When the Centers for Disease Control and Prevention published new guidelines 18 months ago regarding the radiation risk from cellphones, it used unusually bold language on the topic for the American health agency: "We recommend caution in cellphone use."
The agency's website previously had said that any risks "likely are comparable to other lifestyle choices we make every day."
Within weeks, though, the C.D.C. reversed course. It no longer recommended caution, and deleted a passage specifically addressing potential risks for children.
Mainstream scientific consensus holds that there is little to no evidence that cellphone signals raise the risk of brain cancer or other health problems; rather, behaviors like texting while driving are seen as the real health concerns. Nevertheless, more than 500 pages of internal records obtained by The New York Times, along with interviews with former agency officials, reveal a debate and some disagreement among scientists and health agencies about what guidance to give as the use of mobile devices skyrockets.
Although the initial C.D.C. changes, which were released in June 2014, had been three years in the making, officials quickly realized they had taken a step they were not prepared for. Health officials and advocates began asking if the new language represented a policy change. One state official raised the question of potential liabilities for allowing cellphones in schools.