Contrary to what has been claimed in various media over recent years, plastic bottles left in cars will not release harmful dioxins that could possibly cause cancer. But experts still note that heat does react with the plastics of which many bottles are made, a process called leaching — but don’t produce any of the group of toxic chemical compounds called dioxins. Fulton Schools Professor Rolf Halden (pictured in an ASU photograph), director of ASU’s Biodesign Center for Environmental Health Engineering, says there should be little worry of about exposure to cancer-causing chemicals like dioxins from the use of water bottles. Nevertheless, he says, there are chemicals that could cause harm. Halden recommends using chemically inert materials for storage of water and other liquids — for instance, glass instead of plastic.