TUESDAY, May 8, 2007 (HealthDay News) -- After finding its way to America's dinner tables via pork and chicken, the melamine contaminant in recalled pet food may have also been fed to farmed fish, federal health officials announced Tuesday.
Levels of melamine in the fish are probably far too small to affect human health, stressed officials at the U.S. Food and Drug Administration and the U.S. Department of Agriculture.
The FDA has so far not disclosed which fish farms received the contaminated food, or how many fish, of what type, may have eaten it.
"We have a preliminary list of fish farms, but I can't share it with you," Dr. David Acheson, the FDA's assistant commissioner for food protection, told reporters at a teleconference.
It's also not clear how much of the potentially tainted fish -- if any -- has made it to supermarkets. But Acheson noted that at least one firm's fish had not yet reached a size suitable for sale.
In addition, he said, the contaminated material used in the pet food and imported from China turns out to be wheat flour, not wheat gluten or rice protein concentrate, as had been widely reported.
"We have discovered that the wheat gluten and rice protein was mislabeled," Acheson said. "It actually contained wheat flour contaminated with melamine and melamine-related compounds. These are from the two Chinese firms we have already identified."
Some of the mislabeled wheat flour was shipped first to Canada and then to the United States as fish meal used to feed commercially raised fish, Acheson said.
However, he added, "the levels we are seeing in the fish meal is comparable to that seen in other feed. We have no reason to believe that this is harmful to humans."
Acheson also told reporters that Canadian officials were aware of the contamination. "We used it to make pet food. They used it to make fish meal," he said. Officials said the investigation is ongoing.
U.S. officials have contended that companies in China added melamine, a compound often used to create fire-retardant products, to exported wheat flour, later used in pet food manufacture. The addition of melamine can falsely inflate the protein content in the foods.
Melamine contamination is the prime reason for the massive recall of more than 100 name brands of pet foods in the last two months, following reports of pet illnesses and deaths from liver failure.
Some 2.7 million chickens and 345 hogs have also since been identified as having consumed tainted pet food as part of their feed. Most of the meat from those animals has already been sold to -- and eaten by -- Americans nationwide, health officials say.
Based on a new risk assessment issued Monday, U.S. officials have also lifted a quarantine they had put in place on Friday on almost 20 million chickens that might have gotten tainted feed.
The birds can now be slaughtered and sold to the public, Dr. Kenneth Petersen, an assistant administrator for field operations at the USDA's Food Safety and Inspection Service, said during the teleconference.
"We have no reason to believe that there is any melamine in the meat of these animals," Petersen added.
Federal health officials on Monday had said in a prepared statement that, using the "most extreme risk assessment scenario, "if all the solid food a person ate in one day was contaminated with melamine at the levels found in animals who ate the contaminated feed, the "potential exposure was about 2,500 times lower than the dose considered safe. In other words, it was well below any level of public health concern."
The findings that melamine poses very little risk to consumers was echoed by experts interviewed by HealthDay last week.
"Nothing that has been shown so far is of real [health] concern, as far as human-consumed products go," said Dr. Barry Kellogg, a Florida-based veterinarian and medical director of disaster services at the Humane Society of the United States.
His view agreed with recent statements by officials at both the FDA and USDA.
"We believe the likelihood of a human illness from melamine is unlikely," Acheson told reporters last week. He and other government officials say they have so far turned up no sign of melamine-linked sickness in either humans or in the chickens and hogs fed the contaminated pet food.
To date FDA has only ever confirmed the deaths of 16 pets from contaminated food since the recall began March 16. But the agency has acknowledged that pet owners have reported the deaths of about 1,950 cats and 2,200 dogs. It's not known how many of those were linked to the recalled pet food.
For more information on the pet food recall, visit the U.S. Food and Drug Administration.