Good news if you’re that grocery shopper that always forgets your reusable bags at home or in the car: Now you have a back-up story to scare the clerk. A study funded by the American Chemistry Council examined reusable grocery bags to find a big chunk of them riddled with bacteria. Coliform bacteria was found in about half, while E.coli was found in 12 percent of the bags. Both strains can commonly be found in the feces of warm-blooded animals.

The study found that washing the bags by hand or with running water reduced bacterial levels to almost nothing.

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The study was a response to a California bill picking up speed that would ban single-use plastic bags statewide. The ban is already active in San Francisco and has the support of California Govenor Arnold Schwarzenegger. The proposed bill would force shoppers to bring their own totes to grocery stores or purchase paper bags made of at least 40 percent recycled material. The group conducting the study, which represents plastic bag manufacturers, is understandably against the ban.

E. coli organisms can survive several weeks on counter tops and other surfaces and up to a year in some materials, like compost. Symptoms of infection include stomach cramps or tenderness, bloody diarrhea, nausea and vomiting. Only small amounts of the bacteria are needed for a target to be infected.

The Centers for Disease Control and Prevention estimates at least 2000 Americans are hospitalized and about 60 die every year as a direct result of E. coli infection and complications.