MONDAY, April 30 (HealthDay News) -- U.S. health officials continued to reassure American consumers that pork products from hogs fed contaminated pet food were safe, even as reports surfaced that China has routinely added the contaminant melamine to its exported animal food supplements.

In a joint statement issued late Saturday, the U.S. Food and Drug Administration and the U.S. Department of Agriculture (USDA) stressed, "We are not aware of any human illness that has occurred from exposure to melamine or its by-products." They added that they have also identified no illnesses in swine fed the salvage food tainted by melamine, which was imported from China as an additive to wheat gluten used in dog and cat food.

Melamine, a derivative of coal, is at the center of the United States' largest pet food recall, involving more than 60 million packages of 100 name-brand products. The chemical has been linked to the deaths of at least 16 pets and the illness of possibly thousands of pets.

The USDA first announced on Thursday that meat from 345 hogs suspected of eating the contaminated feed had entered the U.S. food supply. Some 6,000 hogs suspected of eating the contaminated product have since been quarantined and meat from these animals would be withheld from the food supply, both agencies said.

In the Saturday statement, the FDA and the USDA said the possibility of human illness from eating swine exposed to melamine remains low for several reasons: "First, it is a partial ingredient in the pet food; second, it is only part of the total feed given to the hogs; third, it is not known to accumulate in the hogs, and the hogs excrete melamine in their urine; fourth, even if present in pork, pork is only a small part of the average American diet."

On Monday, The New York Times reported that Chinese producers routinely add melamine to wheat gluten and rice protein in animal feed products to falsely inflate levels of protein.

In interviews with agricultural workers and managers in China, the newspaper reported that animal feed producers have secretly added melamine to their feed for years because, during tests, it appears to be a protein, even though it doesn't add any nutritional benefits.

"Many companies buy melamine scrap to make animal feed, such as fish feed," Ji Denghui, general manager of the Fujian Sanming Dinghui Chemical Company, which sells melamine, told the Times. "I don't know if there's a regulation on it. Probably not. No law or regulation says 'don't do it,' so everyone's doing it. The laws in China are like that, aren't they? If there's no accident, there won't be any regulation."

On Thursday, China banned melamine from its food products, but rejected the charge that the substance caused the U.S. pet deaths, the Associated Press reported.

It's not clear why melamine became so fatal in pet food, because it's not believed to be particularly toxic. But U.S. law bans its presence in any form of food, the newspaper said.

The rice protein was imported to the United States by Wilbur-Ellis, an agricultural product importer and distributor. The FDA said it is continuing its investigation of the source of the adulterated pet food, including "tracing products distributed since August 2006 by Wilbur-Ellis throughout the distribution chain."

In their latest statement, the FDA and the USDA said that, as of April 26, they had identified sites in six states where contaminated pet food was received and used in feed given to hogs: California, Kansas, New York, North Carolina, South Carolina and Utah.

On Friday, FDA officials searched the facilities of a pet food manufacturer and one of its suppliers in the continuing probe of the contamination, the AP reported.

The officials searched an Emporia, Kan., pet food plant operated by Menu Foods and the Las Vegas offices of ChemNutra Inc., the news service said, citing information supplied by the companies.

Menu Foods made many of the major brands of dog and cat foods that were recalled because of the melamine-contaminated wheat gluten. ChemNutra supplied Menu Foods with the wheat gluten, which was also imported from China but reportedly from a different supplier than the rice protein.

Both companies said they were cooperating with the investigation, the AP said.

Meanwhile, the USDA will compensate hog farmers affected by the tainted pet food, Kenneth Peterson, an assistant administrator for field operations at the USDA Food Safety and Inspection Service, said during a Thursday teleconference.

"The pork and pork products from these animals will be destroyed," Peterson added. Each year, more than 105 million hogs are slaughtered in the United States, the AP said.

More information

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

SOURCES: April 28, 2007, joint statement, U.S. Food and Drug Administration and U.S. Department of Agriculture; April 26, 2007, teleconference with Capt. David Elder, director, Office of Enforcement Office of Regulatory Affairs, FDA, and Kenneth Peterson, assistant administrator, field operations, Food Safety and Inspection Service, USDA; The New York Times; Associated Press

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