The GAO report defined some key areas it said would increase understanding of any possible mobile phone RF effects. "For example, additional epidemiological studies, particularly large long-term prospective cohort studies and case-control studies on children could increase knowledge on potential risks of cancer from mobile phone use. Also, studies and experts identified several areas for additional laboratory studies. For example, additional studies on laboratory animals as well as human and animal cells examining the possible toxic or harmful effects of RF energy exposure could increase knowledge on potential biological and health effects of RF energy. Further, additional laboratory studies on human and animal cells to examine non-thermal effects of RF energy could increase knowledge of how, if at all, RF energy interacts with biological systems," the GAO stated.

"Another area identified for additional laboratory research is studies on human volunteers examining the effect of changes in the neurological system, which could help determine if these possible observed changes in neurological functioning from RF energy are adverse effects. In addition to conducting additional research, experts we interviewed reported that the broader body of evidence on RF energy should be re-evaluated when findings from key studies become available, to determine whether additional research in certain areas is still warranted."

The GAO pointed out some ongoing mobile phone radiation studies (and their funding institutions) expected to be complete this year include:

" National Cancer Institute: Examining environmental and genetic factors for meningioma, a type of brain tumor, at research sites in five states.

" National Cancer Institute: Evaluating brain cancer incidence trends in the United States using cancer registry data to determine if trends are consistent with reported epidemiological associations of mobile phone use and certain types of cancer.