This is the VOA Special English Agriculture Report.   

Melamine is an industrial chemical. So how and why did it get into pet food that caused kidney failure in cats and dogs? And what might be the risk to the human food supply? These are questions that food safety investigators in the United States are trying to answer.

Larry Klimes of Idaho holds a photo of his dog, Joey, who died after eating pet food

Tests found melamine in wheat gluten imported from China and used in pet foods. The United States Food and Drug Administration says Chinese officials said the wheat gluten was not meant for pet food. They said it was meant for industrial use.

But an F.D.A. official noted that melamine can make products appear to contain more protein than they truly do. So one theory is that it may have been added to the wheat gluten on purpose.

In addition, the agency says melamine has been found in some pet food products in rice protein concentrate from China. Those products have been withdrawn from market.

And, in another development, the Royal Canin operation in South Africa has recalled products made in its factory in Johannesburg. The company acted on reports of animals dying after eating food made with corn gluten that contained melamine. Royal Canin USA has announced it will no longer use Chinese suppliers for any of its vegetable proteins.

In the United States, pet foods marketed under more than one hundred different names have been withdrawn, since March.

Melamine has also been identified in the urine of pigs at a California farm. State health officials say the melamine is believed to have come from rice protein concentrate in pet food added to animal feed.

Operations at the farm have been halted while further testing is done. But officials said the evidence so far suggested no serious health risk to anyone who ate meat from the pigs.

The F.D.A. says it is looking for any threat to the human food supply. The agency says it is now testing samples from all shipments of rice protein concentrate from China. The agency says it is also testing all shipments of wheat gluten from China.

The pet food scare as well as recent cases of people getting sick from bad food led a subcommittee in the House of Representatives to call a hearing Tuesday. The lawmakers have questions about the ability of the Food and Drug Administration to protect the safety and security of the nation's food supply.

And that's the VOA Special English Agriculture Report. Transcripts and audio files of our reports are available at voaspecialenglish.com. I'm Bob Doughty.