Whether and if so, how dangerous the radiation from a smartphone actually is when making a call has not yet been conclusively clarified. As a precautionary measure, however, there are limit values that manufacturers must adhere to. Because one thing is certain: mobile communications uses high-frequency electromagnetic fields, some of the energy of which is absorbed by the head when telephoning.
This is called the specific absorption rate (SAR), which is measured in watts per kilogram. The limit for smartphones is 2 watts per kilogram.
No smartphone is critical, so there is no need to worry. However, if you use your smartphone to make a lot of calls and want to be absolutely sure that you are getting as little radiation as possible, you will find 15 tested smartphones from the CHIP best list with the lowest SAR values in the following list.