Federal health inspectors in the U.S. are still stressing that the threat from pet food-tainted animal feed is minimal to humans, but caution that they expect to find more farms where hogs and poultry have consumed the tainted product.
Investigators are still trying to get a grasp on how far the melamine-contaminated pet food crept into the animal feed system.
The FDA investigators announced on Monday that chicken feed containing byproducts from the tainted pet food had been used on Indiana farms.
A few days before that, they said farms in six states may have received tainted pet food to use as chicken feed.
The Associated Press reports that the tainted pet food in question could be to blame for the wave of dog and cat deaths in March due to kidney failure, but FDA officials say the risk to humans and livestock is minimal.
"The thing with melamine is that it's known to be very non-toxic. There's been very little research done on it because it is rather harmless," said Dr. Gary Weaver, director of the program on agriculture and animal health policy for the University of Maryland's Center for Food, Nutrition, and Agriculture Policy.
"It's my understanding this is one of the reasons that the Chinese small producers have been putting it in the feeds. It gives a false high reading for protein but doesn't do any harm," Weaver told Â鶹´«Ã½net.
Officials at the Canadian Food Inspection Agency said the agency was keeping a close eye on the U.S. situation, but had no reason to believe there was any risk in Canada.
A CFIA official told CTV.ca the slaughtered hogs and chickens were believed to have been distributed within the U.S. only.
However, the official pointed out that the probe of the affected poultry is still underway, and there is a slight chance the investigation will be widened to Canada.
Dr. David Acheson, an FDA assistant commissioner, told AP that because the tainted product only represented a small portion of the food the poultry was fed, and poultry represents only a small portion of most humans' diet, there is little risk.
"The dilution factors here are enormous," Acheson said.
Pets, however, often eat an exclusive diet of the same product -- putting them at greater risk if contamination occurs.
Officials said that as many as three million young chickens out of nine billion slaughtered annually may have eaten feed that could have potentially included an ingredient containing the melamine. They have already been slaughtered for human consumption, but no recall has been issued because there is no evidence that consumption is unsafe.
Acheson said that the investigation tracking contaminated pet food is complex and largescale, and as a result of the broad scope, it could lead to the discovery of new states that are affected.
"There is a distinct possibility that it will broaden," Acheson said. "I'm not saying that it will, but we need to be prepared for that to happen."
Amid U.S. concern about the safety of the nation's food supply, the FDA named Acheson as assistant commissioner for food protection this week.
With files from The Associated Press
