SciAm on the Pet Poisons: chemistry at last

SciAm has a reasonable update, with a bit of science. The headline is misleading; the companies using melanine did not expect it to injure animals -- they didn't really want to get caught.

Were Our Pets Deliberately Poisoned?: Scientific American

..."We have found cyanuric acid, which is somewhat related to melamine," says Stephen Sundlof, director of the FDA's Center for Veterinary Medicine. Both compounds have high levels of nitrogen, which are a measure of protein in a food product. Wheat, rice and corn glutens are forms of vegetable protein that are used as binders in soft (or wet) pet food. They can also be added to dry food to enhance the protein content, says Dave Griffin, owner of the independent pet store Westwood Pet Center in Bethesda, Md. Griffin, who has worked in the pet industry for 35 years, adds that because of lax labeling requirements, pet food manufacturers are not required to specify the source of protein—that is whether it is from meat or meal.

Brent Hoff, a clinical toxicologist and pathologist at the University of Guelph in Ontario, confirmed the presence of cyanuric acid in both the rice protein concentrate as well as in crystals found in the urine and kidneys of sick animals. Late last month, those crystals, which are brown and round in shape, were found to be made up of 30 percent melamine; the composition of the other 70 percent has yet to be determined, although it is known to contain cyanuric acid as well as amilorine and amiloride, which are by-products of melamine.

Cyanuric acid may have been added separately to the feed, however it's also likely it was present because it can result from the bacterial degradation of melamine, says Richard Goldstein, a kidney specialist at the Cornell University College of Veterinary Medicine. Much like melamine, cyanuric acid, which is typically used in chlorination during pool cleaning, is not known to have a high toxicity. "People swallow it all the time" in pool water, Goldstein says. However, he adds, "It does have a toxic effect on the kidneys in very high doses…. Combining it with melamine may cause it to crystallize and hang out in the kidneys a lot longer than normal."

Hoff and his colleagues at Guelph are continuing to analyze the crystals found in sick pets to determine "how close the crystals are to the precipitate [the solid that results when two chemicals react] of melamine and cyanuric acid." For now, though, Hoff cautions, "We haven't got it down pat."

The FDA also announced that it is taking preemptive steps to try to prevent further damage by testing protein ingredients for melamine in a variety of pet and human food, which contains protein additives—like wheat gluten and rice protein concentrate—that are imported from outside the U.S. David Acheson, chief medical officer for the agency's Center for Food Safety and Applied Nutrition, says the new measures are to determine "where else may this be" in order to keep the contaminant from sickening any more pets and, perhaps, people as well....

..."As part of this approach," Acheson says, the "FDA and the state authorities are going to raise awareness with manufacturers and processors about the importance of knowing all there is to know about their suppliers." Thus far, contaminated wheat gluten and rice protein concentrate has been discovered in North America, and melamine-containing corn gluten was also used in pet food in South Africa. All of the tainted protein additives have been sourced to Chinese manufacturers...

... The FDA will finally get a shot at getting to the root of the matter now that Chinese officials have relented to requests to allow inspectors into the country to probe gluten suppliers implicated in the potential scandal. The FDA reported that it had finally received letters of invitation from the Chinese government, which are necessary to obtain visas. The agency plans to investigate the manufacturing practices of the two suppliers of the melamine-containing rice and wheat glutens that have been imported by the U.S., to determine if and how cross-contamination may have occurred.

... The Center for Science in the Public Interest, a Washington, D.C.-based group that advocates health and food safety, recommended that the FDA bar the import of grains from China....

So far the FDA hasn't made any significant changes. I don't know if they can without congressional action.