Mushroom poisoning

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See also: List of deadly fungi
Mushroom poisoning
Classification and external resources
These emerging mushrooms are too immature to safely identify as edible or toxic.
ICD-10 T62.0
ICD-9 988.1
MeSH D009145

Mushroom poisoning, also known as mycetism, refers to deleterious effects from ingestion of toxic substances present in a mushroom. These symptoms can vary from slight gastrointestinal discomfort to death. The toxins present are secondary metabolites produced in specific biochemical pathways in the fungal cells. Mushroom poisoning is usually the result of ingestion of wild mushrooms after misidentification of a toxic mushroom as an edible species. The most common reason for this misidentification is close resemblance in terms of colour and general morphology of the toxic mushrooms species with edible species. Even very experienced wild mushroom gatherers are sometimes poisoned by eating toxic species, despite being well aware of the risks.

To prevent mushroom poisoning, mushroom gatherers need to be very intimately familiar with the mushrooms they intend to collect, including knowledge of the toxic species that look similar to these edible species. Other considerations regard methods of preparation and toxicity of some fungal species that appears to vary with geographic location, raising the potential of mushroom poisoning due to local toxicity of a correctly identified species.

Contents

[edit] Folk traditions

There are many folk traditions concerning the defining features of poisonous mushrooms[1][2]. Unfortunately there are no general identifiers for poisonous mushrooms, and so such traditions are unreliable guides. For example, while some highly coloured mushrooms such as fly agaric are indeed poisonous, other strongly coloured mushrooms are harmless. Other highly toxic mushrooms, such as the appropriately named destroying angel, are of unremarkable white colour. Lack of snail or insect infestation is also an unreliable identifier, since fungi that are harmless to invertebrates can still be toxic to humans; the death cap, for instance, is often infested by insect larvae. Likewise, poisonous mushrooms neither blacken silverware during cooking, nor necessarily smell or taste unpleasant. Importantly, many fungal toxins are not particularly sensitive to heat and so are not broken down during cooking.

[edit] Guidelines

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; not allow small children to gather mushrooms for consumption; or mix known edibles with questionable species while gathering, since mushroom parts could break off and be confused with edible species.

Cooking mushrooms before eating is a safer practice, as only very few species can be eaten raw. Alcohol consumption should be limited when eating wild mushrooms positively identified as edible, but not consumed before[citation needed]. Some species, most notably certain ink caps (Coprinopsis atramentaria) can cause an adverse reaction when eaten with alcohol. Portions of species that a person has not eaten before should be kept small (no more than 150 grams per person at one meal[citation needed]).

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 exists and mushrooms form a remarkable part of cuisine. Yet many mushroom enthusiasts limit their pickings to only easily recognizable mushrooms, such as chanterelles and boletes, and leave agarics unpicked. False morel (Gyromitra esculenta) is often called the "fugu of the Finnish cuisine", since it is deadly poisonous when raw, but rarely causes poisoning if properly prepared (although its edibility is still a matter of dispute).

Specimens that look similar to edibles at one geographic location may be deadly in another region and should not be collected without good knowledge of the local biota. For instance, Cantharellus is often picked in Scandinavia where no risk of confusing this mushroom with toxic species exists.[citation needed] However, in North America, this ground-dwelling mushroom has been known to be mistaken for the wood-decaying Jack O'Lantern mushroom (Omphalotus olearius), which may 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 and Europe.

Very young fruiting bodies of destroying angel (Amanita virosa) mushrooms resemble the well-known champignon, or button mushroom, a mushroom widely sold in markets. Similarities between these two species lead to a few deaths every decade in Scandinavia alone[citation needed].

Cases of fatal mushroom poisoning are relatively common in Europe, but less so in North America ;[citation needed] this may be related to the use of folklore rather than detailed knowledge in Europe, whereas North American mushroom collectors tend to refer often to authoritative reference works.[citation needed][original research?]

[edit] Symptoms

Poisonous mushrooms contain a variety of different toxins that can differ markedly in toxicity (see list below). So symptoms of mushroom poisoning may vary from gastric upset to life-threatening organ failure resulting in death. Serious symptoms do not always occur immediately after eating; often not until the toxin attacks the kidney or liver, from minutes to hours later, or, as is the case for α-amanitin poisoning, not until days after consumption. Symptoms may not appear for days and thus delay lifesaving treatment.

Symptoms of mushroom poisoning vary depending on the toxins involved and typically include:

Some mushrooms contain less toxic compounds and, therefore, are not severely poisonous. Poisonings by these mushrooms may respond well to treatment. However, certain types of mushrooms, such as the Amanitas, contain very potent toxins and are very poisonous; so even if symptoms are treated promptly mortality is high. With some toxins, death can occur in a week or a few days. Although a liver or kidney transplant may save some patients with complete organ failure, in many cases there are no organs available. Patients who are hospitalized and given aggressive support therapy almost immediately after ingestion of amanitin-containing mushrooms have a mortality rate of only 10%, whereas those admitted 60 or more hours after ingestion have a 50-90% mortality rate (http://www.cfsan.fda.gov/~mow/table2.html) and (http://vm.cfsan.fda.gov/~mow/Chap40.html)

More detail on the exact symptoms associated with different toxins can be found below.

[edit] Toxins

See also: Category:Mycotoxins.

[edit] Poisonous species

See also: List of deadly fungi

Three of the most lethal mushrooms belong to the genus Amanita: the death cap (A. phalloides) and destroying angels (A. virosa, and A. bisporiga); 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. Poisoning by Amanita phalloides is characterized 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 and mortality is between 10 and 15 percent.[3] There have been some recorded studies suggesting that Silybum marianum or blessed milk thistle protect the liver from aminita toxins and promote regrowth of damaged cells, including a study in which 60 patients exposed to death cap poison were given 20 mg/kg of milk thistle seeds per day within 48 hours of consuming the deadly mushrooms. None of the patients died.[4]

Many species of Galerina, Lepiota, and Conocybe contain also lethal amounts of amatoxins.

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

[edit] Other causes of poisoning

Mushrooms may be rendered poisonous by insecticides or herbicides sprayed on lawns or reserves. At least one author recommends never picking them in non-natural landscapes for this reason.[citation needed]

Also, mushrooms are sometimes contaminated by concentrating pollutants, such as heavy metals or radioactive material (see Chernobyl disaster effects).

[edit] Famous poisonings

[edit] References

  1. ^ California Poison Action Line: Mushrooms. Retrieved on 2008-02-18.
  2. ^ Ian Robert Hall (2003). Edible and Poisonous Mushrooms of the World. Timber Press, p. 103. ISBN 0881925861. 
  3. ^ Benjamin DR. "Amatoxin syndrome": 198–214.  in: (1995) Mushrooms: poisons and panaceas — a handbook for naturalists, mycologists and physicians. New York: WH Freeman and Company. 
  4. ^ Blake V. "Milk thistle": 706-707.  in: (2004) PDR For Herbal Medicines. New York: Thomson Healthcare. 
  5. ^ V J Marmion and T E J Wiedemann (2002). "The death of Claudius". Journal of the Royal Society of Medicine 95: 260-261. 

[edit] External links

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