The U.S. Food and Drug Administration has begun a year-long nationwide effort to test pet food for salmonella contamination, but the key concern is not the health of dogs and cats — it’s of their owners.

FDA investigators began in October taking samples of dry pet food, pet treats and diet supplements from distributors, wholesalers and retailers like PetSmart, PetCo, WalMart, Costco, Sam’s Club and Target.

People turning to dog food for nourishment is "an urban legend," said Duane Ekedahl, president of the Pet Food Institute, but the FDA said in a memorandum released this week that it is "particularly concerned about salmonella being transmitted to humans through pet foods, pet treats and supplements for pets that are intended to be fed to animals in homes, where they are likely to be directly handled or ingested by humans."

The agency pointed to CDC data that show 70 people got sick from January 2006 through December 2007 in connection with salmonella-tainted dry dog food produced in Pennsylvania.

About $8 billion worth of dry dog food, $2 billion worth of dog treats, $3.7 billion worth of dry cat food and $427 million worth of cat treats were sold in the U.S. last year, according to Euromonitor International, a market research company.

From the achieves: Doug Powell and Randy Phebus talk about salmonella in pet food in 2008.