We're all aware that plastic is harmful to the environment. One of the ways retailers have ensured that they're cutting down on waste is by charging a fee for plastic bags and encouraging shoppers to use reusable bags instead.

Over the last few years, many people, myself included, have fully switched to using these environment-friendly bags. In fact, I always leave them in the trunk of my car so I won't have an excuse not to use them when I go to the grocery store.

However, an alarming piece of news coming out of an assessment by the University of Arizona and Loma Linda University in regards to these bags will have every reusable bag user on edge.

If you don't wash your bag often, then keep reading because you could be putting your health at risk.

Studies carried out by the researchers at University of Arizona and Loma Linda University found that most people do not wash their shopping bags after use, and they're putting themselves at risk of contracting a food-borne illness.

The results showed that nearly all of the assessed bags harbor large amounts of bacteria, including coliform. About 12 percent of them contained E. Coli.

"These results indicate that reusable bags can play a significant role in the cross contamination of foods if not properly washed on a regular basis," read the study's summary.

The experts also found that bacteria growth increased "10-fold" when bags holding meat were left for two hours in the trunk of a car. So if you have other errands to run, you should leave grocery shopping for last.

What do they suggest as a solution?

Wash your bags as much as you can by machine or hand. The amount of bacteria was reduced by 99.9 percent when the tested bags were cleaned.

It would also help to get into the habit of asking the cashier to bag your groceries separately to reduce the risk of cross-contamination. It's also a good idea to use different reusable bags for every food category.

The FDA and the CDC back up this studies results and have a set of precautions that every shopper should follow:

• Wash reusable grocery bags often.
• Always put raw meats into a disposable plastic bag before putting them in a reusable bag.
• Keep meats, fresh produce, and ready-to-eat foods separated.
• Store reusable bags at home in a cool, dry place, not in the car.
• Do not use reusable grocery bags for other purposes.

The researchers concluded that "the public needs to be educated about the proper care of reusable bags by printed instructions on the bags or through public service announcements."

Do you ever wash your reusable bags?