One person has died, and dozens of others were sickened, in the 10-state E. coli outbreak, linked by Food and Drug Administration officials to bagged spinach. The FDA has warned people not to eat bagged spinach and said washing it wouldn’t solve the problem because the bacteria is too tightly attached.

"If you wash it, it is not going to get rid of it," said Robert Brackett, director of the FDA’s Center for Food Safety and Nutrition.

The warning applied to consumers nationwide because of uncertainty over the origin of the tainted spinach and how widely it was distributed. Health officials did not know of any link to a specific growing region, grower, brand or supplier.

Officials believe the spinach may have been grown in California, and federal and state health officials were there trying to pinpoint the source of the contamination. Most of the spinach crop at this time of the year comes from California. A special effort is under way in the Salinas Valley of California, a major leafy-vegetable growing region.