A major investigation into whether mobile phones and other wireless technologies affect children's mental development is getting under way.
The study - funded by the government and industry - will track 2,500 11- and 12-year-olds from September. It will look at their cognitive ability - thinking skills, memory and attention - and then repeat the tests in 2017. The researchers say "very little" is known about what impact these technologies have on children.
The World Health Organization has said research in this area is of the "highest priority". More than 160 secondary schools in the outer London area will receive invitations to enrol pupils into the study. Much of the research into mobile phone use has focused on adults and in particular, the risk of brain cancer. No evidence of harm has been established to date.
Nonetheless, NHS advice is that children under the age of 16 should use mobile phones only for essential purposes and, where possible, with hands-free kits.