Food Safety Facts on Paralytic Shellfish Poisoning (PSP)

Shellfish are nutritious foods that may be enjoyed in a variety of ways. However, consumers should be aware of some potential food safety issues associated with certain products such as bivalve shellfish (clams, oysters and mussels) as well as the tomalley of lobster and crab.

Bivalve shellfish are highly sensitive to the quality of their marine environment. They eat microscopic plants that can produce marine biotoxins, which build up in their tissues. There are different biotoxins of concern in Canadian waters: domoic acid, which is associated with Amnesic Shellfish Poisoning (ASP); toxins which cause Diarrhetic Shellfish Poisoning (DSP); and saxitoxin, which is linked to Paralytic Shellfish Poisoning (PSP).

What is PSP?

• PSP is an illness that may have serious and potentially fatal effects for some people
• PSP is caused by eating bivalve shellfish such as oysters, clams, scallops, mussels and cockles; non bivalve shellfish such as whelks; and tomalley (also called hepatopancreas, which is the soft green substance inside the body cavity) of crustaceans such as crabs and lobsters; that contain high levels of marine biotoxins.
• There is no known cure for PSP

What are the symptoms of PSP?

• Symptoms of PSP could begin within a few minutes and up to 10 hours after consumption.
• Symptoms of PSP include a tingling sensation or numbness around the lips. This gradually spreads to the face and neck. Other symptoms include a prickly sensation in the fingertips and toes, headache and dizziness.
• In more severe cases one may also experience incoherent speech, a prickly sensation in the arms and legs, stiffness and non-co-ordination of limbs, weakness and a rapid pulse. Respiratory difficulty, salivation, temporary blindness, nausea and vomiting may also occur.
• In extreme cases, paralysis of respiratory muscles may lead to respiratory arrest and death within two to 12 hours after consumption.
• Seriously affected persons must be hospitalized and placed under respiratory care.

Where could I come into contact with biotoxins linked to PSP?

• PSP illness is linked to the consumption of contaminated shellfish. The toxins that cause PSP are not destroyed by cooking.
• The tomalley of crustaceans, such as crabs and lobsters, which have fed on contaminated bivalve shellfish may also contain PSP toxins. There have not been any confirmed cases of PSP illness in Canada from consumption of lobster or crab tomalley.
• Shellfish can have high levels of marine toxins during any given month depending on environmental conditions. If you are harvesting shellfish recreationally, it is important that you ensure the area is open and safe for shellfish harvesting.

What can I do to protect myself and my family?

• Shellfish should be purchased from a reputable retail store or restaurant.
• Only shellfish harvested from open harvest areas should be consumed.
• Caution is required when harvesting shellfish. It is your responsibility to contact your nearest Fisheries and Oceans Canada (DFO) office to find out which areas are assigned as "open" for shellfish harvesting. An "open" area refers to a safe harvest area that is subject to monitoring and testing, and where harvesting is a legal activity. When an area is officially "closed," it is illegal to harvest shellfish in that area for any purpose.
• Updates on the opening and closing of harvesting areas are communicated to the public though local media, notices posted in closed areas, and information provided by local DFO offices.
• Note that properly cooked shellfish can still be toxic since PSP toxins are not destroyed by cooking.
• Anyone who feels ill after eating shellfish should seek the advice of a health care professional and should contact their local public health unit.
• Health Canada advises Canadians to limit their consumption of lobster tomalley, to the equivalent of one lobster tomalley daily for adults, due to the possible presence of PSP. Health Canada has recommended that children not consume lobster tomalley. The consumption advisory can be found on their website at http://www.hc-sc.gc.ca/ahc-asc/media/advisories-avis/_2009/2009_45-eng.php
• PSP can also occur in other countries. Tourists should be cautious when consuming shellfish abroad.

What is the federal government doing regarding the safety of shellfish for human consumption?

• Health Canada establishes all food safety guidelines for bacteria, toxins, and other contaminants in foods.
• The federal government established the Canadian Shellfish Sanitation Program (CSSP) to ensure that shellfish harvested in Canada are safe to eat. Three federal government agencies work together to deliver this program:
  • Environment Canada analyzes water quality in shellfish harvesting areas and identifies waters that do not meet sanitary standards.
  • The Canadian Food Inspection Agency (CFIA) monitors for biotoxins in shellfish in harvesting areas and is responsible for registering and inspecting fish and shellfish processing plants.
  • DFO patrols and closes harvest areas, and bans the harvesting of shellfish whenever bacteria or toxin levels exceed safety standards.
• Under the CSSP, shellfish samples are taken directly from shellfish growing areas and are regularly analyzed for ASP, DSP and PSP toxins. Hundreds of sites in Atlantic Canada, Quebec and British Columbia are regularly tested for these toxins.

Click here for more information on ASP, DSP and harvesting bivalve shellfish in Canada. Visit the CFIA's website at www.inspection.gc.ca to learn more about foodborne illness and safe food handling practices.

To find out which bivalve shellfish harvesting areas are open, call your nearest DFO office listed in local telephone directories.

P0034E-03/07
March 2009