A chemical tied to pets suffering kidney failure is commonly added to feed in China, while Canadian researchers say they've pinpointed exactly why it can be harmful.
Wang Jianhui, manager of the Kaiyuan Protein Feed company in China's northern city of Shijiazhuang, downplayed the toxic effects of melamine.
"We've been running the melamine feed business for about 15 years and receiving positive responses from our customers," he told The Associated Press by phone.
"Using the proper quantity of melamine will not harm the animals. Our products are very safe, for sure."
AP reports the practice of using melamine may be widespread in China, but the chemical is banned in North America.
In March, more than 100 brands of pet food that contained melamine-tainted wheat gluten were recalled across Canada and the U.S. Ontario-based Menu Foods recalled 60 million cans of wet pet food.
When melamine is added to feed, it makes the food appear as if it contains a higher amount of protein, although the nutritional value stays the same.
An unknown number of cats and other pets have suffered kidney failure because of food tainted with the chemical.
Researchers at the University of Guelph in Ontario said melamine can have a dangerous effect when mixed with cyanuric acid, the other contaminant found in the imported wheat gluten.
The two chemicals react to form crystals that can block kidney function in animals. Researchers at Guelph said they were able to reproduce the same effect at the university's Animal Health Laboratory.
"When we did it in the laboratory ... it was instantaneous," John Melichercik, Director of Analytical Services for Laboratory Services told CTV.ca.
"What were two clear liquids, when were combined, actually go very murky and if you leave it for a little bit, these crystals settle out and you can pick them off and then analyze them."
China's government has said it will allow U.S. officials from the Food and Drug Administration to investigate melamine contamination.
There is no evidence that melamine is harmful to humans, although there is also no research on possible health effects when melamine is combined with other substances.
Ji Denghui, manager of China's Sanming Dinghui Chemical Trading Co., said he believes melamine is safe when used sparingly.
"As to whether melamine is toxic or not, I believe it won't do any harm if there is only very small amount," Ji told AP. "Otherwise, those companies could not do that."
With files from The Associated Press
