Paralytic Shellfish Poisoning
Paralytic shellfish poisoning (PSP) is a serious illness caused by eating shellfish contaminated with algae that contains Paralytic Shellfish Toxin (PST), a toxin harmful to humans. This toxin is extremely poisonous; as little as one milligram (0.000035 ounce) is enough to kill an adult.
Shellfish feed by filtering food particles, including algae, from ingested water. When they filter and eat biotoxin-producing algae, the PST accumulates in their tissue.
All molluscan shellfish (those having a hinged shell), including clams, mussels, geoducks, oysters, snails and scallops may be contaminated. Crab meat is not known to contain the toxin, but they feed on shellfish, so it’s possible the guts may contain unsafe levels of PST. To be safe, clean crab thoroughly, removing all butter (the white-yellow fat inside the back of the shell), and discard the gut. Shrimp and finfish are not known to contain the toxin.
Restaurants and stores must purchase shellfish from certified growers. Certified growers are required to have their products regularly tested for PST.
The toxin is not destroyed by cooking or freezing.
No. Shellfish containing PST may not look, smell or taste any different than uncontaminated shellfish.
Early symptoms include tingling of the lips and tongue, which may begin within minutes of eating poisonous shellfish or may take an hour or two to develop. Depending upon the amount of toxin a person has ingested, symptoms may progress to tingling of fingers and toes and then loss of control of arms and legs, followed by difficulty in breathing. Some people have experienced a sense of floating or nausea. If a person consumes enough poison, muscles of the chest and abdomen become paralyzed. Death can result in as little as two hours, as muscles used for breathing become paralyzed.
The only treatment for severe cases is the use of a mechanical respirator and oxygen. If symptoms are exhibited, call 911, or get to a medical facility immediately.
PSP in Alaska – How to avoid Paralytic Shellfish Poisoning
- Don’t eat shellfish harvested from untested Alaska beaches.
- Don’t eat the viscera (guts) of crab. Because PSP has been found in crab viscera, it is recommended that crab be cleaned and eviscerated before being cooked.
- Cooking will not destroy the toxin. Freezing will not destroy the toxin.
- Shellfish should be purchased from a reputable retail store or restaurant.
- Commercially sold shellfish and crab are routinely tested.
- For more information, contact Carol Brady, Alaska DEC shellfish expert.