But this study also has some drawbacks. First, it is based only on whether or not people had a cell phone subscription at the time. It didn’t measure how often these people used their phones (if at all), or if people who didn’t have a subscription used someone else’s phone. There are also limits as to how well this study might apply to people using cell phones today. For example, while the cell phones used at the time of the study tended to require more power than modern cell phones, people also probably used the phones quite a bit less than people use their phones today.

For now, it’s probably better not to spend too much of your time worrying: you’re surrounded by cellphone signals, Wi-Fi signals, and all other kinds of radio frequency radiation day in and out — not just when you put your phone up to your face. And until the evidence suggests otherwise, all of this is still considered less of a cancer risk than eating red meat (which you shouldn't freak out about that much either).
“The near field plume is the one we’re most concerned with. This plume that’s generated within five or six inches of the center of a cell phone’s antenna is determined by the amount of power necessary to carry the signal to the base station,” he explains. “The more power there is, the farther the plume radiates the dangerous information-carrying radio waves.”

But according to the FCC, comparing SAR values between phones can be misleading. The listed SAR value is based only on the phone operating at its highest power, not on what users would typically be exposed to with normal phone use. The actual SAR value during use varies based on a number of factors, so it’s possible that a phone with a lower listed SAR value might actually expose a person to more RF energy than one with a higher listed SAR value in some cases.

The frequency of radiofrequency electromagnetic radiation ranges from 30 kilohertz (30 kHz, or 30,000 Hz) to 300 gigahertz (300 GHz, or 300 billion Hz). Electromagnetic fields in the radiofrequency range are used for telecommunications applications, including cell phones, televisions, and radio transmissions. The human body absorbs energy from devices that emit radiofrequency electromagnetic radiation. The dose of the absorbed energy is estimated using a measure called the specific absorption rate (SAR), which is expressed in watts per kilogram of body weight.