The Apple iPhone 7 was set to operate at full power and secured below a tub of clear liquid, specially formulated to simulate human tissue. For 18 minutes, [a probe] repeatedly measured the amount of radiofrequency radiation the liquid was absorbing from the cellphone. This test, which was paid for by the Tribune and conducted according to federal guidelines at an accredited lab, produced a surprising result: Radiofrequency radiation exposure from the iPhone 7 - one of the most popular smartphones ever sold - measured over the legal safety limit and more than double what Apple reported to federal regulators from its own testing. The Federal Communications Commission, which is responsible for regulating phones, states on its website that if a cellphone has been approved for sale, the device will never exceed" the maximum allowable exposure limit. But this phone, in an independent lab inspection, had done exactly that. In all, 11 models from four companies were tested, with varying results. The Tribune asked its lab to conduct a second phase of testing, placing the phones 2 millimeters away from the simulated body. The 2-millimeter distance was chosen to estimate the potential exposure for an owner carrying the phone in a pants or shirt pocket. Under those conditions, most of the models tested yielded results that were over the exposure limit, sometimes far exceeding it. At 2 millimeters, the results from a Samsung Galaxy S8 were more than five times the standard.