Radio frequency radiation from mobile phones can damage DNA in laboratory conditions, European researchers have concluded.

The study, called Reflex (Risk Evaluation of Potential Environmental Hazards from Low Energy Electromagnetic Field Exposure Using Sensitive in vitro Methods), was a four-year, three-million euro research project mainly by the European Union. Results of the project, which ended in May, were published on the Internet earlier this month.

"We have proven that electromagnetic fields - in high and low frequencies - damage cells in individual cell systems," said Franz Adlkofer, executive director of the Munich-based Verum Foundation for Behavior and Environment, which coordinated the project. "But these results can't be readily transferred to human beings. Isolated cell systems are something entirely different from complete organisms."

If, however, similar findings are ever achieved in living organisms such as rats or mice, "then we have a big problem," Adlkofer said. More people own mobile phones today than they do fixed-line phones, with the gap growing larger every year.

After being exposed to electromagnetic fields similar to those produced by mobile phones, the isolated cells showed a significant rise in single and double-strand DNA breaks, according to a summary of the final report. The cells were not always able to repair themselves.

DNA carries genetic information about an organism. It is organized on chromosomes located in the nucleus of a cell.

For their study, researchers used radiation levels between a SAR (Specific Absorption Rate) of 0.3 and 2 W/kg (watts per kilogram), according to the report. Most mobile phones emit radio signals at SAR levels of between 0.5 and 1 W/kg.

SAR is used to measure the rate of radio energy absorbed by body tissue. The SAR limit recommended by the International Commission of Non-Ionizing Radiation Protection is 2 W/kg, according to the group's website.

Adlkofer called for further research, in particular into the impact of electromagnetic fields on mice and rats. Several brain-cancer suits have been filed against US mobile phone companies, but judges have dismissed most of them for lack of scientific evidence.