Many people have made the switch from plastic to the more earth-friendly reusable bags, but you may be carrying around more than just groceries.
Scripps' station, KJRH put the reusable shopping bag under the microscope.
"I use them every time I shop for groceries," said Pat Vawter. Vawter is like a growing number of Americans who are making an environmentally-friendly swap.
"I get [reusable grocery bags] all over. I just leave them in the car," Anne Turck said.
Reusable grocery bags are often filled with everything from dairy products to raw meat, so we called researchers at the University of Tulsa to help us put reusable bags to the test.
Most of the shoppers we asked had never thought about how dirty their reusable bag might be.
"I just wad them up and throw them back in my trunk when I'm done using them," Vawter said.
University of Tulsa lab students swabbed the inside of our shoppers bags using two forms of steriles.
"It's just to make sure we're thorough," said Logan Poll, TU bio-chem student.
We even tested a new reusable bag bought at the store that day. The swabs were then rubbed on an agar plate -- which is like food for bacteria -- and taken back to the lab at TU. Each plate was labeled and placed inside an incubator for three days. This allowed any bacteria or fungus present to grow on the agar plate.
Lab students inspected each plate and determined many of them had a form of bacteria, yeast or fungus growing.
Lori Borcher's bag had bacteria and yeast; so did Vawter's. Turcks had bacteria, yeast and fungus.
"Oh gross, that's not good at all," Turcks said.
But Tulsa professor Robert Sheaff said the bacteria, yeast and fungus found on the reusable bags is nothing to cause too much alarm.
"These are generally benign bacteria that help us out in our life with digesting food and making vitamins. So in general, seeing bacteria is not a big problem," Sheaff said.
The brand new bag we purchased at the store also had a little fungus.
However, our lab students assured us this is not too surprising since we bought the bag inside a grocery store, where microorganisms are constantly in the air.
Overall, Sheaff and his students were pleased with the findings.
"We were pretty surprised. We expected to find generally more organisms on the bags and this suggests it's not a very hospitable environment for them to grow. So I would think people could be completely confident in using these bags," said Sheaff.
Still our shoppers said they are going to change some of their habits.
"I'll make sure that food doesn't touch the bag, like actual food. But if it's in a can or box, it's not a big deal," Borcher said.
"I think, for sure, I'll start putting the meat in a plastic bag before I put them in there," Vawter said.
Experts say to think of reusable bags like dirty clothes. Studies show this decreases any possible contamination by about 99 percent.