Consequently, WHO has now categorized radio frequency electromagnetic fields as a "group 2B" possible human carcinogen. Here's how Ed Yong, head of health information at Cancer Research UK, explained it in his detailed analysis of the WHO announcement:  "Group 2B means that there is some evidence for a risk but it's not that convincing. This group ends up being a bit of a catch-all category, and includes everything from carpentry to chloroform."  So it's worth being aware of this classification -- just as you should be mindful of your intake of coffee, another group 2B carcinogen. But this announcement is not a reason to panic.  San Francisco has been wrestling with whether to require cell phones to be labeled for their RF emissions.  Last year, the city tried to mandate cell phone radiation labeling in stores, originally to take effect February 2011. But according to the San Francisco Chronicle, "implementation was delayed until May 1, then June 15. There now is no proposed start date."  The city backtracked on this partly out of concern over a lawsuit filed by the Cellular Telecommunications and Internet Association -- but also because officials didn't know how to ensure the accuracy of the labels.  Scientists aren't sure what's the most realistic, intuitive way to communicate cell phone RF emissions to consumers.  Specific absorption rate, a measure of the rate of RF energy that your body absorbs from the phone, is the most commonly cited benchmark. For a phone to be certified by the FCC and sold in the U.S., for example, its maximum SAR level must be less than 1.6 watts per kilogram.
Following the World Health Organization's announcement that radio frequency emissions from cell phones may increase the risk of some kinds of brain cancer, what do you need to know about the