"It's not clear what the policy is, and at the very least they owe it to us to explain why they come down this way," said Sandra Eskin, director of the Pew Charitable Trusts' food safety project. "I think many people wonder if this is all because of possible litigation."
Marler said withholding the information can create general fears that damage the reputation of good actors in food production. He said consumers should be allowed to decide for themselves whether to shop and grocery stores or eat at restaurants where tainted produce was sold.
Some states also are slow to interview infected people, he said, which reduces the chances that they remember where they ate.
The Food and Drug Administration said Wednesday that it didn't have enough information to name a possible source of the outbreak. In the past, the agencies have at times declined to ever name a source of an outbreak, referring to "Restaurant A" or using vague terms.
Caroline Smith DeWaal of the Center for Science in the Public Interest says that the decision to withhold a company's name may not only hurt consumers but the food industry, as well. When an item is generally implicated but officials give few specifics, like with the bagged salad, people may stop buying the product altogether.
"I think consumers need more information to make good buying decisions," she said.
Responsibility for disclosing the names of businesses involved general falls to the U.S. Food and Drug Administration because their authority crosses state lines, said Doug Farquhar, a program director with the National Conference of State Legislatures. Farquhar said most states have laws that prohibit the disclosure of businesses that are affected by a foodborne illness.
"In some cases, states go 'rogue' and release the names without FDA approval, in the name of public safety," Farquhar said. "But for the most part, states prefer to let the FDA release the names and take the heat.
Associated Press writers Uriel Garcia in Dallas and Gosia Wozniacka in Fresno, Calif., contributed to this report.
Copyright 2013 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.