Seafood processors undergo FDA safety inspections at least once every two years, but only in plants selling across state lines. In general, it depends on where it comes from, how you prepare it and how often you eat it. In Louisiana and the Gulf Coast, the concern is focused on contamination and natural bacteria in oysters and chemical pollution in waterways. The greatest single risk to seafood consumers, health officials say, is raw shellfish, particularly oysters, mussels and clams contaminated with bacteria and viruses from water polluted with fecal matter or, less commonly, with naturally occurring marine bacteria. The most common cause for closure is fecal matter washed into the oyster beds from urban areas or nearby farmland.
Oysters contaminated with waste can cause cholera and other diseases.
The closures have had a significant effect on oyster production. But other states have it worse than us. Officials in the six states along the Chesapeake Bay, for example, estimate that the region's once world-renowned oysters are at only 3 percent of historic levels, largely because of illnesses that have killed entire oyster beds. Vibrio vulnificus contamination is not related to fecal pollution, officials said, but is found naturally in the Gulf's warm waters. Health officials estimate that as many as 15 people a year are killed by the disease, which can be contracted from eating as few as half a dozen raw oysters.