Research published Tuesday has found no evidence that mobile phone use causes cancer, but concluded that further long-term studies are required. Workers at five US academic medical centres carried out the work, which tested the hypothesis that there is a link between using a handheld cellular telephone and developing brain cancer. A total of 469 people with brain cancer were questioned, as were 422 people without brain cancer. The study found no significant evidence that those with brain tumours had used a mobile phone for more time than the people in the control sample. However, because some neural tumours have a long induction period, the scientists believe that studies over a longer time-span are needed. This research, which was published in the Journal of the American Medical Association, was carried out between 1994 and 1998. Earlier this month, a team at a Spanish University announced that mobile phones have a greater effect on human brain cells than was previously thought. The scientists, based at Madrid's University Complutense, discovered that a cell's non-spherical shape increases the intensity of the electric field generated within it by a mobile phone. And, writing in The Lancet in December, UK scientist Dr Gerard Hyland warned that children are at the greatest risk from mobile phone radiation -- specifically from low-intensity, pulsed radiation which could affect a number of brain functions. The British government recently launched a £7m research program into the issue of mobile phone safely, but has withdrawn its earlier advice that hands-free mobile phone kits protect against radiation. A report issued by the Consumer Association in October claimed that hands-free kits actually increase the amount of radiation a user is exposed to. Have your say instantly, and see what others have said. Click on the TalkBack button and go to the ZDNet News forum. Let the editors know what you think in the Mailroom. And read what others have said.