Reusable shopping bags have become ubiquitous in conjunction with the growing concern about the environment and excessive waste. These convenient and durable bags can also be used for a variety of other uses, including carrying books or school supplies. However, it turns out that if proper steps are not taken, they can be breeding grounds for germs, including E. coli.

The reason for this is because in addition to the fact that they are used to carry food, which bacteria love, reusable shopping bags are generally not washed. This can lead to the buildup of dirt and bacteria, some of which may pose a health risk to the public.

Researchers randomly tested dozens of the bags used by shoppers in Los Angeles, Tucson, and San Francisco and found that half of them did in fact carry E. coli and other bacteria. In certain instances, the levels in the bags were high enough to raise the risk of serious health problems, and even death, especially young children who can be vulnerable to food-borne illnesses

Furthermore, the scientists found that most consumers did not know of the possible risks involved, and were unaware of the need to regularly wash the bags at least once a week. In fact, upwards of 97% of the users of the bags never washed or bleached them, processes that can kill nearly all of the pathogens that accumulate in the bags.

The information comes at time when disposable plastic grocery bags are increasingly being replaced with the reusable variety. In certain stores, disposable plastic bags are being entirely phased out. In light of this, some health experts believe that a public health education campaign may be in order.

Geographic and climate factors may have influenced the levels of offending bacteria. Places like Los Angeles, where the contamination rates appeared to be higher, may have an ideal climate to induce the bacteria to grow.

Wherever a person lives, the authors recommend that the policy makers as well as the public take precautionary steps to lower the risk of infection. This would include:

• being informed on the importance of cleaning the bags
• separating raw items, especially meat, from other foods
• avoid using the bags to carry books or shoes/clothes
• minimize the time that food is stored in the trunk of your car
• wash any fruits and vegetables that are to be eaten raw

For more information about the study or to obtain a full report, visit the website for Loma Linda University School of Public Health.

This post was included in the latest All Things Eco blog carnival.