My watch list
my.bionity.com  
Login  

Mushroom poisoning



See also: List of deadly fungi
Mushroom poisoning
Classification & 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 metabolic byproducts produced by the fungus. Mushroom poisoning is generally the result of an eater of wild mushrooms mistakenly identifying a toxic mushroom as a non-toxic or edible species. Because some poisonous fungi closely resemble commonly eaten species, mistakes may arise from misidentification based on superficial characteristics. Even very experienced wild mushroom gatherers are sometimes poisoned by eating toxic species, despite being well aware of the risks.

The safest way to avoid being poisoned is to learn species intended for picking and those to avoid.

Additional recommended knowledge

Contents

Folklore

There are many folkloric stories on defining features of poisonous mushrooms[citation needed], such as:

  • Having bright flashy colours. (False: although some very toxic species are brightly coloured, others such as the destroying angel are pure white).
  • 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 taste delicious, according to victims).
  • Any mushroom becomes safe if cooked enough. (False: the chemical structure of some toxins is very stable, even at high temperature. Therefore, heat will not reliably destroy toxins).
  • A mushroom which has a cap which can be peeled is edible. (False: the death cap falls in this category).

As can be seen, folkloric stories are deceptive and therefore cannot be used as a reliable means of identification.

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;
  • allow small children to gather mushrooms for consumption;
  • mix known edibles with questionable species while gathering, since parts could break off and intermix.

In addition:

  • cooking mushrooms before eating is safer;
  • alcohol consumption should be limited when eating previously untried wild mushrooms since some species, most notably certain ink caps (Coprinopsis atramentaria) 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-alikes 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 poisonous 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 exists and mushrooms form a remarkable part of cuisine. Yet many mushroom enthusiasts limit their pickings only on 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", and not without reason; it is deadly poisonous when raw, but rarely causes trouble if properly prepared -- though it is nonetheless considered highly toxic and its use as food is definitely not recommended by mycologists.

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 toxic 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 olearius), 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 and Europe.

Another common problem derives from the fact that developing (newly formed) destroying angel (Amanita virosa) 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 decade in Scandinavia alone.

In contrast to the commonness of mushroom poisoning fatalities in Europe, such cases are far less common in North America; this may very well be directly related to the use of unwritten folk knowledge in Europe, whereas North American mushroom hunters who gather numerous species tend to refer often to authoritative reference works.

Poisoning by Amanita phalloides (the death cap) 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 by A. phalloides, and mortality is between 10 and 15 percent.[1] There have been some recorded studies regarding Silybum marianum or blessed milk thistle protecting the liver from aminita toxins and promoting regrowth of damaged cells, including a study whereby 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.[2]

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:

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.

Toxins

See also Category:Mycotoxins.

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. The principal toxins are alpha-amanitin in the genus Amanita and orellanine in the genus Cortinarius. Many species of Galerina, Lepiota, and Conocybe contain lethal amounts of amatoxins.

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; it is known for its use as an entheogen, and it is now known that the toxins convert to psychoactives upon drying.
  • Amanita pantherina (panther mushroom) – Contains similar toxins as A. muscaria, but in higher quantities.
  • Amanita muscaria var. regalis – symptoms generally mild.
  • Chlorophyllum molybdites (greengills) - causes intense GI upset
  • Entoloma (pinkgills) – 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. such as Inocybe fastigiata and Inocybe geophylla contain muscarine, while Inocybe patouillardii is the only one known to have caused death.
  • Some white Clitocybe, including C. rivulosa and C. dealbata; First symptoms after 15 to 20 minutes
  • Tiger Tricholoma (Tricholoma tigrinum) – no lasting effect after 2 to 6 hours of great pain.
  • Man-on-horseback Tricholoma equestre, until recently thought edible and good, can lead to rhabdomyolysis after repeated consumption.
  • Sulfur tuft (Hypholoma fasciculare) – poisoning may be serious
  • Omphalotus olearius – severe
  • False morel (Gyromitra esculenta) – Deadly poisonous when raw; usually ok cooked, delicious if correctly prepared.
  • Brown roll-rim (Paxillus involutus) – once thought edible, but now found to be destructive of red blood cells with regular or long-term consumption.
  • Devil's bolete (Boletus satanas)
  • Purple bolete (B. rhodoxanthus)
  • Conocybe filaris contains amatoxins, sometimes mistaken for Psilocybe.
  • Some species of Agrocybe contain a deadly amount of toxins.
  • Hebeloma crustuliniforme, commonly known as Poison pie or Fairy cakes, can cause gastrointestinal symptoms such as nausea and vomiting.

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.

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


Famous Poisonings

  • Roman Emperor Claudius is said to have been murdered by being fed the death cap mushroom.
  • Holy Roman Emperor Charles VI, Pope Clement VII, and Tsaritsa Natalia Naryshkina

are believed to died from eating the death Cap mushroom.

References

  1. ^ 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. 
  2. ^ Blake V. "Milk thistle": 706-707. in: (2004) PDR For Herbal Medicines. New York: Thomson Healthcare. 
  • Mushroom toxins from the Center for Food Safety & Applied Nutrition
  • Poisonous mushrooms: microscopic identification in cooked specimens from medical mycologist R.C. Summerbell


 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Mushroom_poisoning". A list of authors is available in Wikipedia.
Your browser is not current. Microsoft Internet Explorer 6.0 does not support some functions on Chemie.DE