The authors of the study, including several members of Environmental Health Trust, a nonprofit organization devoted to identifying and controlling environmental health risks, pointed to several reasons why. One is that the current assessment method bases evaluations of how much radiation people are exposed to from their phones on measurements taken using a quite large, liquid-filled plastic model of the adult human head (known as the Specific Anthropomorphic Mannequin, or SAM). Smaller people -- 97% of the population, the authors wrote -- will have higher proportional exposure than what is assessed. Children receive twice as much microwave radiation to the head from phones as adults, the study estimated, and 10 times the amount to bone marrow.
Also, current assessments don't examine exposure to parts of the body other than the head, the study noted. Even when a phone is stowed away in a pocket, it continues emitting radiation that could pose a health concern.
The authors reviewed examples of research demonstrating negative effects of cellphone use, including recent epidemiological studies suggesting correlations between cellphone use and brain cancer. (Whether microwave radiation from cellphones can damage DNA and cause cancer is a subject of debate; click here to read a National Cancer Institute fact sheet on the subject.)