Pet-food tainting raises food-safety questions

updated 7:15 p.m. ET April 25, 2007

First, cats and dogs were sickened and died after they ate pet food contaminated with an industrial chemical. Then, it was disclosed that hogs were fed the same pet food, raising concerns that the chemical had entered the human food supply.

Some questions and answers about the contamination, the massive recall that followed and the risks to people and animals:

Q: What chemical tainted the food?

A: Traces of melamine, a nitrogen-rich chemical used in a variety of industrial processes, were found in the pet food. Its most common use is to make resins, which in turn can be molded into products like countertops and kitchen utensils, including plastic dinnerware sold as Melmac. It also is both a contaminant and byproduct of several pesticides, including cyromazine, according to the Environmental Protection Agency.

Q: Is melamine toxic to animals?

A: Melamine appears to have caused acute kidney failure in animals that have died or been sickened after eating foods laced with the chemical. Previously, the only known risk was to rodents. When fed to male rats in high doses, melamine indirectly caused tumors by forming stones that irritated the lining of the bladder, according to a 2002 United Nations Environmental Program report. The report concluded its toxicity to mammals is low.

Q: How many pets have died after eating contaminated food?

A: No one knows. Estimates run from a few dozen to several thousand dogs and cats. The FDA has confirmed only about 15 pet deaths.

Q: What about people?

A: The 2002 UN report concluded the potential risk posed by melamine is low. However, the UN based that conclusion on the slim chance that consumers would even come into contact with the chemical.

Q: Has melamine been found in any human foods?

A: No. However, the FDA is beginning to test wheat gluten, rice protein concentrate and at least four other vegetable proteins imported for use by firms that make human food, including pizza dough and infant formula, and those that manufacture animal feed.

Q: What’s the connection to human food?

A: State and federal investigators are looking at hog farms in at least six states that were supplied with salvaged pet food distributed before it was known to be contaminated with melamine. It wasn’t immediately clear which farms had hogs that actually ate the contaminated pet food, though the urine of animals has tested positive for the chemical in California, North Carolina and South Carolina. Some hog farms have been placed under quarantine. A poultry farm in Missouri also may have received some tainted food.

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