Drug Traces Prompt Closer Look at Farmed Seafood

By Cat Lazaroff

WASHINGTON, DC, June 17, 2002 (ENS) - The Food and Drug Administration has boosted its sampling of imported shrimp and crawfish over concerns that the products may be contaminated by a powerful antibiotic. Low levels of the drug, chloramphenicol, have been detected by some states and other countries.

A farm raised shrimp in China. (Three photos by Dr. James McVey, NOAA Sea Grant Program)

This spring, the EU banned or recalled certain food products from China and Vietnam found to be contaminated by chloramphenicol at these low levels.

Chloramphenicol is a potent, broad spectrum antibiotic drug used only for treatment of serious infections in humans. The drug has known side effects, including an increased risk of certain cancers and other diseases, such as leucopenia, anemia and aplastic anemia.

Due to the unpredictable effects of dose on different patient populations, the FDA says it has not been possible to identify a safe level of human exposure to chloramphenicol, so federal regulations prohibit its use in farmed animals and animal feed products.

Aquaculture tanks in China, 1991.

"The FDA is concerned about any detection of chloramphenicol in shrimp and crayfish, " said Dr. Lester Crawford, FDA deputy commissioner. "The agency will take whatever action is necessary to protect the public health."

The FDA has been using a test that could detect chloramphenicol in shrimp down to a five parts per billion (ppb) concentration, though Canada and the EU had refined their methods to detect even lower levels. The FDA has now modified its methods to confirm chloramphenicol levels in shrimp and crayfish down to one ppb, and plans to lower that limit to 0.3 ppb in the near future, matching the methods used by Canada and the EU.

The FDA says it will seize and hold any product it identifies and confirms as containing chloramphenicol.

Kuruma prawns in an aquaculture observation tank.

Earlier this month, a senior delegation of Chinese officials met with the FDA to discuss the issue of chloramphenicol residues in shrimp and crayfish. On March 5, China banned the use of chloramphenicol in animals and animal feeds, the delegation told the FDA.

China also announced that they are beginning to test shrimp, crayfish and other animal foods headed for export to confirm they contain no drug residues.

A shrimp farm in Arizona. U.S. aquaculture facilities are barred from using dangerous antibiotics like chloramphenicol. (Photo courtesy National Oceanic and Atmospheric Administration)

The EU has also found chloramphenicol in shipments of shrimp from Myanmar, India, Pakistan and Vietnam.

About one in every four fish and one in every three shrimp consumed around the world now come from aquaculture farms. By the year 2007, experts predict that more than half of the world's seafood supply will come from aquaculture, making it increasingly important to regulate the chemicals used in fish and shrimp farming.