PHOENIX - Saving the environment could be putting your health at risk.

You know those re-usable grocery bags that are all the rage now?

You might be surprised what's in them.

You get to the grocery store, reusable tote bag in tow, but a new study suggests going green is kind of gross.

Researchers at the University of Arizona randomly tested dozens of reusable grocery bags and say what they found is a serious threat to public health with 51 percent testing positive for coliform bacteria.

Turns out a full 97 percent of those interviewed by researchers have never washed their bags.

So when meat is put in the same bag as other food the bacteria cross contaminates and sticks around long after you've thrown the food in the fridge.

Researchers say throw the bag in the trunk of your car on a hot day and you're basically putting it in an incubator.

But bacteria is everywhere, right? So can using a dirty grocery tote really make you sick?

Dr. Art Mollen says contamination of reusable totes is something to be aware of.

It s the ecoli, it's the salmonella, these are perhaps the most common ones that will affect people causing most often gastroenteritis, and it can become even more serious, Dr. Mollen said.

But don't go back to plastic or paper just yet, the researchers say the solution is simple, keep your bags clean.

The study was sponsored by the American Chemistry Council which does represent businesses in the plastics industry among other things.

The authors of the study say their intent was purely to better inform consumers and lawmakers about risks that could arise from increased use of reusable bags.