FDA to test human food supply for melamine

NEW YORK (CNN) -- The Food and Drug Administration says it will, for the first time, test ingredients imported for use in the human food supply in connection with the nationwide pet food recall that has killed, by some estimates, thousands of pets.

In addition, the FDA announced plans Tuesday to expand testing of the animal food supply after hogs on farms in three states were quarantined after testing positive for the substance at the center of the recall, the toxic agent melamine.

A poultry farm in Missouri is also being investigated, federal officials said.

Wheat gluten, corn gluten, corn meal, rice bran and rice protein are among the imported products being tested in both the animal and human food supply.

"I want to emphasize that this is a proactive step, " said David Acheson, chief medical officer for the FDA's Center of Food Safety and Applied Nutrition.

The comprehensive testing will begin at the end of the week and focus on public awareness and checking of samples, according to Acheson.

The FDA said hog farms in California, North Carolina and South Carolina have been quarantined after tests found melamine in the swine's urine. Owners of a hog farm in Ohio are also working with the FDA.

Hogs from farms in New York and Utah have also been placed on hold for distribution but testing has yet to confirm the presence of melamine in those animals, federal officials said.

The FDA has officially tallied 16 animal deaths related to the wheat gluten-pet food recall, but other organizations have put the death toll in the thousands.

More than 100 brands of pet food from Menu Foods (Charts), Hill's Pet Nutrition, P&G (Charts, Fortune 500) Pet Care, Nestle Purina (Charts) PetCare, Del Monte (Charts) Pet Products, and Sunshine Mills have been recalled in cooperation with the FDA.

--CNN's Katy Byron contributed to this report