Finland's radiation watchdog is to study the effects of mobile phones on human proteins by direct tests on people's skin, to see if handset transmissions affect their health. A pilot study, to be conducted next week, will expose a small area of skin on volunteers' arms to cellphone radiation for the duration of a long phone call, or for one hour, research professor Dariusz Leszczynski said on Friday.

Researchers will then take a skin sample to study and compare with one taken before the radiation exposure, he told Reuters.

Cell samples used in previous laboratory tests by the Radiation and Nuclear Safety Authority were all from women, and to keep consistency in the data, 10 female volunteers will be used in the new study -- all of them employees at the watchdog.

In previous tests, Leszczynski's group found evidence of mobile phone radiation causing cell-level changes such as shrinkage, but he said it was still impossible to say if that had significant health effects.

"Cells function in a different way when they are in the body than in laboratory surroundings. Now we want to confirm whether radiation causes cell level changes in humans as well," he said.

The results of the study are due by the end of the year, and Leszczynski's team hopes to show if radiation has any impact on the body's natural barrier that prevents toxins and other dangerous proteins that might be in the bloodstream from reaching brain cells.

Some researchers suspect brain cancer has become more common as a result of cellphone use, but there is no clear evidence to support that, Leszczynski said.

"If harmful proteins get through to the brain, it could have an indirect link with cancer, but this is pure speculation," he added.

Finland, home to top global mobile maker Nokia, has one of the most mature telecom markets in the world, with almost everyone having a mobile handset.