The results of a study on brain cancer and cell phone use are already in dispute even though a final draft of the results has yet to be released.

An international group of electromagnetic field activists has taken a critical eye to an Interphone study on handsets and cancer, a 13-country research effort funded in part by the telecommunications industry.

According to groups, including the EMR Policy Institute and the Radiation Research Trust, the Interphone study is systemically flawed and greatly underestimates brain tumor risk.

A report from the activists argues that the study ignored many types of brain tumors; excluded people who had died or were too ill to be interviewed as a consequence of their brain tumors; and excluded children and young adults potentially at higher risk than mature segments of the population.

CTIA reiterated its position on the subject. In a statement, CTIA Vice President of Public Affairs John Walls said that the “peer-reviewed scientific evidence has overwhelmingly indicated that wireless devices do not pose a public health risk.”

“In addition, there is no known mechanism for microwave energy within the limits established by the FCC to cause any adverse health effects.  That is why the leading global health organizations such as the American Cancer Society, National Cancer Institute, World Health Organization and the U.S. Food and Drug Administration all have concurred that wireless devices are not a public health risk. “

His comments are supported by the American Cancer Society, which states on its Web site that “several theoretical considerations suggest that cellular phone towers are unlikely to cause cancer.”

The Society cites the low energy level of radio waves, wavelength and magnitude of exposure to support its stance.

The Interphone study began in 1999 to determine whether cell phone use contributed to brain cancer. According to Interphone researchers, the study has faced systemic problems related to its methodology. The group has yet to publish a final report.

According to Interphone, the study relied on the memory recall of participants to remember handset use. In a 2008 report, Interphone researchers said the errors this caused appeared to be larger for the duration of calls versus the number of calls. Users who rarely used their phones underestimated their use, while heavy users over-estimated their use. The study said that this overestimation “could cause positive bias in estimates of disease risk associated with mobile phone use.”

It is unclear when Interphone’s final results will be released.