in the regional cuisine. In Italy and France, for instance, several species of porcini (Italian name; cèpe in French) have been picked and enjoyed at least since Roman times. These are members of the genus Boletus, which can be identified in part by the fact that they have pores rather than gills, species for which few common lethal look-alikes exist. In some regions in Europe, mushrooms are not eaten at all; in other regions, such as Finland, Scandinavia and Russia, which traditionally have suffered from food shortage in winters, strong local knowledge on edible mushrooms exist and mushrooms form a remarkable part of cuisine. Yet many mushroom enthusiasts limit their pickings only on easily recognizable mushrooms, such as chanterels and boletes, and leave agarics unpicked. False morel is often called the "fugu of the Finnish cuisine", and not without reason; it is deadly poisonous when raw, but delicious if properly prepared.

As mentioned, however, specimens looking similar to known edibles at home may be deadly in another place and should not be collected without good local knowledge of the biota. For instance, the tasty Cantharellus is enjoyed by many people in Scandinavia where no risk of confusing this mushroom with deadly species exists. However, in North America, this ground-dwelling mushroom has been known to be mistaken for the wood-decaying Jack O' Lantern mushroom (Omphalotus illudens), which may indeed seem to grow from the ground if there is buried wood present. Note also recent reports of confusion between Volvariella speciosa, a popular edible species in Asia, and Amanita phalloides, a deadly poisonous species in North America.

Another common problem derives from the fact that developing (newly formed) destroying angel mushrooms very much resemble the well-known champignon, or button mushroom (the mushroom widely sold in markets and used on pizzas). Similarities between these species lead to a few deaths every year in Scandinavia alone.

Recommendations that one should follow:

• Know the characteristics (shape, color, growing terrain, etc.) of all the toxic mushrooms growing in the area. In Europe and North America, these include the deadly Amanita phalloides and Amanita virosa, as well as the non-lethal Amanita pantherina and Amanita muscaria; but this list is not exhaustive, and any unknown mushroom must be treated as dangerous.
• Stick to collecting mushroom species you know and that have no risk of being confused with toxic species.

Poisoning by Amanita phalloides (the death cap) is characterised by a delay of between 6 and 24 hours from the time of ingestion to the onset of symptoms. During this time, the cells of the kidneys and liver are attacked. There is no antidote for poisoning by A. phalloides, and mortality is between 50 and 90 percent.

Symptoms

Serious symptoms do not always occur immediately after eating; often not until the toxin attacks the kidney, from minutes to hours later. In rare cases, symptoms leading to death may not appear for days after eating a poisonous mushroom. Symptoms typically include:

• Lethargy
• Headache
• Dizziness
• Cold sweat
• Vomiting
• Sharp abdominal pains
• Jaundice
• Severe diarrhea

If treated promptly, death can usually be avoided. Otherwise, with some toxins, death could result within a week or a few days, if the species ingested is a potent one.

Poisonous species

Three of the most lethal mushrooms belong to the genus Amanita: the death cap (A. phalloides) and destroying angels (A. virosa, and A. verna); and two are from the genus Cortinarius: the deadly webcap (C. rubellus), and the fool's webcap (C. orellanus). These species cause the greatest number of fatalities. The principal toxins are alpha-amanitin in the genus Amanita and orellanine in the genus Cortinarius.

The following species may cause great discomfort, but are less often lethal.

• Amanita muscaria (fly agaric) – poisonings rare, possibly because its unique and obvious appearance make it easily identifiable; however, its long history of use as an entheogen and new reports suggesting it is less toxic than once thought may suggest otherwise.
• Amanita pantherina (panther mushroom) – Contains similar toxins as A. muscaria, but in higher quantities; first signs of distress occur after 8 to 12 hours; 80–85% of victims survive.
• Amanita regalis – symptoms generally mild
• Entoloma spp. – highly poisonous, such as livid Entoloma (Entoloma sinuatum), Entoloma rhodopolium, and Entoloma nidorosum. First symptoms appear after 20 minutes to 4 hours.
• Galerina – Some species contain alpha-amanitin (deadly poisonous)
• Many Inocybe spp. – Inocybe fastigiata, Inocybe geophylla, and Inocybe patouillardii
• Some white Clitocybe – First symptoms after 15 to 20 minutes
• Tiger Tricholoma – no lasting effect after 2 to 6 hours of great pain.
• Sulfur tuft – poisoning may be serious
• Omphalotus olearius – mild
• False morel (Gyromitra esculenta) – may not affect some people at all. Deadly poisonous when raw; harmless and delicious if correctly prepared.
• Brown roll-rim – once thought edible, but now found to be destructive of red blood cells with regular or long-term consumption.
• Devil's Boletus (Boletus satanas)
• Purple Boletus (B. rhodoxanthus)
• Coprinus atramentarius
• Conocybe filaris contains amatoxins, sometimes thought to be a Psilocybe.

External links

• Mushroom toxins from the Center for Food Safety & Applied Nutrition

• Poisonous mushrooms: microscopic identification in cooked specimens from medical mycologist R.C. Summerbell

Mushrooms | Toxicology | Mycotoxins | Otrava houbami | Pilzvergiftung | Avvelenamento da funghi | Nuodingieji grybai