A study conducted by the Danish Institute of Cancer Epidemiology in Copenhagen, Denmark, showed that cell phone radiation does not increase the risk of brain tumors. 358,403 Danes over the age of 30 who used cell phones between 1982 and 1995 participated in the study, and another 3.2 million who did not use cell phones served as a control group. A total of 10,729 people were found to have brain tumors during the 1990-2007 follow-up period, 9,883 among those who did not use cell phones and 846 among those who did. The risk of brain tumor development was not statistically different between long-term cell phone users (13 years or more) and non-users, but differed between men and women, with a risk ratio of 1.03 (95% CI: 0.83-1.27) for brain tumor or neurological tumor development among male cell phone users (13 years or more); and 0.91 (95% CI: 0.41-2.04) for women.