As Jonathan Samet — the dean of the Colorado School of Public Health, who advised the World Health Organization on cellphone radiation and cancer — told me, you can argue anything based on the science we currently have “because there’s not enough evidence to start with.” Actually, there’s not enough high-quality evidence. Before we get into why, and what we know, we need a quick primer on cellphone radiation.

Today, the computer and phone have merged into one device that fits in the palm of your hand. A smartphone is essentially a small computer, yet has many times the computing power of traditional computers. There are no cords to connect you to a base. When turned on in your pocket or being used against your head, the cell phone touches some of the most sensitive parts of the body. Although the cell phone produces lower levels of radiation then past computers, they are now used much closer to the body and for longer periods of time, thus creating more health risks than in the past.
Over time, the number of cell phone calls per day, the length of each call, and the amount of time people use cell phones have increased. Because of changes in cell phone technology and increases in the number of base stations for transmitting wireless signals, the exposure from cell phone use—power output—has changed, mostly lowered, in many regions of the United States (1).