6,000 hogs linked to tainted feed

WASHINGTON — Federal and state authorities have identified 6,000 hogs in seven states that may have consumed contaminated pet food or pet-food byproducts, the Food and Drug Administration (FDA) said Thursday.

A maximum of about 300 of the animals may have already entered the human food supply, Agriculture Department officials said. The rest of the hogs have been quarantined and are slated to be euthanized.

Officials said they also are looking into the possibility that some chickens may have eaten chow they believe was tainted with chemicals from China.

Officials emphasized that the human health risks of eating pork from animals fed the contaminated food were extremely low. The decision to keep those animals off the market and to reimburse farmers for the losses was made in the interest of extreme prudence, they said.

FDA and Agriculture Department experts also revealed preliminary findings that may explain how low doses of the prime contaminant — the industrial chemical melamine, considered only mildly toxic — may have caused the deaths of some pets. A second contaminant found in the pet food, cyanuric acid, when combined with melamine, appears to prompt the formation of crystals in urine, they said. Those crystals can cause kidney failure.

It is unclear how the two chemicals found their way into pet food, but many experts suspect they were added intentionally so that test results of the protein content of the food would be falsely elevated. Both chemicals are rich in nitrogen, which is the element that the protein tests measure.

FDA officials said the number of pets that the agency has confirmed dead from the contamination remains in the high teens — far fewer than the hundreds claimed by others — but they conceded that they are not making a concerted effort to track that number. Their main concern at this point, they said, is to block the entry of more contaminated ingredients into the country — in part by banning or testing certain imports from China — and to stem the spread of contaminated food products already in the country.

That effort led to the recognition that some pet-food manufacturers that had used tainted ingredients had sold some pet-food waste or scraps to eight hog producers in California, North Carolina, South Carolina, New York, Kansas, Oklahoma and Utah.

There is also a chance that a mill in Missouri bought some of the product and fed it to chickens, they said — a possibility still under investigation.

Having just received the paperwork from China allowing them to get visas, FDA inspectors are preparing to go there to inspect some plants, officials said.