Raw Molluscan Shellfish
Bivalve molluscan shellfish like clams and oysters are commonly eaten raw or partially cooked. Because of where they live, how they feed, and how they’re eaten, these shellfish can contain bacteria or viruses that can cause illness. Bivalves live close to the shore in waters which may be contaminated with bacteria and viruses from runoff or from land or sewage discharges. These shellfish obtain food by pumping water through their system and filtering out small organisms. As a result, their digestive system, which is one of the parts that we eat, can contain bacteria and viruses from the waters in which they live. These microorganisms can then be ingested if the shellfish are eaten raw. For this reason, certain people should avoid eating raw or partially cooked shellfish including: young children, females who are pregnant or nursing, immune-compromised individuals, and older adults.
Shellfish Safety Programs
The FDA and coastal state governments oversee the National Shellfish Sanitation Program that sets standards for shellfish growing waters and the harvesting, handling, processing and distribution of clams, oysters, mussels and whole scallops. This system is designed to ensure that shellfish are harvested from certified waters that meet safety standards. It also requires that all shellfish be properly tagged and that all firms who handle shellfish be licensed and that their facilities and operations meet appropriate sanitary standards. This program has helped protect consumers for many years, and large amounts of raw clams and oysters are consumed without incident.
Tips to Minimize Risk
The following tips can help those who choose to eat raw or partially cooked shellfish, including clams, oysters and mussels, manage or reduce potential risks associated with this unique type of seafood product. These tips do not necessarily apply to other types of crustacean shellfish like shrimp, crabs or lobsters, which are usually cooked before they are eaten.
- Buying: Always buy clams, oysters, and mussels from a reputable dealer.
- Use caution if you harvest bivalve shellfish yourself. Obey posted warnings and check with local authorities to verify that the waters are certified for shellfish harvesting before you harvest them or decide to eat them.
- Don’t eat dead shellfish whose shells don’t close tightly when tapped or agitated. (Some shellfish like soft-shell clams can’t completely close their shell, but should move when touched.)
- Handle and store shellfish properly. Keep live shellfish cool and damp in the refrigerator. Rinse when necessary to remove dirt or debris, but avoid prolonged contact with fresh water, drastic temperature changes, and airtight containers. Don’t allow other foods, containers, utensils, or food handlers to contaminate or drip on them during storage, and when preparing or serving them.
- High risk individuals who are more likely to become seriously ill from bacteria and viruses should avoid raw or partially cooked shellfish. This includes pregnant women, young children, older adults and people with compromised immune systems that have conditions like: cancer (especially during chemotherapy), liver disease, diabetes, chronic kidney disease, HIV infection and people with decrease stomach acidity or disorders of the digestive system.
- Cook shellfish properly to further reduce potential risks. Oysters, clams, and mussels should be cooked in small batches so that those in the middle are cooked thoroughly. To cook live shellfish properly follow these suggestions. When steaming, cook for 4 to 9 minutes after the start of steaming. When boiling, after the shells open boil for another 3 to 5 minutes. Shucked products should be boiled for 3 minutes, or fried at 375°F for at least 3 minutes or baked at 450°F for 10 minutes.
Adapted from: Seafood Savvy by Ken Gall, New York Sea Grant and Cornell University
Ready-to-Eat Seafood Products
Products that that may not be fully cooked before they are eaten are often called Ready-to-Eat or RTE food products. These products can be made from all of the major high protein perishable foods including meat, poultry, dairy and seafood. RTE foods must be refrigerated properly to prevent the growth of harmful bacteria that could cause food borne illness and they must be handled properly during storage, preparation and serving.
Examples of RTE seafood products that must be refrigerated and may not be cooked before they are eaten include:
|Sushi or sashimi||Smoked seafood||Seafood salads or dips|
|Cooked shrimp, crab or lobster meat||Pasteurized seafood||Pickled seafood|
|Ceviche or raw marinated seafood||Dried seafood||Seafood sandwiches|
Proper Handling Is Important
The key to handling these foods safely is to keep them cold and get them home as quickly as possible, keep them refrigerated, prevent contamination during storage, preparation, and serving, and limit the amount of time that they are exposed to room temperature. Safe handling tips include:
- Keep It Cold!
Keep RTE seafood products below 40°F. Pick up RTE seafood last during a shopping trip and transport it home in a cooler or other insulated container with ice or gel packs. Check the temperature of your refrigerator with a thermometer to make sure it is below 40°F. Thaw frozen products in the refrigerator. If the RTE seafood is going to be exposed to room temperature for more than an hour or two, serve it on ice.
- Keep It Clean!
Make sure that raw foods don’t drip, splash or touch RTE foods when transporting them home or while storing them in the refrigerator. Store them in sealed plastic bags or containers if necessary. Use a clean cutting board and utensils when preparing them for serving, and clean serving dishes, trays or platters.
- Use RTE Foods as Soon as Possible! Dont use products that have exceeded a “Use By” or other date that is designed to indicate its predicted shelf life. When in doubt, cook the product thoroughly before using it or throw it out.
Use Caution When Serving These Products to Some Individuals
Some people may be at increased risk for serious complications when exposed to certain kinds of bacteria that can cause food borne illness. High risk individuals include those who may have a compromised or weak immune system because of health conditions such as liver disease, cancer or chemotherapy patients, HIV infection, stomach or intestinal problems, and certain groups such as the elderly, pregnant women and young children. These individuals should use caution and consider whether or not to they should eat RTE foods unless they are cooked properly before consumption. Pregnant women should use special caution because of potential severe risks to themselves and their unborn baby that are associated with a type of bacteria called Listeria that could be present in some RTE food products.
Click Here to view the Food and Drug Administration publication, Special Handling for Ready-to-Eat, Refrigerated Foods To Reduce the Risks of Foodborne Listeria
Recreationally Caught Fish and Shellfish
Fish and shellfish are unique foods in that large amounts are harvested by individuals for their own personal consumption. It is estimated that one-fifth of the fish and shellfish eaten in the U.S. comes from recreational or subsistence fishing in the ocean, in marine bays or estuaries, or in freshwater lakes, ponds, rivers or streams.
Food Safety Issues
Individual fishermen may catch fish from waters that are known to contain elevated levels of contaminants or pollutants like PCBs or pesticides, even though commercial fishing in these waters is banned. The presence of environmental contaminants from certain areas can cause long term health effects if fish and shellfish from these areas are consumed. Repeated exposure to these chemicals over time may affect reproduction, growth and development in children, and may increase lifetime cancer risks. Pregnant women and children who eat large amounts of sport caught fish from contaminated waters are at greatest risk. State health authorities issue fish consumption advisories that advise all anglers and high risk individuals to limit their consumption of certain types of fish or fish of a particular size from specific bodies of water. These advisories may be distributed with fishing licenses in some states or can be found on the website of the state health authority. The U.S. Environmental Protection Agency has a Website with links to each state’s fish consumption advisories. Click here to view this site.
Naturally occurring toxins are sometimes produced in the marine environment. These toxins are usually associated with certain kinds of fish or shellfish that come from specific geographical areas. For example, the toxin known as ciguatera is associated with certain types of reef fish from specific tropical areas. These toxins are not destroyed by cooking, so potential risks can best be managed by exercising caution when eating recreational fish or shellfish from unfamiliar waters and checking to make sure that there are no local advisories.
Another type of toxin, called scombrotoxin, is caused by improper fish handling. Scombrotoxin is produced when certain species of saltwater fish like tuna, mackerel, bluefish, mahi-mahi, and amberjacks begin to spoil. When these fish are exposed to temperatures that allow rapid bacterial growth, histamine is formed which can cause an allergic-type reaction when the fish is eaten. This toxin is not destroyed by cooking, but it can be prevented by properly handling and cooling these types of fish. This toxin can be rapidly produced when fish are allowed to remain in warm water or on the deck of a fishing boat or dock for several hours in warm weather. Recreational fisherman should plan ahead and have plenty of ice available to get these fish as cold as possible as soon as they are taken out of the water and keep them cold until they are safely stored in the home refrigerator.
Tips to Manage Risks That Could be Associated with Recreational Fish or Shellfish
The following guidelines can help recreational anglers and the people who eat these fish manage potential safety risks:
- Before you go fishing, check to see if there are any health advisories for the body of water or type of fish or shellfish that you intend to catch. Advisories are available from local or state health departments, fisheries agencies, or you can check the EPA Website.
- To minimize risks associated with chemical contaminants or toxins do not eat excessive amounts of any single type of fish or shellfish from contaminated waters and do not eat the internal organs of fish, the tomalley of lobsters, or the mustard in crabs. These organs can contain significantly higher amounts of contaminants or toxins.
- Individuals at greater risk for exposure to chemical contaminants, including pregnant women, women of child bearing age, and children under age 15, should take special care to avoid species known to have elevated levels of contaminants.
- If you choose to eat sport fish that may contain elevated levels of chemical contaminants, trim away fatty areas (for example the skin and belly area) and use cooking methods like baking or broiling that allow fats and juices to drain away.
- Plan ahead to keep the fish you catch cold. Bring enough ice to completely surround the fish and a cooler to keep the ice from melting so the fish will stay cold.
- Use clean drinkable water when rinsing or cleaning your catch and keep all cutting boards, knives and other equipment clean.
Adapted from: Seafood Savvy by Ken Gall, New York Sea Grant and Cornell University