The vulnerabilities were highlighted last week by Health and Human Services Secretary Tommy Thompson, who said he worries "every single night" about a possible terror attack on the food supply.
The new regulations by the Food and Drug Administration aim to trace the source of food contamination after the fact. Most businesses involved in the nation's human and animal food supply will have to keep records showing where they received food and where they shipped it.
The idea is to help investigators figure out where in a long chain that a particular item may have been tainted. The new set of rules is the fourth in a series of FDA regulations implementing a 2002 bioterrorism law, passed after the 2001 anthrax attacks by nail.