Lect18: Poisonous Mushrooms

Poisonous Mushrooms

Introduction

We have briefly discussed mushroom toxins when we covered entheogenic mushrooms. It was summarized at that time that poisonous mushrooms may have a variety of mycotoxins that may be divided into classes, according to their chemical structures. This is a topic of interest because mushrooms have been gathered for eating throughout the world, for thousands of years, and during that time many people have become ill or died when they inadvertently consumed poisonous mushrooms. While the mushrooms that are poisonous in a given area are generally well known, fatal mushroom poisoning may still occur.

The knowledge as to whether mushrooms are poisonous or edible is important for those who wish to go out to collect mushrooms for the purpose of eating them. With a little common sense, it is something that can be fun to do, either by yourself or as a group activity. There are, in fact, many amateur mushroom societies throughout the country that were formed for the purpose of going out to collect mushrooms and eating what they have collected at the end of the day. There are many edible mushrooms that can be found that are good to eat that are very distinct and will not be mistaken for poisonous species. If the collector sticks to those species, there should not be any problems. The most common reason for the occurrence of mushroom poisoning is collecting and eating a species of mushroom that closely resembles one that is poisonous. This is probably the most common cause of mushroom poisoning.

A question that is often asked by the novice mushroom collector is how can you determine if a mushroom is poisonous or not. Often the poisonous species is referred to as a "toadstool", but in terms of the general appearance of poisonous mushrooms do not look any different than those that are edible. The toadstool label is just a means by which some people refer to poisonous mushrooms. There are no generalizations that can be made that will allow you to distinguish between what is edible and what is not. "Fool-proof" means of making this distinction are myths and are untrue. Some of the most common example is that a silver coin will turn black when cooked with a poisonous mushroom, if animals are seen eating the mushroom, then it is not poisonous, if the top layer of the cap can be peeled, it is not poisonous and there are more. The only means by which species have been determined to be poisonous is if somebody had eaten it and got sick and/or died.

Mushroom Poisoning, True and Fictional Stories

There are numerous stories about mushroom poisonings. Many are fictional, murder mysteries, such as Dorothy Bowers, Postscript to Poison, Agatha Christie's 4:50 From Paddington and Ariana Franklin’s The Serpent’s Tale. However, these novels and most other do not mention what mushroom was eaten, probably because the authors did not feel it important enough to do so. One exception is one by Dorothy Sayers and Robert Eustace, The Documents in the Case. Amanita muscaria was specifically named in this novel because of its significance in the story. In this novel, George Harrison is found dead, apparently from mushroom poisoning, having mistaken the edible Amanita rubescens with A. muscaria. However, his son Paul believes otherwise. His father's hobby was foraging for mushrooms and was an expert on the identification of wild mushrooms. His son would eventually be proven correct. His father was in fact poisoned by his step mother and lover by lacing the A. rubescens with a synthesized form of the mushroom toxin muscarine. That the muscarine was synthetic was demonstrated by the fact that polarized light "rotates" when passed through the synthetic toxin while the natural toxin would not. However, the story is now dated. Although Muscarine was thought to be a toxin in A. muscaria, when this novel was written in 1930, as can be surmised by its name, we now know that this toxin does not occur in this species.

While there are novels where mushrooms are the poison of choice in the stories, there are many instances where true stories of mushroom poisoning may sound like their fictional counter parts. In 1918, a Frenchman by the name of Girard, was tried and convicted of multiple murders, all involving poisons. Some of these included using the Death Cap, Amanita phalloides. With either his wife or mistress, Girard would make friends with other couples or individuals who were approximately their same age. They would then take out an insurance policy posing as the couple or individuals, naming themselves as the beneficiary of the insurance policy. Once the policy was taken out, the couple or individual was then invited to dinner where they were poisoned. However, they became too greedy with one of his victims. They had taken out four different insurance policies on one woman and had collected the insurance money from three of the companies without incident. The fourth company, however, had a suspicious physician who questioned why such a young and healthy woman would suddenly die. When the doctor decided to perform an autopsy to determine the cause of death, he saw that the body was not the woman that he had examined earlier when the insurance policy was taken out. Further investigation revealed the trail of murders that Girard and his accomplices had carried out. Girard was sentence to death, but died of tuberculosis before his execution was carried out. His two accomplices, his wife and mistress were sentenced to life.

One of the most famous of all planned murders was that of Emperor Claudius by his fourth wife, Agrippina, The Younger, who was also his niece! The story behind this assassination, as well as the political intrigue that was present during this period of the Roman Empire could readily have been made into a popular mini series and/or soap opera. Claudius became emperor, in 41 A.D., following the assassination of his nephew Caligula, and married Agrippina, his fourth wife, after disposing of Messalina, his third wife, for adultery. Agrippina came into the marriage with Nero, a son from a previous marriage and wanted him to follow Claudius as emperor. Agrippina persuaded him to adopt her son so that Nero would be in line to become emperor. In order to hasten Nero's ascend to the throne, Agrippina planned Claudius' death by preparing his favorite mushroom, Amanita caesarea (Fig. 3), which was also a favorite of the Roman nobility. However, the dish of mushroom was laced with the juice of A. phalloides, by Locusta, Claudius' trusted, or so he thought, servant. Claudius became very ill and his personal physician Xenophon was called in, who turned out to be another of the conspirators to the crime. Because the A. phalloides did not kill Claudius quickly enough, Xenophon gave him an enema that had a massive dose of colocynth, a toxic alkaloid derived from Bitter Apple, Citrullus colocynthis. Following the death of Claudius, Nero became emperor of Rome.

A recent case of mushroom occasion involving the Nicholas Evans, the well known author of the Horse Whisperer, his wife, his brother-in-law and his wife were all hospitalized the day after eating a meal in which the poisonous Cortinarius speciosisimus (Fig. 4) was mistaken for the edible Boletus edulis (Fig. 5). As a result of ingesting C. speciosisimus, renal failure occurred in both men, who must undergo regular renal dialysis and are awaiting kidney transplants, when the organs become available. Evans' wife will also require a transplant in the future. Only his brother-in-laws wife will not require a transplant because she had not eaten much of the evening's meal. Unfortunately, such cases of mistaken identity are all too common, even among mushroom foragers, such as Evans, who has picked mushrooms for many years.

Mushroom Toxins and Their Symptoms

It seemed like almost every year, when I lived in California, since I became interested in mushrooms, somebody would inevitably die from mushroom poisoning. The reason for this is not because every other species of mushroom is poisonous nor that mushrooms are that difficult to identify. As I have mentioned previously, relatively few mushrooms are poisonous and of those that are, only a handful will be fatal if consumed. We will go over, in detail, the different types of toxins that are known to occur in mushrooms. These toxins are summarized in the table below, with specific examples of the toxins and some fungi that are known to have these toxins.

You may noticed that there is are a number of redundant symptoms, i.e. vomiting, diarrhea and abdominal cramps. Thus, these symptoms are not that useful, but do provide an indicator that some sort of food poisoning has occurred.

Note that in the different groups of toxin, there is not a means of determining that these mushrooms are poisonous and that only by chemical analysis were the different toxins identified.

Group I. Phallotoxins and Amatoxins: This group of toxins is responsible for most fatalities in mushroom poisonings. Fortunately, they occurs in only a few taxa. The most common known species having these toxins belong in the genus Amanita, in the section Phalloideae, and in the genus Galerina. However, it is estimated that over 90% of mushroom fatalities is due to consumption of only one species, Amanita phalloides. Although the latter species does not occur in Hawai‘i, we do have a common species, Amanita marmorata, which belongs in the same section of the genus. Although there have not been any incidents of human fatalities, there have been several documented cases where pets have died as a result of consuming this species. This species forms mycorrhizae and is associated with trees belonging to the genus Casuarina (Iron Wood), Eucalyptus and Melaleuca (Paper Bark). This association does not mean that the mushrooms are necessarily growing directly at the base of these trees. The mushrooms are usually associated with the root tips of the trees. Thus, they may be some distance away from the tree!

The toxins involved are complex polypeptides. It was once believed that both the phallotoxins and amatoxins contributed in poisoning the consumer, but apparently only the latter is responsible. When phallotoxins are directly injected into mice, they are up to ten times more lethal than cyanide. However, when taken orally, phallotoxins have no effect. Thus, it is only the amatoxins, which is lethal, when mushrooms with Group I toxins are consumed.

In cases where A. phalloides has been consumed, the victims described the taste as mild to quite good, which is probably why large amounts of it is normally consumed. The amatoxin rapidly attacks the intestine, liver and kidney. However, any discomfort from this toxin is not immediate. It may be as long as 24 hours before any symptoms occur. This in itself makes treatment of the toxins difficult since the victim often will not connect the sudden illness with the consumption of mushrooms even if they should seek medical help. During this period of time the toxins are already acting upon the cells of the liver, kidney and intestine. The victim will experience diarrhea, profuse vomiting and abdominal pains, which usually last from four to six days. These symptoms will then subside and the the victim will feel better and will often believe that whatever caused the illness has passed. However, this is misleading. Because by this time, the amatoxins will have caused collapse of kidney and liver function. The victim will then eventually go into a coma and death usually follows. Even when death does not occur, the illness lasts several weeks and permanent damage to the liver and kidney is likely.

At this time, there is still not an accepted method by which amatoxin poisoning can be treated once it has been in the victim's system for more than several hours. By the time the symptoms manifest themselves and the victim seeks medical help, massive damage to the kidney and liver has already been done. Thus, if an unknown mushroom has been consumed, it is best to arrive at a correct identification of that mushroom, immediately. Fortunately, amatoxin poisoning is rare in the United States, but because it is rare, many doctors do not connect these symptoms with mushroom poisoning unless their patients mention it first, and often are not experienced in the identification of mushrooms or the effects of their toxins. Normally, a mycologist is consulted for the identification of the mushroom. If a species containing amatoxins is identified rapidly (within an hour or two after consumption), before it can cause any damage, vomiting is induced in the patient to empty the stomach followed by washing out the stomach.

Group II. Gyromitrin: For many year helvellic acid was assumed to be the cause of blood poisoning. However, we now know that the helvellic acid is harmless. Instead a compound called monomethylhydrazine (MMH), a product produced from hydrolyzed Gyromitrin, is responsible. MMH is used in rocket fuel and is known to be extremely toxic. The toxin is named for the genus Gyromitra from which it was first isolated. Species of Helvella and Paxina are also known to have this toxin. These genera are not known to occur in Hawai‘i.

This Symptoms of this toxin usually appear approximately 2-12 hours after consumption. MMH causes an initial bloated feelings, followed by nausea, and the usual vomiting, diarrhea and abdominal cramps. Severe headaches and pain may also occur and linger for some time. If more severe poisoning has occurred, i.e., individuals who have eaten large amounts of mushrooms containing Gyromitrin, symptoms of liver toxicity will occur after between 36-48 hours. Jaundice and convulsion may occur, followed by coma and eventually death after 2-7 days. It is estimated that Gyromitra esculenta is responsible for 2-4% of reported mushroom fatalities. There are, however, reports that some consumers of this species have been unaffected, but tolerance of individuals, amount of MMH present in fungus and method of cooking may combine to cause widely varying toxic reactions.

The actions of this toxin is somewhat similar to the cyclopeptides in Group I in that it takes affect at the cellular level and causes liver damage. In addition, it is hemolytic, and toxic to the central nervous system and irritates the gastrointestinal tract. Pryridoxine hydrochloride is administered for poisoning by this toxin.

Group III. Orellanin: Consumption of mushrooms containing this toxin has the longest delayed reaction before the appearance of symptoms. Nausea, vomiting, diarrhea and anorexia present in most patient 12 hours to 3 days after consumption. In cases where poisoning was severe, evidence of renal damage occurs (burning thirst, frequent urination) may not occur until 3-15 days after consumption of mushroom. In mild poisoning cases, symptoms sometimes did not appear until 10-17 days after eating the mushroom.

There is a great deal of variation with respect to the recovery of the poisoned victim. In cases where renal damage has occurred, there may be a period of mild renal failure followed by complete recovery. However, in some cases, renal failure may occur and the victim will require lifelong hemodialysis or a kidney transplant, or in some instances coma, followed by death, will occur.

Species of Cortinarius known to have this toxin belongs to the subgenus Dermocybe. Poisoning from this toxin has so far been restricted to Europe where the species of mushrooms containing orellanin occurs. In Hawai‘i, there is only one species of Cortinarius, C. clelandii. Although it belongs to the subgenus Dermocybe, it is not known if it has Orellanin.

Group IV. Coprine (Antabuse-like): Coprinus atramentarius is the most common species known to contain this toxin. Neither this species nor other Coprinus species with this toxin is known to occur in Hawai‘i. The effects of this toxin is unusual in that the physical symptoms occur only if the mushroom is consumed with alcohol (ethanol). The consumption of the mushroom, alone, is not toxic! Following consumption of both the mushroom and alcohol, symptoms will begin to occur in approximately 30-60 minutes, and may occur at any time up to five days after consumption of the mushroom.

Symptoms include hot flushes of the face and neck, a metallic taste in the mouth, tingling sensations in the limbs, numbness in the hands, palpitations, a throbbing headache, nausea and vomiting. The symptoms will continue as long as there is any alcohol in the victim's stomach. With the exception of treatment to control arrhythmia (irregular heartbeat), recovery is normally spontaneous once the body is rid of the alcohol. This toxin is said to be antabuse-like because Antabuse (disulfiram), is prescribed to discourage alcoholics from drinking alcoholic beverages and has symptoms almost identical to coprine.

Group V. Muscarine: Mushrooms containing this toxin are very nondescript and are often referred to as little white or brown mushrooms. Normally, they are found in grassy areas and belong to two common genera, Clitocybe and Inocybe. The former is rare and the latter does not occur in Hawai‘i. Thus, the occurrence of poisoning from these mushrooms is unlikely.

Symptoms begin approximately 30 minutes to 2 hours after consumption of toxin. The toxin stimulates the exocrine glands where sweat, saliva and tears are produced and causes what is referred to as PSL (Perspiration, Salivation, Lachrimation) syndrome. Other symptoms include constriction of pupils, blurred vision, muscle spasms, diarrhea, slow heart-beat and a drop in blood pressure. Although rare, death has been known to occur when the victim's heart stops. However, when this has occurred, the victim usually has had a history of cardiovascular disease. The accepted treatment is intravenous injection of atropine.

Group VI. Muscimol and ibotenic acid: Onset of symptoms in this group may occur 30-120 minutes after consumptions. The toxins acts on the central nervous system causing the victims to suffer from symptoms similar to alcohol intoxication. Toxin affects the central nervous system are compared to alcohol intoxication. Onset of symptoms usually occurs between 30-120 minutes. These symptoms include nausea and vomiting, inability to walk or walking only with a drunken gait, alternation between being uncontrollably active and difficult to rouse, followed by a deep sleep with dreams, lasting about two hours. When large amounts of A. muscaria is ingested, it often results in severe illness but even then the victim usually recover.

The most well known species of mushroom, having toxins in this group is Amanita muscaria (Fly Agaric). Although neither the scientific nor common name is familiar to the layperson, this species, with its scarlet pileus that is covered with yellowish-white spots, is the model for mushrooms used in many children's books and greeting cards. This species forms mycorrhizae with pine trees and is common in temperate areas of the world. However, it is recorded from Hawai‘i, only on the island of Kaua‘i. This mushroom was thought by Wasson (1968) to be the Soma that had been used in religious ceremonies over 4,000 years ago and is known to have been used by local tribes of Siberia for their religious ceremonies, as well. More information concerning the above connections to A. muscaria can be seen here.

Group VII. Psilocybin and psilocin: This group of toxins is perhaps the most well known. They are in the LSD family of hallucinogenic compounds. The toxins in this group have a strong effect on the central nervous system. Some of the common symptoms include uncontrollable laughter, hallucinations, optical distortions, euphoria and disembodied experience; and some victims have reported experiencing religious or mystical experiences. However, “bad trips” may also occur causing the victim to become anxious to paranoid, and may require considerable reassurance or, more rarely, even tranquilizers. The effects are normally about 4-5 hours, followed by sleep. The quantity ingested, physiological condition, personality and mood of the subject are all apparently involved in how ingestion will affect the user. Since as little as 5 mg. of Psilocybe cubensis can cause visual hallucinations in 15 minutes, it is obvious that the ingestion of large quantities of some mushrooms in this group can be fatal or cause severe toxic effects. Perhaps the most important factor is the presence of other toxic compounds in addition to the hallucinogenic agent in a given species. Hallucinations may be suppressed by chlorpromazine, and convulsions by diazepam.

Toxins are found in several common genera of mushrooms: Psilocybe, Panaeolus, Conocybe and Gymnopilus, to name a few. Species of these mushrooms as used by Native Americans, in Mexico, for religious ceremonies have been well studied.

Group VIII. Gastrointestinal Irritants: This is a group of unrelated toxins. However, they all cause similar symptoms when consumed. Symptoms from the mushroom begin 30-90 minutes following consumption. All cause varying degrees of digestive upset. Commonest symptoms are diarrhea, vomiting and abdominal cramps. Normally, symptoms clear up in 3-4 hours and complete recovery several days later. Some cases of fatality have been recorded, but these are usually cases in which large quantities of mushrooms have been consumed or if the victims were young children. There are a number of fungi in Hawai‘i that have these toxins. They include Agaricus, Chlorophyllum, Marasmius, Naematoloma, Pholiota, Scleroderma and probably many others. Because the toxins that cause these symptoms have not been identified, treatment has been restricted to emptying the stomach.

Summary of Toxins

The seven group of toxins can be divided into four categories according to the matter in which they affect the consumer:

• Toxins belong to Groups I, II, and III. Toxins that cause extensive cellular damage, followed by physical symptoms, which appear only after cellular damage has occurred and is often no longer treatable.

• Toxins belong to Groups IV and V. Toxins affect the autonomic system, with symptoms appearing shortly after consumption or when the appropriate substrate enters the system.

• Toxins belonging to Groups VI and VII. Toxins affecting the central nervous system and causing hallucination. Symptoms appear shortly after consumption.

• Toxins belonging to Group VIII. The unidentified toxins, which cause gastrointestinal discomfort as soon as they are consumed.

There is a lot of information in this lecture, especially with respect to details of symptoms. What you should emphasize are the specific terms and questions below. Note that you have had several of the terms in previous lectures:

Some Poisonous Mushroom Terms

Amatoxins: One of two categories of Class I toxin that may be lethal when consumed.

Coprine: Toxin that affects the consumer with symptoms only if alcoholic beverages are consumed with the toxin. Symptoms include hot flushes of the face and neck, a metallic taste in the mouth, tingling sensations in the limbs, numbness in the hands, palpitations, a throbbing headache, nausea and vomiting. The symptoms will continue as long as there is any alcohol in the victim's stomach.

Ibotenic acid: One of the two main toxins in Class VI toxins. The other being Muscimol. This toxin is the weaker of the two. Toxin affects the central nervous system are comparable to alcohol intoxication. Onset of symptoms usually occurs between 30-120 minutes after ingestion of mushrooms containing this toxin. These symptoms include nausea and vomiting, inability to walk or walking only with a drunken gait, alternation between being uncontrollably active and difficult to rouse, followed by a deep sleep with dreams, lasting about two hours. Not all of these symptoms can be attributed to ibotenic acid. Other toxins are present that probably cause nausea and vomiting.

Muscimol: One of the two main toxins in Class VI toxins. The other being Ibotenic acid. This toxin is much more potent than the latter. Toxin affects the central nervous system are compared to alcohol intoxication. Onset of symptoms usually occurs between 30-120 minutes. These symptoms include nausea and vomiting, inability to walk or walking only with a drunken gait, alternation between being uncontrollably active and difficult to rouse, followed by a deep sleep with dreams, lasting about two hours.

Phallotoxins: One of two categories of Class I toxin. It was once believed that the phallotoxins contributed in poisoning the consumer, but apparently only the amatoxins are responsible. When a phallotoxins are directly injected into mice, they are up to ten times more lethal than cyanide, but when taken orally, phallotoxins have no effect.

Psilocin: The toxin has a strong effect on the central nervous system. Some of the common symptoms include uncontrollable laughter, hallucinations, optical distortions, euphoria and disembodied experience; and some victims have reported experiencing religious or mystical experiences. Symptoms begin approximately 10-30 minutes after consumption. The effects are normally about 4-5 hours, followed by sleep.

Psilocybin: The toxin has a strong effect on the central nervous system. Some of the common symptoms include uncontrollable laughter, hallucinations, optical distortions, euphoria and disembodied experience; and some victims have reported experiencing religious or mystical experiences. Symptoms begin approximately 10-30 minutes after consumption. The effects are normally about 4-5 hours, followed by sleep.

Questions to Think About

1. How do “mushrooms” and “toadstools” differ?

2. What are some myths concerning poisonous and edible mushrooms?

3. What genus has the world’s most deadliest species of mushrooms?

4. What are the characteristics that will tell you when you have a species of Amanita?

5. How safe is it to collect mushrooms for the purpose of eating?

6. What are the symptoms of ingestion of mushrooms that have toxins in Classes I, V, VI and VII?

7. How does it become known as to whether a species of mushroom is poisonous or not?

8. Are “edible mushrooms” always safe to eat?