Get hooked on seafood safety – includes related information on how to tell if a fish is fresh

Get hooked on seafood safety – includes related information on how to tell if a fish is fresh – Cover Story

Roger W. Miller

What food is nutritious, wholesome, tender, easy to digest, and yet subject to a bad press? The answer: seafood.

Yes, despite its growing popularity in a country in which counting cholesterol has become almost an important as counting calories, seafood has often been pictured in the media as unsafe. Last year, for example, editorial writers for the New York Times, Washington Post, Atlanta Constitution, and the Dallas morning News all quoted statistics claiming that eating fish was 25 times more likely to make you ill than dining on beef and 16 times more likely than downing poultry or pork. Both CBS TV’s “This Morning” program and TV station WABC in New York City repeated those statistics in features on fish safety.

The editorial writers and the TV producers also called for new legislation to provide more government inspection of fish so that we’d be better able to keep down our seafood.

All of which caused then Acting FDA Commissioner James S. Benson to tell the New York Times in a letter to the editor: “You have been severely misled.”

Supporting Benson was a report last January from the National Academy of Sciences. Completing a two-year study of seafood safety, the academy concluded: “Most seafoods available to the U.S. public are wholesome and unlikely to cause illness in the consumer.”

The statistics used by the editorial writers applied to “outbreaks” of illnesses reported to the national Centers for Disease Control in Atlanta, the federal agency responsible for collecting and analyzing health statistics. (An outbreak is two or more illnesses linked to a common source.) The news people failed to pick up the distinction between outbreaks and illnesses, and failed to appreciate that CDC only tabulated those incidents reported voluntarily by state and local health authorities. These authorities tend to report only major incidents, such as outbreaks involving two or more people.

To get a truer picture of the safety of seafood, FDA’s Center for Food Safety and Applied Nutrition, in cooperation with CDC, did a risk assessment study. It showed about one illness per million servings for seafood when raw or partially cooked molluscan shellfish (mussels, scallops, clams and oysters) were excluded from the calculations. (In comparison, the risk assessment for chicken is about one illness for every 25,000 servings.)

Beware Raw Mollusks

Now add raw mollusks to the statistical stew an, as Hamlet said: “Ay, there’s the rub.” According to the FDA risk assessment, the chance of illness for seafood overall with the raw shellfish jumps to something like 1 in 250,000 servings. That’s still 10 times safer than eating chicken, but the agency figures that those raw oysters, clams and mussles–so savored by gourmets–account for a whopping 85 percent of all the illnesses caused by eating seafood.

Mollusks are troublemakers because most common move and have to feed by filtering water through their systems, pulling out nutrients in the process. In so doing, they also can pick up and store harmful bacteria and viruses that can cause a string of illnesses. When people eat these pathogen-packed shellfish raw they ingest the viruses and bacteria.

Or, as Anthony Guarino, director of FDA’s fishery research branch on Dauphin Island, Ala., asks; “What other animal do we eat, digestive track and all, without cooking it first?”

These mollusks have long been consumed raw by humans, and no doubt they have made people ill throughout history. However, the threat they pose today may be greater because of increase pollution of the waters in which they live. Mollusks are usually found in estuaries, which is where rivers and seas meet. And estuaries these days are more likely to be closer to cities and thus more apt to be polluted than offshore waters.

FDA’s risk assessment study concluded that 1 out of every 1,000 to 2,000 servings of raw mollusks is likely to make someone ill. For that reason, these shelled creatures could stand a little more press attention. Not enough people realize the danger in eating them uncooked, particularly when they are taken from contaminated warmer waters or held and shipped without adequate refrigeration. The warmer the temperature, the quicker the bacteria multiply.

Two states–Louisiana and California–now require warning notices about eating raw shellfish at places where they are sold. In Louisiana, the following notice is required:


Raw oysters, raw clams, and raw mussels can cause serious illness in persons with liver, stomach, blood or immune disorders.

The California notice requires a similar tag on the scak or container of oysters from the Gulf of Mexico. The message is much the same. That state specifies that retail establishments must display the notice in signs, menu warnings, table tents, or “other visible warnings at point of sale….”

Oysters taken from the Gulf of Mexico, particularly from March through October, may contain naturally occurring pathogen called Vibrio vulnificus, which is particularly pernicious to persons with liver disease, such as heavy drinkers. Cancer patients, people with iron metabolism disorders, and those with weakened immune systems (such as AIDS victims) may also be vulnerable. The risks are high. The fatality rate for at-risk individuals who become infected is more than 50 percent, with death usually occurring within two days.

(For more on Vibrio vulnificus, see “Fewer Months ‘R’ Safe for Eating Raw Gulf Oysters” in the june 1988 FDA Consumer.)

While raw or undercooked shellfish continues to pose problems, the fact that, overall, seafood is a safe and nutritious part of the diet means that it’s likely Americans will continue to put more seafood on their forks in the coming years. Indeed, the National Fisheries Institute, a trade organization, has set a goal of 20 pounds per citizen by the year 2000. Seafood consumption in 1989 was figured at 15.9 pounds per person, not including recreationally caught fish (which adds another 3 to 4 pounds per person). That was an increase in consumption of commercially caught fish of 25 percent since 1980. These increases occurred while beef and pork consumption declined (poultry eating also gained). All of which probably reflects health concerns of consumers.

FDA Steps Up Programs

Reflecting this growing preference for fish, FDA has stepped up its programs to ensure the safety of seafood. Last March, the Office of Seafood was created within the agency’s Center for Food Safety and Applied Nutrition to strengthen the agency’s domestic and imported seafood programs. The office will reinforce the agency’s mandate to conduct enforcement, research, educational, and training activities on seafood. Creation of the new office was announced in a Federal Register notice published Feb. 26, 1991. Nationwide, FDA presently has some 300 people engaged in various seafood safety programs. An additional 270 scientific and inspectional staff positions will be added to the program over the next two years. Congress has authorized approximately $9.5 million for 122 new positions for seafood programs in the current fiscal year, and FDA has requested another $ 15 million for 150 more positions for the 1992 fiscal year beginning Oct. 1.

The responsibilities of the new Office of Seafood include:

* overseeing seafood inspection programs undertaken by FDA in cooperation with other federal and state agencies

* researching and testing methods to detect and evaluate the effects of chemical and microbial contaminants that may present public health hazards in fish caught in the ocean and coastal waters, and in seafood products developed through aquaculture

* developing methods to identify economic fraud

* administering the National Shellfish Sanitation Program, which works to maintain the safety of shellfish

* evaluating the effectiveness of the agency’s seafood initiatives

* participating in programs to increase industry awareness of FDA seafood regulations and enforcement programs

* overseeing the development of training programs in seafood safety for FDA, state and local inspectors. This would result, in part, in upping the number of FDA shellfish specialists from 12 to more than 50.

Together with the states, FDA is developing a program to more comprehensively monitor waters from which fish and shellfish are taken, and, in March, FDA announced that it had launched a special inspection of the nation’s seafood processing plants and other seafood establishments and has begun the first of several pilot programs aimed at further ensuring the safety and quality of seafood through surveillance from ship to final sale.

FDA plans to complete its special inspection of all seafood establishments listed with the agency within the year to get a picture of the state of current seafood handling and any new or generalized problems in the various parts of the industry.

The new pilot program is a cooperative effort with the National Marine Fisheries Service (NMFS) of the Department of Commerce. It applies the techniques of identifying and controlling critical processing points (a system called Hazard Analysis Critical Control Point methods), which FDA has already applied with great success to the canning industry.

FDA also is strengthening its work with the coastal states and NMFS, aimed at making criminal cases against “shellfish bootleggers,” who harvest and sell shellfish illegally from contaminated waters.

In announcing the inspection program, Assistant Secretary for Health James O. Mason, M.D., explained, “These new programs do not mean that fish are not safe food. What these new programs do mean is that FDA is enhancing its seafood inspection program to keep up with this increasingly important part of the American diet.”

Mason said the Institute of Medicine backed the kind of regulation FDA and NMFS are trying in their pilot program with eight seafood processors–with representative facilities producing fin fish, crab, surimi (fish processed to taste like lobster or other shellfish), and other specialty products.

In these plants, what are known as “critical control points” have been identified. These are points in the process where problems can arise. The firms will monitor and record data at each of these points for review and inspection.

Mason said participating firms will eventually have a special seal with which to label their products–and it will be up to consumers to demand the new system when they buy.

Pilot projects are also planned soon to bring Hazard Analysis Critical Control Point principles to shellfish, as well as imports and retail operations.

The stepped-up programs also include more oversight of imported fish products (more than half of the fish Americans consume is imported) and of the fast-growing aquaculture industry. (Some 360 million pounds of catfish alone were grown on U.S. “fish farms” in 1990.)

Other Seafood Sicknesses

In addition to molluscan shellfish, the other popular raw fish dish, sushi, may also present dangers to the diner. Larvae of parasites–including roundworms, tapeworms, flukes, and flatworms–can end up in the meat of fish. Symptoms are usually mild and temporary, but in a few cases severe abdominal pain can result. If you want to eat sushi, find out if the fish was previously frozen, as freezing kills the larvae. Consumers should not prepare sushi at home.

More common among the seafood maladies are illnesses traced to the Norwalk virus and the naturally occurring scombroid and ciguatera poisonings. While Vibrio vulnificus is the No. 1 killer among seafood pathogens in immune-compromised individuals, the Norwalk virus causes most illnesses that result from eating molluscan shellfish.

Gastroenteritis (inflammation of the stomach and intestines) is the characteristic symptom of the Norwalk virus infection. The virus comes from fecal contamination of waters where the mollusks live. Those polluted waters are the ones that authorities try to detect and close down to harvesters. However, some water men may work the areas anyway and offer their “bootlegged” products to the public.

Human sewage can also contain bacteria that cause cholera and other illnesses, and mollusks can pick up those microbes. While cholera has been all but wiped out in waters around more developed countries, it is almost a constant in some Third World areas and has been a particular problem for some South American countries this year.

Yet another legacy of untreated sewage that finds its way into shellfish is the virus that causes hepatitis A. The symptoms are relatively mild, but some people can be left with severe liver damage.

Two other diseases that can result from consuming shellfish–even if well cooked–are paralytic shellfish poisoning (PSP) and neurotoxic shellfish poisoning (NSP). Both are caused by naturally occurring toxins. PSP can be fatal but both it and NSP are extremely rare, thanks to excellent monitoring programs. Symptoms can appear within 30 minutes of ingestion; they include tingling, numbness or burning sensations in the lips, gums, tongue, and face. NSP is similar to PSP but milder. Symptoms include tingling in the extremities, vomiting and diarrhea.

Both NSP and PSP occur in humans after they’ve eaten mollusks that have fed in some “bloomed” waters. These blooms, more commonly known as “red tides,” contain plankton (dinoflagellates) in such numbers as to discolor the water. The plankton aren’t toxic to the shellfish, but may be dangerous to humans. Not all “blooms” contain toxic dinoflagellates, but when they do the shellfish may be carrying the plankton several days before the water changes color.

A few species of fin fish can also be the source of illness even if thoroughly cooked. Dinoflagellates can also cause ciguatera poisoning, although the plankton doesn’t need to be present in such numbers as to add hues to the water. Found mostly in warmer waters, the toxic plankton moves up the food chain to predatory reef fish, notably groupers, snappers, baracuda, and Spanish mackerel. Ciguatera causes an estimated 30 percent of all fin fish-borne food poisonings in the United States, some 3,000 cases annually. Most cases occur in Hawaii, Guam, Puerto Rico, and the Virgin Islands. Many cases occur when sports fishermen sell their catch to restaurants; commercial fishermen avoid such reefs.

Symptoms are called “moderately severe,” affecting both the gastrointestinal and neurological systems. The symptoms, which can occur almost immediately, include diarrhea, nausea, vomiting, chills, and sweating.

FDA hopes to test a kit that could detect ciguatera contamination this year.

Scombroid poisoning is usually associated with tuna, bluefish and mahi-mahi (dolphin fish). These fish naturally contain high levels of histamine, which is released as the fish decompose. The disease runs its course, and the usually mild symptoms include nausea, vomiting, diarrhea, rash, and tingling and burning sensations around the mouth.

Sports Fishing

Ciguatera and scombroid poisonings point up another area of concern for health officials–recreational fishing. It’s estimated that people casting lines in water and digging clams along the seashore may add 3 to 4 pounds to the nearly 16 pounds of seafood that each American, on average, consumes each year. The reef fish associated with ciguatera are prized by sport fishers, as are the scombroid-susceptible bluefish and, to a lesser extent, tuna.

State health officials often issue advisories to warn anglers of the poisoning possibilities in the fish they catch and to caution them against trying to sell such disease-prone fish to vendors or the public.

Sport fishers also need to be careful about doing their thing in waters contaminated by chemicals and metals. These contaminants may include pesticides (such as DDT and dioxin), mercury, and PCBs (polychlorinated biphenyls). The latter were widely used in the past as insulators in transformers and were generously dumped into any convenient body of water after use.

Mercury (or, more correctly, the form known as methylmercury) and PCBs are the main pollution problems. Both can cause birth defects, and both have been the subject of numerous advisories to anglers. (Swordfish are particularly known for accumulating methylmercury, and consumption of that fish on a regular basis may not be advisable for women who are pregnant or likely to become pregnant.)

In its recent report, the Nationa Academy of Sciences concluded that “only a small portion of seafood is contaminated with appreciable concentrations …” of chemicals. But the academy cautioned that the area had not been studied well enough, and it called for better efforts to alert fishermen and the rest of the public about contaminated waters.

What Consumers Can Do

While FDA is working to ensure that the seafood sold to the public is safe, consumers themselves can do a lot to make sure that their seafood doesn’t cause illness. Indeed, it is estimated that as much as half of all seafood problems could be eliminated by better handling and preparation in the home and in restaurants and other food service establishments. Two accompanying articles give tips on how to select and store seafood.

As to seafood preparation, the household chef can’t go wrong by following good sanitation practices, such as washing hands thoroughly before starting to prepare a meal and after handling foods–such as meat and fish–that contain bacteria, keeping equipment such as knives and cutting boards clean, and keeping hot foods hot and cold foods cold. (For more on safe food preparation, see “The Unwelcome Dinner Guest: Preventing Food-Borne Illness” in the January-February 1991 FDA Consumer.)

Sufficient cooking is most important of all when it comes to seafood safety. Fish is done when it is no longer translucent, when it flakes easily with a fork. Oysters and clams should be placed in boiling water, and then cooked for four to six minutes after the water begins to boil again, or steamed for six to eight minutes. Virtually all bacteria and other harmful agents will be killed with proper cooking.

Seafood lovers who can’t live without raw shellfish would be wise to limit their consumption to the cold weather months, when the mollusks are less likely to be carrying disease-causing organisms. Always buy from a reputable dealer. Roadside stands that offer low prices may be offering “bootleg” shellfish–that is, shellfish taken from off-limit (polluted) waters. Shellfish shippers have to meet federal standards and are certified by state shellfish control authorities.

So what’s the bottom line on eating seafood? For the most part, seafood is wholesome, nutritious, easy to prepare and digest, best eaten when fully cooked–and safe.

Roger W. Miller is a writer in Chevy Chase, Md., and a former editor of FDA Consumer.

COPYRIGHT 1991 U.S. Government Printing Office

COPYRIGHT 2004 Gale Group