A huge, 30-year study called COSMOS has been launched in Europe to determine whether cell phones cause cancer and other health problems. Meanwhile, policymakers in Sacramento are considering legislation to ensure people know how much radiation their cell phones emit. The wireless industry vigorously opposes such legislation. It argues that its phones comply with regulations, and there is no consensus about risks so people don't need to know this. Our research review published in the Journal of Clinical Oncology found alarming results to the contrary. We reviewed 23 case-control studies that examined tumor risk due to cell phone use. Although as a whole the data varied, among the 10 higher quality studies, we found a harmful association between phone use and tumor risk. The lower quality studies, which failed to meet scientific best practices, were primarily industry funded. The 13 studies that investigated cell phone use for 10 or more years found a significant harmful association with tumor risk, especially for brain tumors, giving us ample reason for concern about long-term use. Nine nations have issued precautionary warnings. It is time for our government to require health warnings and publicize simple steps to reduce the health risks of cell phone use.