Courts and regulators generally consider epidemiologic studies such as these to be the gold standard for measuring human health risks. But they still drew criticism from some researchers. A major limitation in all of them, the authors admit, is that most of the subjects had been using their phones only for 1 to 3 years, whereas cancer takes 10 to 15 years to develop. Swedish epidemiologist Kjell Hansson Mild explains that in order to detect a modest increased cancer risk from cell phone use, “we need a long latency period and large numbers of people. A 10-year latency is what you should aim for.”