First the media tell you plastic water bottles are bad for the environment, so they encourage you to drink tap water in reusable containers. Now some of those reusable containers aren’t safe.

NBC’s April 9 “Today” program warned viewers of another threat to society – a miniscule level of bisphenol-A, a chemical found in some water bottles that causes health problems in lab rats when given doses “thousands” of times higher than what exists in the bottles.

“Unfortunately, there’s no level of exposure that's been identified as being safe,” Dr. Leo Trasande, a professor at the Mount Sinai School of Medicine, said in an interview with “Today” co-host Matt Lauer. “And, children and women of child-bearing age are especially susceptible.”

(Article continues below)

Trasande told Lauer bottles with the chemical pose a threat when heated, washed or scratched. But according to the Polycarbonate/BPA Global Group Web site, those are all myths that have been debunked by scientific studies.

“Nevertheless, myths, misinformation and scare stories about polycarbonate bottles continue to circulate, in particular regarding real-life conditions of use that are claimed to result in the release of harmful levels of bisphenol A,” the Web site says. “Several new studies from respected scientists and organizations are now available to clarify whether any of the myths are true and whether the scare stories have merit.”

But that didn’t stop “Today” from warning against many types of water bottles, including the popular Nalgene brand. “[I]n the meantime, you can always check that number on the bottom [the indicator of what type of plastic used is],” reporter Michelle Kosinski said, “or just go back to old-fashioned glass.”