*Diedtra Henderson of the Boston Globe reports that up to 6,000 hogs in California, Kansas, New York, North Carolina, Oklahoma, South Carolina, and Utah that ate pet food tainted with industrial chemicals cannot be safely sold to humans, federal authorities said yesterday, and should be euthanized at the farms where they have been held from the market. Several hundred of the swine have already entered the human food supply. 

Federal officials said they were taking the step out of an "abundance of caution," since the concentrations of contaminants in the hogs was likely too low to harm humans. There is nothing in the scientific literature, however, about the effect on humans of consuming melamine and cyanuric acid — chemicals used to produce plastics and pool cleaners that were illegally added to food ingredients exported from China.