A smartphone must receive certification from the Federal Communications Commission (FCC) before it can be sold on the US market.
The Specific Absorption Rate (SAR) is one of the criteria that must be met by smartphone manufacturers. SAR is defined as the power absorbed per tissue mass with units of watts per kilogram (W/kg).
The current SAR standard in the US is 1.6 watts per kilogram.
Below are the top 10 smartphones with the highest amount of emitted radiation, according to China Daily.