Loma Linda Researchers Helped Expose Dirty Little Bags

What do you do to stay healthy? Get a flu shot? Exercise regularly? Wash your reusable bags?

Believe it or not, washing those should probably be on your list, say the creators of a study appropriately titled Assessment of the Potential for Cross Contamination of Food Product by Reusable Shopping Bags.

According to the study, reusable bags are seldom, if ever, washed. And, as a result, large numbers of bacteria were found in several bags tested by researchers with Loma Linda University and the University of Arizona. And those bacteria could transfer to whatever food you put in the bags.

“The results were not surprising to me,” said Dr. Ryan Sinclair, PhD. an assistant professor of environmental and occupational health with the Loma Linda University School of Public Health. “It’s not surprising when you look at something that holds food.”

The report was originally released in the summer of 2010 and created discussion.

A total of 84 bags, 25 from the Los Angeles area, 25 from around San Francisco and 34 from Tucson, were examined. For the bags collected locally, Sinclair says he stood outside of stores and the Redlands Farmer’s market.

“We offered them a new bag to replace the old one,” Sinclair said. “And most people said sure.”

Each one was tested and researchers found coli form bacteria in half the samples. Escherichia coli was found in 12 percent of the bags along with a wide range of enteric bacteria, including several opportunistic pathogens, according to the report.

The bags' owners were asked if they had washed the bags and “95 percent said no,” Sinclair said.

But before you go running back to plastic bags, Sinclair said the problem is easily resolved with hot water and some bleach-based detergent.

Sinclair washed the bags and said they came out fine. “A PhD student also washed them in a hand bucket. He found it was a really good way to kill off bacteria,” Sinclair said. “I don’t know who would want to do that much work.”

Bleach based anti-bacterial spray may also be used, he said. But don’t be shy about cleaning the bags, Sinclair said.

“If something happens to them, it costs you, what, $1?” Sinclair said. “I also like reusable bags. So don’t be discouraged.”

Sinclair, who worked with Doctors Charles Gerba and David Williams with the Department of Soil, Water and Environmental Science at the University of Arizona in Tucson is now preparing to submit the report for peer review and publication in a medical journal.