TUESDAY, May 15 (HealthDay News) -- Up to 56,000 quarantined hogs that ate melamine-tainted feed are to be released for processing and sale after testing revealed their meat poses no harm to humans, U.S. health officials said in an afternoon teleconference Tuesday.

However, an unknown number of farmed fish, as well as 80,000 breeder chickens, are still being held after eating feed or meal that had included melamine-contaminated wheat or rice product originating in China.

"Testing confirms that meat from swine fed ration supplemented with pet food scraps containing melamine and related compounds is safe for human consumption. Therefore it is no longer necessary for these swine to be held on farms. They can be safely sent for further processing," said Dr. Kenneth Petersen, an assistant administrator for field operations at the Food Safety and Inspection Service of the U.S. Department of Agriculture.

According to Petersen, melamine -- a chemical typically found in fire-retardants and plastics -- does not accumulate in pork, because it is filtered out via the animals' kidneys. The hogs in question also appear to be healthy. "Testing also bolsters the conclusion that there is a very low risk of any adverse health effect from consumption of meat from animals exposed to the feed in question," he said.

At the levels of melamine found to be toxic to people, a person would have to eat huge amounts of the tainted meat, Dr. David Acheson, the FDA's assistant commissioner for food protection, said during the teleconference. "A 130-pound person would have to eat more than 800 pounds of melamine-contaminated product a day to reach that level," Acheson said.

Last week, all chickens that were being held were released to market, except for 80,000 breeder birds in Indiana.

Fish fed melamine-laced fish feed are still being held in scores of hatcheries and on two U.S. fish farms, one in Hawaii and the other in Washington, U.S. health officials said.

Last week, Skretting, a company based in Vancouver, Canada, a distributor of melamine-tainted fish food, recalled the feed from 198 U.S. fish farms and hatcheries and 57 Canadian fish farms and hatcheries.

Experts at the U.S. Food and Drug Administration said they still do not know if any fish fed the tainted meal have made it to the U.S. market.

In the meantime, U.S. officials have placed a ban on certain grain products from China, the suspected source of the melamine-contaminated wheat flour, gluten and rice protein that sparked this spring's recall of more than 100 brands of pet food nationwide.

In addition, "all vegetable protein products imported or shipped from China cannot come into the United States unless they have been tested for melamine and other melamine-derived compounds," Acheson announced last week.

The FDA is also sampling pet food imported from China and will begin testing animal feed, including fish feed.

In the United States, the FDA is visiting manufacturers that use imported protein concentrates. The FDA will be collecting samples of both raw ingredients and finished product, and testing them for melamine, Acheson said. "This domestic assignment is targeted at pet food animal food, as well as human food," Acheson noted.

FDA representatives have returned from on-site investigations in China and are writing their report, Acheson said today.

More information

For more information on the pet food recall, visit the U.S. Food and Drug Administration.

SOURCES: May 15, 2007, teleconference with David Acheson, M.D., assistant commissioner for food protection, Office of the Commissioner, U.S. Food and Drug Administration; Kenneth Petersen, D.V.M., M.P.H., assistant administrator for field operations, Food Safety and Inspection Service, U.S. Department of Agriculture

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