Reusable grocery bags, growing in popularity with shoppers going green or complying with local plastic bag laws, could also be growing dangerous bacteria.
Reusable bags tested positive for E. coli, salmonella and coliform bacteria, according to studies by Loma Linda University and the University of Arizona.
The bacteria proliferated wildly when the bag was left in a hot car.
A whole haul of groceries could be infected by contaminated bags, said health educator Rosemary Anthony.
"When you have raw meat or unwashed fruits and vegetables, the germs on the food items themselves can cross-contaminate, can get on the bag," Anthony said.
Regularly washing the bags in a washing machine and then thoroughly drying them is the best way to fight the bacteria. Anthony also recommends placing meat inside plastic bags to prevent leaks.