A study by environmental-health professors at the University of Arizona and Loma Linda University in California says that reusable bags from grocery shops contain high levels of disease-causing bacteria.
"We're so used to disposable bags that we don't think to wash reusable ones," said co-author of the study Ryan Sinclair, a researcher at Loma Linda. "If you leave bags in the trunk ... the temperature increase will help the bacteria grow more efficiently."
The study found that 12% of the reusable bags contained E. coli a dangerous bacteria that can sometimes cause fatal infections.
The study recommends that people should wash their reusable bags after each use and then bleach them. Furthermore they should not carry meat, gym clothes or books in these bags.