The first specific study into the links between the danger of mobile phone use and headaches reported as follows: "Forty respondents from diverse occupations described unpleasant sensations such as a burning feeling or dull ache mainly occurring in the side or back of the head, or near the ear. The symptoms often began minutes after beginning a call, but could come on later in the day. The symptoms usually ceased within an hour after the call, but could last until evening. Symptoms did not occur when using an ordinary (telephone), and were different from ordinary headaches. There were several reports suggestive of effects inside the skull.

75% of cases were associated with digital mobile phones.