Cell Phone Risks Study - Results
All the results combined give a Risk Ratio of 0.9 (0.7 to 1.1 Margin of Error), for the development of acoustic neuroma in cell-phone talkers, compared to people who don't use cell-phones. Taken at face value, this implies that (within the margin of error) there is no evidence that cell-phone use increases the risk for acoustic neuroma. Acoustic neuromas occur roughly at a rate of 1 in 100,000 people, typically between the age of 30 and 60, according to the Acoustic neuroma web site. So the risk for this illness is small to begin with, and cell-phones don't seem to make a significant difference.
However, this is not quite the end of the story... The study also compares the number of tumors that developed on the same side of the head as where the user positions the phone, compared to the opposite side, and again the risk ratio was 0.9 (0.7 - 1.1 Margin of Error). (If cell-phones pose a risk, one expects the number of tumors on the same side as the phone is used to be greater). So far - no evidence of increased risk..
One last analysis was performed that only included cell-phone users who used the phone for 10 or more years total. There the researchers found that the Risk Ratio was 1.8 (1.1 to 3.3 Margin of Error). However, when the users who used cell phones on both sides of their heads were excluded, the Risk Ratio was still 1.8, but the Margin of Error was 1.0 to 3.3. In other words, "no risk" (Risk Ratio of 1.0) is a possible conclusion given the statistics of this study!
The authors of the study point out some possible sources of bias, that could change the results. First, since acoustic neuroma develops slowly, it could impact the the subjects' behavior regarding phone use. Second, not all patients with acoustic neuroma responded to the survey questions, possibly leading to a bias. However, it is not clear that these biases would change the conclusions, if one could adequately assess their impact.