Human risk associated with palytoxin exposure.

Palytoxin (PTX) was first isolated from the zoanthid Palythoa toxica. Evaluation of PTX toxicity using various animal models determined that PTX was extremely potent through intravenous, intraperitoneal, and intratracheal exposure. PTX was less potent by direct intragastric exposure. PTX also caused significant, non-lethal effects through dermal and ocular exposure. PTX and PTX-like compounds have now been found in additional zoanthid species, red alga, a sea anemone, and several dinoflagellates. PTXs are found throughout certain reef associated food webs, including in fish and crabs responsible for human illness and death. Many of the organisms found to contain PTXs in the environment are also sold in the home aquarium trade, and recent evidence suggests poisonings have occurred through exposure to these organisms. Due to co-occurrence with other seafood toxins, such as ciguatoxins, saxitoxins, and tetrodotoxin, it has been difficult to assess the true risk of PTX poisoning through seafood consumption in humans, but limited cases have been well documented, some involving human fatalities. Recent evidence also suggests that humans are negatively impacted through PTX exposure by inhalation and dermal routes. Continued research into the distribution and occurrence of PTX and PTX-like compounds both in seafood and marine organisms sold in the aquarium trade appears warranted.