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Deep Learning Technology: Sebastian Arnold, Betty van Aken, Paul Grundmann, Felix A. Gers and Alexander Löser. Learning Contextualized Document Representations for Healthcare Answer Retrieval. The Web Conference 2020 (WWW'20)
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Since lead has been used widely for centuries, the effects of exposure are worldwide. Environmental lead is ubiquitous, and everyone has some measurable blood lead level. Atmospheric lead pollution increased dramatically beginning in the 1950s as a result of the widespread use of leaded gasoline. Lead is one of the largest environmental medicine problems in terms of numbers of people exposed and the public health toll it takes. Lead exposure accounts for about 0.2% of all deaths and 0.6% of disability adjusted life years globally.
Although regulation reducing lead in products has greatly reduced exposure in the developed world since the 1970s, lead is still allowed in products in many developing countries. In all countries that have banned leaded gasoline, average blood lead levels have fallen sharply. However, some developing countries still allow leaded gasoline, which is the primary source of lead exposure in most developing countries. Beyond exposure from gasoline, the frequent use of pesticides in developing countries adds a risk of lead exposure and subsequent poisoning. Poor children in developing countries are at especially high risk for lead poisoning. Of North American children, 7% have blood lead levels above 10 μg/dL, whereas among Central and South American children, the percentage is 33 to 34%. About one fifth of the world's disease burden from lead poisoning occurs in the Western Pacific, and another fifth is in Southeast Asia.
In developed countries, people with low levels of education living in poorer areas are most at risk for elevated lead. In the US, the groups most at risk for lead exposure are the impoverished, city-dwellers, and immigrants. African-American children and those living in old housing have also been found to be at elevated risk for high blood lead levels in the US. Low-income people often live in old housing with lead paint, which may begin to peel, exposing residents to high levels of lead-containing dust.
Risk factors for elevated lead exposure include alcohol consumption and smoking (possibly because of contamination of tobacco leaves with lead-containing pesticides). Adults with certain risk factors might be more susceptible to toxicity; these include calcium and iron deficiencies, old age, disease of organs targeted by lead (e.g. the brain, the kidneys), and possibly genetic susceptibility.
Differences in vulnerability to lead-induced neurological damage between males and females have also been found, but some studies have found males to be at greater risk, while others have found females to be.
In adults, blood lead levels steadily increase with increasing age. In adults of all ages, men have higher blood lead levels than women do. Children are more sensitive to elevated blood lead levels than adults are. Children may also have a higher intake of lead than adults; they breathe faster and may be more likely to have contact with and ingest soil. Children of ages one to three tend to have the highest blood lead levels, possibly because at that age they begin to walk and explore their environment, and they use their mouths in their exploration. Blood levels usually peak at about 18–24 months old. In many countries including the US, household paint and dust are the major route of exposure in children.
Outcome is related to the extent and duration of lead exposure. Effects of lead on the physiology of the kidneys and blood are generally reversible; its effects on the central nervous system are not. While peripheral effects in adults often go away when lead exposure ceases, evidence suggests that most of lead's effects on a child's central nervous system are irreversible. Children with lead poisoning may thus have adverse health, cognitive, and behavioral effects that follow them into adulthood.
Chronic arsenic poisoning results from drinking contaminated well water over a long period of time. Many aquifers contain high concentration of arsenic salts. The World Health Organization (WHO) recommends a limit of 0.01 mg/L (10 parts per billion) of arsenic in drinking water. This recommendation was established based on the limit of detection for most laboratories' testing equipment at the time of publication of the WHO water quality guidelines. More recent findings show that consumption of water with levels as low as 0.00017 mg/L (0.17 parts per billion) over long periods of time can lead to arsenicosis.
From a 1988 study in China, the US protection agency quantified the lifetime exposure of arsenic in drinking water at concentrations of 0.0017 mg/L, 0.00017 mg/L, and 0.000017 mg/L are associated with a lifetime skin cancer risk of 1 in 10,000, 1 in 100,000, and 1 in 1,000,000 respectively. WHO asserts that a level of 0.01 mg/L poses a risk of 6 in 10000 chance of lifetime skin cancer risk and contends that this level of risk is acceptable.
One of the worst incidents of arsenic poisoning via well water occurred in Bangladesh, which the World Health Organization called the "largest mass poisoning of a population in history."
Mining techniques such as hydraulic fracturing may mobilize arsenic in groundwater and aquifers due to enhanced methane transport and resulting changes in redox conditions, and inject fluid containing additional arsenic.
Some of the toxic effects of mercury are partially or wholly reversible, either through specific therapy or through natural elimination of the metal after exposure has been discontinued. Autopsy findings point to a half-life of inorganic mercury in human brains of 27.4 years. Heavy or prolonged exposure can do irreversible damage, in particular in fetuses, infants, and young children. Young's syndrome is believed to be a long-term consequence of early childhood mercury poisoning.
Mercuric chloride may cause cancer as it has caused increases in several types of tumors in rats and mice, while methyl mercury has caused kidney tumors in male rats. The EPA has classified mercuric chloride and methyl mercury as possible human carcinogens (ATSDR, EPA)
Organic arsenic is less harmful than inorganic arsenic. Seafood is a common source of the less toxic organic arsenic in the form of arsenobetaine. The arsenic reported in 2012 in fruit juice and rice by "Consumer Reports" was primarily inorganic arsenic.
Methylmercury is the major source of organic mercury for all individuals. Due to bioaccumulation it works its way up through the food web and thus biomagnifies, resulting in high concentrations among populations of some species. Top predatory fish, such as tuna or swordfish, are usually of greater concern than smaller species. The US FDA and the EPA advise women of child-bearing age, nursing mothers, and young children to completely avoid swordfish, shark, king mackerel and tilefish from the Gulf of Mexico, and to limit consumption of albacore ("white") tuna to no more than per week, and of all other fish and shellfish to no more than per week. A 2006 review of the risks and benefits of fish consumption found, for adults, the benefits of one to two servings of fish per week outweigh the risks, even (except for a few fish species) for women of childbearing age, and that avoidance of fish consumption could result in significant excess coronary heart disease deaths and suboptimal neural development in children.
The period between exposure to methylmercury and the appearance of symptoms in adult poisoning cases is long. The longest recorded latent period is five months after a single exposure, in the Dartmouth case (see History); other latent periods in the range of weeks to months have also been reported. No explanation for this long latent period is known. When the first symptom appears, typically paresthesia (a tingling or numbness in the skin), it is followed rapidly by more severe effects, sometimes ending in coma and death. The toxic damage appears to be determined by the peak value of mercury, not the length of the exposure.
Methylmercury exposure during rodent gestation, a developmental period that approximately models human neural development during the first two trimesters of gestation, has long-lasting behavioral consequences that appear in adulthood and, in some cases, may not appear until aging. Prefrontal cortex or dopamine neurotransmission could be especially sensitive to even subtle gestational methylmercury exposure and suggests that public health assessments of methylmercury based on intellectual performance may underestimate the impact of methylmercury in public health.
Ethylmercury is a breakdown product of the antibacteriological agent ethylmercurithiosalicylate, which has been used as a topical antiseptic and a vaccine preservative (further discussed under Thiomersal below). Its characteristics have not been studied as extensively as those of methylmercury. It is cleared from the blood much more rapidly, with a half-life of seven to 10 days, and it is metabolized much more quickly than methylmercury. It is presumed not to have methylmercury's ability to cross the blood–brain barrier via a transporter, but instead relies on simple diffusion to enter the brain. Other exposure sources of organic mercury include phenylmercuric acetate and phenylmercuric nitrate. These compounds were used in indoor latex paints for their antimildew properties, but were removed in 1990 because of cases of toxicity.
Acute hydrogen cyanide poisoning can result from inhalation of fumes from burning polymer products that use nitrile in their production, such as polyurethane, or vinyl. It can also be caused by breakdown of nitroprusside into nitric oxide and cyanide. Nitroprusside may be used during treatment of hypertensive crisis.
In addition to its uses as a pesticide and insecticide, cyanide is contained in tobacco smoke and smoke from building fires, and is present in many seeds or kernels such as those of almonds, apricots, apples, oranges, and in foods including cassava (also known as yuca or manioc), and bamboo shoots. Vitamin B12, in the form of hydroxocobalamin (also spelled hydroxycobalamin), may reduce the negative effects of chronic exposure, and a deficiency can lead to negative health effects following exposure.
The most common source of ethylene glycol is automotive antifreeze or radiator coolant, where concentrations are high. Other sources of ethylene glycol include windshield deicing agents, brake fluid, motor oil, developing solutions for hobby photographers, wood stains, solvents, and paints. Some people put antifreeze into their cabin’s toilet to prevent it from freezing during the winter, resulting in toxicities when animals drink from the toilet. Small amounts of ethylene glycol may be contained in holiday ornaments such as snow globes.
The most significant source of ethylene glycol is from aircraft de-icing and anti-icing operations, where it is released onto land and eventually to waterways near airports experiencing cold winter climates. It is also used in manufacturing polyester products. In 2006, approximately 1540 kilotonnes of ethylene glycol were manufactured in Canada by three companies in Alberta, with most of the production destined for export.
Decontamination of people exposed to hydrogen cyanide gas only requires removal of the outer clothing and the washing of their hair. Those exposed to liquids or powders generally require full decontamination.
The mortality rates from AAlPP vary from 40 to 80 percent. The actual numbers of cases may be much larger, as less than five percent of those with AAlPP eventually reach a tertiary care center. Since 1992, when aluminium phosphide became freely available in the market, it had, reportedly, overtaken all other forms of deliberate poisoning, such as organophosphorus and barbiturate poisoning, in North India. In a 25-year-long study on 5,933 unnatural deaths in northwest India, aluminium phosphide poisoning was found to be the major cause of death among all cases of poisonings.
It is difficult to differentiate the effects of low level metal poisoning from the environment with other kinds of environmental harms, including nonmetal pollution. Generally, increased exposure to heavy metals in the environment increases risk of developing cancer.
Without a diagnosis of metal toxicity and outside of evidence-based medicine, but perhaps because of worry about metal toxicity, some people seek chelation therapy to treat autism, cardiovascular disease, Alzheimer's disease, or any sort of neurodegeneration. Chelation therapy does not improve outcomes for those diseases.
Ethylene glycol has been shown to be toxic to humans and is also toxic to domestic pets such as cats and dogs. A toxic dose requiring medical treatment varies but is considered more than 0.1 mL per kg body weight (mL/kg) of pure substance. That is roughly 16 mL of 50% ethylene glycol for an 80 kg adult and 4 mL for a 20 kg child. Poison control centers often use more than a lick or taste in a child or more than a mouthful in an adult as a dose requiring hospital assessment.
The orally lethal dose in humans has been reported as approximately 1.4 mL/kg of pure ethylene glycol. That is approximately 224 mL (7.6 oz.) of 50% ethylene glycol for an 80 kg adult and 56 mL (2 oz.) for a 20 kg child. Although survival with medical treatment has occurred with doses much higher than this, death has occurred with 30 mL of the concentrate in an adult. In the EU classification of dangerous substances it is 'harmful' (Xn) while more toxic substances are classified as 'toxic' (T) or 'very toxic' (T+). The U.S. Environmental Protection Agency generally puts substances which are lethal at more than 30 g to adults in Toxicity Class III.
Ethylene glycol has a low vapor pressure; it does not evaporate readily at normal temperatures and therefore high concentrations in air or intoxication are unlikely to occur following inhalational exposures. There may be a slight risk of poisoning where mists or fogs are generated, although this rarely leads to poisoning as ethylene glycol causes irritation and coughing when breathed in, alerting victims to its presence. Ethylene glycol is not well absorbed through skin meaning poisoning following dermal exposure is also uncommon.
Several foods can naturally contain toxins, many of which are not produced by bacteria. Plants in particular may be toxic; animals which are naturally poisonous to eat are rare. In evolutionary terms, animals can escape being eaten by fleeing; plants can use only passive defenses such as poisons and distasteful substances, for example capsaicin in chili peppers and pungent sulfur compounds in garlic and onions. Most animal poisons are not synthesised by the animal, but acquired by eating poisonous plants to which the animal is immune, or by bacterial action.
- Alkaloids
- Ciguatera poisoning
- Grayanotoxin (honey intoxication)
- Mushroom toxins
- Phytohaemagglutinin (red kidney bean poisoning; destroyed by boiling)
- Pyrrolizidine alkaloids
- Shellfish toxin, including paralytic shellfish poisoning, diarrhetic shellfish poisoning, neurotoxic shellfish poisoning, amnesic shellfish poisoning and ciguatera fish poisoning
- Scombrotoxin
- Tetrodotoxin (fugu fish poisoning)
Some plants contain substances which are toxic in large doses, but have therapeutic properties in appropriate dosages.
- Foxglove contains cardiac glycosides.
- Poisonous hemlock (conium) has medicinal uses.
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).
Rotten mushrooms may cause food poisoning. Mushrooms that are mushy, bad-smelling, or moldy (even of a choice edible species) may be toxic due to bacterial decay or mold.
Many mushrooms are high in fiber. Excessive consumption of mushrooms may lead to indigestion, which may be diagnosed as mushroom "poisoning".
Even though zinc is an essential requirement for a healthy body, excess zinc can be harmful, and cause zinc toxicity. Such toxicity levels have been seen to occur at ingestion of greater than 225 mg of Zinc. Excessive absorption of zinc can suppress copper and iron absorption. The free zinc ion in solution is highly toxic to bacteria, plants, invertebrates, and even vertebrate fish.
There are two main methods of removing both radioactive and stable isotopes of thallium from humans. First known was to use Prussian blue, which is a solid ion exchange material, which absorbs thallium. Up to 20 g per day of Prussian blue is fed by mouth to the person, and it passes through their digestive system and comes out in the stool. Hemodialysis and hemoperfusion are also used to remove thallium from the blood serum. At later stage of the treatment additional potassium is used to mobilize thallium from the tissue.
New species of fungi are continuing to be discovered, with an estimated number of 800 new species registered annually. This, added to the fact that many investigations have recently reclassified some species of mushrooms from edible to poisonous has made older classifications insufficient at describing what now is known about the different species of fungi that are harmful to humans. Thus, contrary to what older registers state, it is now thought that of the approximately 100,000 known fungi species found worldwide, about 100 of them are poisonous to humans. However, by far the majority of mushroom poisonings are not fatal, and the majority of fatal poisonings are attributable to the "Amanita phalloides" mushroom.
A majority of these cases are due to mistaken identity. This is a common occurrence with "A. phalloides" in particular, due to its resemblance to the Asian paddy-straw mushroom, "Volvariella volvacea". Both are light-colored and covered with a universal veil when young.
"Amanita"s can be mistaken for other species, as well, in particular when immature. On at least one occasion they have been mistaken for "Coprinus comatus". In this case, the victim had some limited experience in identifying mushrooms, but did not take the time to correctly identify these particular mushrooms until after he began to experience symptoms of mushroom poisoning.
The author of "Mushrooms Demystified", David Arora cautions puffball-hunters to beware of "Amanita" "eggs", which are "Amanita"s still entirely encased in their universal veil. "Amanita"s at this stage are difficult to distinguish from puffballs. Foragers are encouraged to always cut the fruiting bodies of suspected puffballs in half, as this will reveal the outline of a developing "Amanita" should it be present within the structure.
A majority of mushroom poisonings in general are the result of small children, especially toddlers in the "grazing" stage, ingesting mushrooms found in the lawn. While this can happen with any mushroom, "Chlorophyllum molybdites" is often implicated due to its preference for growing in lawns. "C. molybdites" causes severe gastrointestinal upset but is not considered deadly poisonous.
A few poisonings are the result of misidentification while attempting to collect hallucinogenic mushrooms for recreational use. In 1981, one fatality and two hospitalizations occurred following consumption of "Galerina autumnalis", mistaken for a "Psilocybe" species. "Galerina" and "Psilocybe" species are both small, brown, and sticky, and can be found growing together. However, "Galerina" contains amatoxins, the same poison found in the deadly "Amanita" species. Another case reports kidney failure following ingestion of "Cortinarius orellanus", a mushroom containing orellanine.
It is natural that accidental ingestion of hallucinogenic species also occurs, but is rarely harmful when ingested in small quantities. Cases of serious toxicity have been reported in small children. "Amanita pantherina", while containing the same hallucinogens as "Amanita muscaria" (e.g., ibotenic acid and muscimol), has been more commonly associated with severe gastrointestinal upset than its better-known counterpart.
Although usually not fatal, "Omphalotus" spp., "Jack-o-lantern mushrooms," are another cause of sometimes significant toxicity. They are sometimes mistaken for chanterelles. Both are bright-orange and fruit at the same time of year, although "Omphalotus" grows on wood and has true gills rather than the veins of a "Cantharellus". They contain toxins known as illudins, which causes gastrointestinal symptoms.
Bioluminescent species are generally inedible and often mildly toxic.
"Clitocybe dealbata", which is occasionally mistaken for an oyster mushroom or other edible species contains muscarine.
Toxicities can also occur with collection of morels. Even true morels, if eaten raw, will cause gastrointestinal upset. Typically, morels are thoroughly cooked before eating. "Verpa bohemica", although referred to as "thimble morels" or "early morels" by some, have caused toxic effects in some individuals. "Gyromitra" spp., "false morels", are deadly poisonous if eaten raw. They contain a toxin called gyromitrin, which can cause neurotoxicity, gastrointestinal toxicity, and destruction of the blood cells. The Finns consume "Gyromitra esculenta" after parboiling, but this may not render the mushroom entirely safe, resulting in its being called the "fugu of the Finnish cuisine".
A more unusual toxin is coprine, a disulfiram-like compound that is harmless unless ingested within a few days of ingesting alcohol. It inhibits aldehyde dehydrogenase, an enzyme required for breaking down alcohol. Thus, the symptoms of toxicity are similar to being hung over—flushing, headache, nausea, palpitations, and, in severe cases, trouble breathing. "Coprinus" species, including "Coprinopsis atramentaria", contain coprine. "Coprinus comatus" does not, but it is best to avoid mixing alcohol with other members of this genus.
Recently, poisonings have also been associated with "Amanita smithiana". These poisonings may be due to orellanine, but the onset of symptoms occurs in 4 to 11 hours, which is much quicker than the 3 to 20 days normally associated with orellanine.
"Paxillus involutus" is also inedible when raw, but is eaten in Europe after pickling or parboiling. However, after the death of the German mycologist Dr Julius Schäffer, it was discovered that the mushroom contains a toxin that can stimulate the immune system to attack its own red blood cells. This reaction is rare, but can occur even after safely eating the mushroom for many years. Similarly, "Tricholoma equestre" was widely considered edible and good, until it was connected with rare cases of rhabdomyolysis.
In the fall of 2004, thirteen deaths were associated with consumption of "Pleurocybella porrigens" or "angel's wings". In general, these mushrooms are considered edible. All the victims died of an acute brain disorder, and all had pre-existing kidney disease. The exact cause of the toxicity was not known at this time and the deaths cannot be definitively attributed to mushroom consumption.
However, mushroom poisoning is not always due to mistaken identity. For example, the highly toxic ergot "Claviceps purpurea", which grows on rye, is sometimes ground up with rye, unnoticed, and later consumed. This can cause devastating, even fatal effects, which is called ergotism.
Cases of idiosyncratic or unusual reactions to fungi can also occur. Some are probably due to allergy, others to some other kind of sensitivity. It is not uncommon for an individual person to experience gastrointestinal upset associated with one particular mushroom species or genus.
The true number of cases of carbon monoxide poisoning is unknown, since many non-lethal exposures go undetected. From the available data, carbon monoxide poisoning is the most common cause of injury and death due to poisoning worldwide. Poisoning is typically more common during the winter months. This is due to increased domestic use of gas furnaces, gas or kerosene space heaters, and kitchen stoves during the winter months, which if faulty and/or used without adequate ventilation, may produce excessive carbon monoxide. Carbon monoxide detection and poisoning also increases during power outages, when electric heating and cooking appliances become inoperative and residents may temporarily resort to fuel-burning space heaters, stoves, and grills (some of which are safe only for outdoor use but nonetheless are errantly burned indoors).
It has been estimated that more than 40,000 people per year seek medical attention for carbon monoxide poisoning in the United States. 95% of carbon monoxide poisoning deaths in the United States are due to gas space heaters. In many industrialized countries carbon monoxide is the cause of more than 50% of fatal poisonings. In the United States, approximately 200 people die each year from carbon monoxide poisoning associated with home fuel-burning heating equipment. Carbon monoxide poisoning contributes to the approximately 5613 smoke inhalation deaths each year in the United States. The CDC reports, "Each year, more than 500 Americans die from unintentional carbon monoxide poisoning, and more than 2,000 commit suicide by intentionally poisoning themselves." For the 10-year period from 1979 to 1988, 56,133 deaths from carbon monoxide poisoning occurred in the United States, with 25,889 of those being suicides, leaving 30,244 unintentional deaths. A report from New Zealand showed that 206 people died from carbon monoxide poisoning in the years of 2001 and 2002. In total carbon monoxide poisoning was responsible for 43.9% of deaths by poisoning in that country. In South Korea, 1,950 people had been poisoned by carbon monoxide with 254 deaths from 2001 through 2003. A report from Jerusalem showed 3.53 per 100,000 people were poisoned annually from 2001 through 2006. In Hubei, China, 218 deaths from poisoning were reported over a 10-year period with 16.5% being from carbon monoxide exposure.
When thinking of pesticide poisoning, one does not take into consideration the contribution that is made of their own household. The majority of households in Canada use pesticides while taking part in activities such as gardening. In Canada 96 percent of households report having a lawn or a garden. 56 percent of the households who have a lawn or a garden utilize fertilizer or pesticide. This form of pesticide use may contribute to the third type of poisoning, which is caused by long-term low-level exposure. As mentioned before, long-term low-level exposure affects individuals from sources such as pesticide residues in food as well as contact with pesticide residues in the air, water, soil, sediment, food materials, plants and animals.
The following guideline values (ppm values rounded) and periods of time-weighted average exposures have been determined in such a way that the carboxyhaemoglobin (COHb) level of 2.5% is not exceeded, even when a normal subject engages in light or moderate exercise:
- 100 mg/m3 (87 ppm) for 15 min
- 60 mg/m3 (52 ppm) for 30 min
- 30 mg/m3 (26 ppm) for 1 h
- 10 mg/m3 (9 ppm) for 8 h
For indoor air quality 7 mg/m3 (6 ppm) for 24 h (so as not to exceed 2% COHb for chronic exposure)
Cows and horses as well as pet animals are also susceptible to the effects of lead toxicity. Sources of lead exposure in pets can be the same as those that present health threats to humans sharing the environment, such as paint and blinds, and there is sometimes lead in toys made for pets. Lead poisoning in a pet dog may indicate that children in the same household are at increased risk for elevated lead levels.
OP pesticide exposure occurs through inhalation, ingestion and dermal contact. Because OP pesticides disintegrate quickly in air and light, they have been considered relatively safe to consumers. However, OP residues linger on fruits and vegetables. Certain OP pesticides have been banned for use on some crops, for example methyl parathion is banned from use on some crops while permitted on others.
The Environmental Working Group has developed lists for concerned consumers, identifying crops with the highest pesticide residue quantities and the lowest. The "Dirty Dozen" crops are updated yearly and in 2012 included apples, celery, sweet bell peppers, peaches, strawberries, imported nectarines, grapes, spinach, lettuce, cucumbers, domestic blueberries and potatoes. Forty-five fruits and vegetables are listed by the Environmental Working Group as being regularly found with pesticide residue associated with OPs.
Heavy metals "can bind to vital cellular components, such as structural proteins, enzymes, and nucleic acids, and interfere with their functioning". Symptoms and effects can vary according to the metal or metal compound, and the dose involved. Broadly, long-term exposure to toxic heavy metals can have carcinogenic, central and peripheral nervous system and circulatory effects. For humans, typical presentations associated with exposure to any of the "classical" toxic heavy metals, or chromium (another toxic heavy metal) or arsenic (a metalloid), are shown in the table.
The International Agency for Research on Cancer (IARC), found that organophosphates may possibly increased cancer risk. Tetrachlorvinphos and parathion were classified as "possibly carcinogenic", malathion, and diazinon.
Ciguatera is a foodborne illness caused by eating certain reef fish whose flesh is contaminated with a toxin made by dinoflagellates such as "Gambierdiscus toxicus" which live in tropical and subtropical waters. These dinoflagellates adhere to coral, algae and seaweed, where they are eaten by herbivorous fish which in turn are eaten by larger carnivorous fish like barracudas, shark, and even omnivorous fish like basses and other fish like mullet. This is called biomagnification. Affected fish may show no sign of infection or, in more advanced cases, will be weakened and visibly thin, with yellowish eyes. As well, fish may be pale or a different color than usual.
"Gambierdiscus toxicus" is the primary dinoflagellate responsible for the production of a number of similar polyether toxins, including ciguatoxin, maitotoxin, gambieric acid and scaritoxin, as well as the long-chain alcohol palytoxin. Other dinoflagellates that may cause ciguatera include "Prorocentrum" spp., "Ostreopsis" spp., "Coolia monotis", "Thecadinium" spp. and "Amphidinium carterae". Predator species near the top of the food chain in tropical and subtropical waters are most likely to cause ciguatera poisoning, although many other species cause occasional outbreaks of toxicity.
Ciguatoxin is odourless, tasteless and cannot be removed by conventional cooking.
Researchers such as Ross M. Brown with his "New Religion" theory suggest that ciguatera outbreaks caused by warm climatic conditions in part propelled the migratory voyages of Polynesians between 1000 and 1400AD.
In 2017 an updated review of "Clinical, Epidemiological, Environmental, and Public Health Management" was published and is available at the National Institute of Health website.