Study warns that reusable bottles can be a health risk: In what sense?

In recent years, reusable bottles have become a symbol of environmental awareness. We take them to the gym, to work, and even travel with us. But what happens when that eco-friendly gesture becomes an invisible haven for bacteria? Reusable bottles can accumulate more bacteria per square centimeter than a container of pet food. According to a study by the University of South Florida, reusable water bottles—especially plastic ones with narrow nozz…