Some Zoanthid coral species popular with marine aquarium enthusiasts can contain Palytoxin. This toxin is dangerous to your health and being exposed to it can have potentially life-threatening consequences.
Palytoxin poisoning emergency
Anyone who becomes ill after handling marine coral should seek urgent medical attention by going to the nearest emergency department or medical clinic.
If you suspect a person has been exposed to Palytoxin, contact the Poisons Information Centre on 13 11 26 for first aid advice and explain if it is necessary to seek immediate medical attention.
Zoanthid corals are soft corals known as colony-forming anemones. These decorative ornamental corals are commonly called ‘button polyps’, ‘sun polyps’ or ‘zoas’.
Species of Zoanthid coral (for example Palythoa species and Zoanthus species) can contain a highly toxic, naturally-occurring and potentially lethal substance known as Palytoxin.
Zoanthid corals are often recommended to new marine aquarium owners because they are considered to be relatively easy to keep. Health risks associated with keeping soft corals in home aquariums are often unrecognised or underestimated by aquarium enthusiasts and suppliers because there are limited cases documented to raise awareness.
How do you know if a coral is poisonous?
It is not possible to tell which Zoanthid corals contain Palytoxin when deciding whether to keep them in aquariums. While it is possible that people may not intend to buy Zoanthids – it is important to remember that other types of coral or any ‘live rock’ bought from aquarium suppliers may unintentionally contain Zoanthids.
Marine aquarium owners should always presume Palytoxin is present and take appropriate precautions when handling corals to avoid being exposed to this toxin.
Protect yourself and your family
Keep general handling of corals to a minimum.
Do not handle coral with your bare hands. Barrier protection for example protective eyewear and gloves should always be worn when coral is handled. Latex gloves break easily when handling sharp rocks so long thick rubber industrial gloves that protect your hands and forearms are recommended.
Always handle coral under water. Bag the live rock plus water at a distance from aquarium lighting (the warming effect in shallow water can trigger Palytoxin release) while wearing protective equipment and seal the bag before removing from the aquarium,
Monitor aquarium water levels closely to make sure coral surface is completely submerged at all times (particularly with evaporation under aquarium lights)
Avoid any coral maintenance activity that can potentially produce aerosols for example breaking, cutting, scrubbing (even with cold water), scraping, brushing and using boiling water or chemicals.
Avoid placing coral under powerful halide lights when out of the water. Halide lights used to sustain and raise new coral colonies can cause heat stress in corals that are out of the water causing rapid release of Palytoxin.
Avoid splashing and contaminating nearby surfaces when changing tank water, and dispose of aquarium water carefully as it can contain Palytoxin.
Remember that Palytoxin can travel some distance in water aerosols.
Be aware that Palytoxin is heat stable – heating does not remove the toxin but it can be deactivated using bleach.
Palytoxin poisoning is relatively rare, with most cases occurring after eating contaminated seafood. Fatalities in these circumstances have been reported.
Exposure to Palytoxin can also occur by direct contact with intact or damaged skin, by direct contact with eyes or by inhaling aerosols or steam vapours associated with aquariums or the natural marine environment.
Zoanthid corals readily proliferate, become overgrown and colonise other corals; forming large, tightly attached colonies that are difficult to thin out. This increases the potential for aquarium enthusiasts to be exposed to Palytoxin.
Most aquarium-related cases occur as a result of skin exposure after prolonged handling through cuts on hands or inhalation of coral dust, steam vapours or water droplets and aerosols while cleaning, separating, growing/propagating, collecting, transporting mechanically removing or eradicating over-growing corals by pouring boiling water on live rock as well as cleaning home marine aquariums.
Although poisonings are relatively rare it is important to be aware that Palytoxin poses a significant risk to human safety due to its extreme toxicity.
Symptoms can occur and progress rapidly within minutes to hours after handling coral.
Severity depends on how long people have been exposed, the distance they were from the location where coral was being handled, the route of exposure and the presence of cuts or abrasions on hands (Palytoxin can easily pass through a skin wound and reach the bloodstream).
Flu-like symptoms: such as coughing, fever, chills, sore throat, headache, muscle aches, chest pain, respiratory distress.
Neurological symptoms: fatigue, dizziness, speech disturbance, bitter metallic taste, tremors, tingling or numbness of extremities.
Muscle symptoms: pain, weakness, cramps, spasms.
Cardiac effects: irregular, slow, fast hear rate, cardiac muscle damage, low or high blood pressure
Severe cases report muscle breakdown, kidney failure, coma and death from cardiac or respiratory failure. There is no specific treatment of antidote for Palytoxin poisoning with medical treatment limited generally to supportive care.
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