To many people, the notion that cellphones or cell towers might present a health risk long ago receded into a realm somewhere between trivial concern and conspiracy theory. For decades, the wireless industry has dismissed such ideas as fearmongering, and federal regulators have maintained that cellphones pose no danger. But a growing body of scientific research is raising questions, with the stakes heightened by the ongoing deployment of hundreds of thousands of new transmitters in neighborhoods across America. ProPublica recently examined the issue in detail, finding that the chief government regulator, the Federal Communications Commission, relies on an exposure standard from 1996, when the Motorola StarTAC flip phone was cutting edge, and that the agency brushed aside a lengthy study by a different arm of the federal government that found that cellphone radiation caused rare cancers and DNA damage in lab animals. The newest generation of cellphone technology, known as 5G, remains largely untested.