The U.S. Food and Drug Administration announced June 28 that it is banning imports of five farm-raised fish species from China until shipments are proven to be free of contamination from drugs that are not approved for use in farm-raised fish in the United States. The five banned species are catfish, eel, shrimp, basa (similar to catfish) and dace (similar to carp).

The contaminants include the antimicrobials nitrofuran, malachite green, gentian violet and fluoroquinolone. With long-term exposure, nitrofuran, malachite green and gentian violet have been shown to cause cancer in lab animals. The use of fluoroquinolone in food-producing animals can cause antibiotic resistance. Chinese authorities also prohibit the use of nitrofurans and malachite green in aquaculture.

"The levels of contaminants are low but could cause serious health problems if consumed over a long period of time," said Dr. David Acheson, the FDA's assistant commissioner for food protection, in a telephone press conference. "FDA is taking this action to protect the public health of the American people." But, Acheson added, the low levels of contaminants do not pose an imminent public health threat.

"We're not asking for this product to be withdrawn from the market or for people to take this out of their freezers and throw it away," Acheson said. "This is a long-term health concern. It is not an acute health concern."

China is the world's largest producer of farmed fish, with 70 percent of the total production, and is the third-largest exporter of seafood to the United States, Acheson said. The FDA currently inspects 5 percent of seafood from China.

Natural Foods Merchandiser volume XXVIII/number 8/p. 11