The use of mobile phones over a long period of time can raise the risk for brain tumors , a new Swedish study said on Friday , contradicting (......) the conclusions of other researchers .        The Dutch Health Council , in an overview of research from around the world , last year found no evidence radiation   from mobile phones and TV towers was harmful . A four-year British survey released in January showed no link between regular . long-term use of cell phones and the most common type of tumor .        However , researchers at the Swedish National Institute for Working Life said they looked at the mobile phone use of 905 people between the age of 20 and 80 who had been diagnosed with a malignant brain tumor   and found a link         " A total 80 of these 905 cases were so-called high users of mobile phones , that is they began early to use mobile and or wireless telephones and used them a lot , " the study said .        " The study also shows that the rise in risk is noticeable for tumors on the sided of the head where the phone was said to be used , " it added .        Kjell Mild , who led the study , said the figures meant that heavy users of mobile phones , for instance of who make mobile phone calls for 2 , 000 hours or more in their life , had a 240 percent increased risk for a malignant tumor on the side of the head the phone is used .        " The way to the risk down is to use handsfree , " he told Reuters .        He said his study was the  biggest yet to look at long-term users of the wireless phone has been around inprefix = st1 /Swedenin a portable form since 1984 , longer than in many other countries . If a person always makes calls on his left ear , where might a tumor is produced according to the Swedish survey ?
on the left side of the head on the right side of the head on both sides of the head on the top of the head