Raw Shellfish Seen as Health Risk : Health: However, data shows that risks of eating seafood, when mollusks are excluded, is very small.

The greatest risk of food poisoning is in eating raw oysters or clams, according to a recent federal advisory.

According to figures developed jointly by the U.S. Food and Drug Administration and the Centers for Disease Control, one out of every 1,000 people who consume raw or undercooked molluskan shellfish--oysters, clams or mussels--may become ill, some seriously. By comparison, one out of every 25,000 servings of cooked chicken is expected to cause an illness.

“Clearly, raw shellfish are the most serious risk that consumers face in the food chain,” said Ellen Haas, executive director of Public Voice for Food & Health Policy. “It is a time bomb ready to go off.”

The risk assessment, released at a recent industry meeting, was intended to calm increasing fears about seafood safety. As such, the data attempt to exonerate fin fish and fully cooked shellfish, which cause acute illness at a much lower rate than that attributed to raw molluskan shellfish.

The risk posed by seafood, when molluskan shellfish are excluded, is actually very small--only one case per every two million servings. This refutes last year’s widely reported claims that seafood was more likely to cause illness than chicken or beef. “The use of these (prior claims) . . . has no scientific basis,” FDA reported.

“Approximately 85% of all acute illnesses from seafood derive from eating molluskan shellfish raw or partially cooked--a very small fraction of all seafood consumed,” said Douglas L. Archer Ph.D, acting director of the FDA’s Office of Seafood, in recent Congressional testimony.

Clare Vanderbeek, vice president of the National Fisheries Institute, an Arlington, Va.-based trade group, says that “commercially available oysters, clams and mussels harvested from approved, certified waters, packed under sanitary conditions and kept properly refrigerated are considered safe for raw, lightly cooked or marinated consumption by healthy individuals.”

Still, the FDA estimates that each year as many as 60,000 people become sick from eating contaminated seafood. Therefore, 51,000 cases can be attributed to raw or undercooked molluskan shellfish. Even these figures are conservative because food poisoning cases are frequently misdiagnosed by patient or physician as flu.

“It is clear that more people become ill eating seafood than is reported in the numbers developed by CDC. However, a precise answer to how many more is impossible to answer,” said Robert E. Bowen, a University of Massachusetts environmental sciences professor who helped author a National Academy of Sciences report entitled “Seafood Safety.”

Haas also said that the FDA’s seafood-related illness estimates are low.

“They are only looking at acute (immediate onset) illnesses and not looking at the long-term risk from chemical contaminants or carcinogens,” she said.

FDA’s Archer said that the agency’ first objective is to control the known “acute” illnesses from seafood. But he added that FDA is also concerned about long-term problems posed by fishery products and is studying the issue.

The primary threat to shellfish is believed to be the spread of pollution from sewage, chemical dumping and pesticide run-off from farm land. However, naturally occurring bacteria also pose a serious threat in oysters, clams and mussels that are consumed raw.

“A large part of the risk associated with raw shellfish comes from organisms not directly tied to coastal human pollution,” said Bowen.

He said that those bacteria posing the greatest risk to shellfish are “not easily limited” by current state and federal seafood inspection efforts. Of particular concern, especially in warm-water locations such as the Gulf of Mexico, are organisms such as Vibrio vulnificus and Vibrio cholera. An increase in the number of illnesses among high risk groups attributed to these related bacteria prompted the California Department of Health Services to require that health warning labels be posed wherever gulf oysters are sold.

The FDA’s Archer said that the agency is taking several steps to improve the safety of molluskan shellfish. These include:

--Development of improved laboratory detection methods for determining water quality.

--A crackdown on the illegal harvesting of shellfish from waters closed by government due to pollution.

--Expanded research into Vibrio bacteria, including differentiation between those strains that are harmful (vulnificus and cholera) and others that are benign.

--A one-year review of all U.S. growing areas for shellfish.

--Developing allowable limits, if any, for chemical contaminants in shellfish. Currently, the FDA has only one binding legal limit for a seafood contaminant: polychlorinated biphenyls or PCBs.

“Short of complete abandonment by consumers of the practice of eating molluskan shellfish without adequate cooking . . . the long-term alleviation of the risk is going to require a major commitment,” Archer said.