SEATTLE - There's new developments in the on-going story of contaminated pet food. Federal health officials confirm that the ingredient believed to be killing cats and dogs, has also entered the human food supply.
When this story broke back in mid-March, it was assumed the contamination was limited to pet food. But now it's clear that various livestock in the U.S. have been given animal feed containing the chemical melamine -- a chemical that is not supposed to be in pet or people food.
Last week we learned contaminated animal feed was fed to hogs. Just Monday, there was confirmation that tainted feed was fed to chickens.
The FDA says 38 poultry farms in Indiana received contaminated feed from China in early February. Of those, 30 of the farms raise broiler chickens for humane consumption.
All of the broilers that may have eaten feed contaminated with melamine have since been processed into food. The FDA says the likelihood anyone would get sick after eating this chicken is "very low."
When melamine first showed up in tainted pet food, it appeared this was an isolated incident. But Chinese business executives tell the New York Times that melamine has been "routinely added" to various types of animal feed in China for years.
Why? To make buyers think that the protein levels are higher than they actually are, boosting the price.
So why did melamine suddenly start killing pets in the United States? Scientists now say because it was combined with another chemical.
"I think we've identified what we feel is an important and likely underlying positive agent of why the animals are getting sick," said Alan Wilderman with the University of Guelph.
Scientists from Canada and the U.S. believe they may have unlocked the mystery. They've learned that melamine combined with another contaminant found in the pet food--- cyuranic acid-- forms crystals in the kidneys.
"What we've done is experiments that show if you take cat urine and you add melamine to it and cyanuric acid, the crystals will form in the cat urine in a test tube as we're watching them, so it happens within a matter of hours," Wilderman said.
The crystals are suspected of killing the pets, and the ASPCA has just seen a case that suggests that's exactly what happened.
"We had one case recently where the cats' kidneys were completely obstructed and when we went to surgery to relieve the obstruction, there was no normal stone, instead the uridors were completely full of these melamine type crystals," said Dr. Louise Murray, with the ASPCA Animal Hospital.
And now the pet food investigation has turned into scrutiny of the human food supply.
"We see the pet food recall as a warning sign for the government that they need to do more to protect the food supply," said Caroline Smith DeWaal with the Center for Science in the Public Interest. "It could easily happen to an ingredient used in human food as well."
The FDA has already announced 6,000 hogs in several states that may have eaten tainted feed should be destroyed, and not put into the human food chain.
Meanwhile, the FDA's investigation into China continues. A lawyer for one of the U.S. companies that received tainted wheat gluten from China confirms to CNN that his client received a search warrant last week for documents and computer files. FDA inspectors are expected to head to China to continue the probe.
Once again, the FDA says there is no evidence the animals fed the contaminated feed are harmful to humans, which is why the FDA has not issued any recalls for hogs or chickens in question.
