The warnings may be missed by an awful lot of customers. The United States has 292 million wireless numbers in use, approaching one for every adult and child, according to C.T.I.A.-The Wireless Association, the cellphone industry’s primary trade group. It says that as of June, about a quarter of domestic households were wireless-only.

If health issues arise from ordinary use of this hardware, it would affect not just many customers but also a huge industry. Our voice calls — we chat on our cellphones 2.26 trillion minutes annually, according to the C.T.I.A. — generate $109 billion for the wireless carriers.

The cellphone instructions-cum-warnings were brought to my attention by Devra Davis, an epidemiologist who has worked for the University of Pittsburgh and has published a book about cellphone radiation, “Disconnect.” I had assumed that radiation specialists had long ago established that worries about low-energy radiation were unfounded. Her book, however, surveys the scientific investigations and concludes that the question is not yet settled. Read the rest of this entry »