In a study that may shed some light on whether cellphone use is harmful to callers, Swedish scientists found that radiation emitted by the world’s most common mobile phones burns holes in the brains of rats. reports that Swedish neurosurgeon Leif Salford and his team tested the radiation emitted from Global System for Mobile communications phones on 12- to 26-week-old rats. According to the researchers, the age group of the animals tested is equivalent to that of human teenagers — who tend to lead the pack in cell-phone use worldwide. GSM phones are reportedly the most commonly used around the globe, particularly in Europe, Asia and the Middle East.