After spending 10 years and $24 million to see whether cell phone use leads to brain cancer, the World Health Organization has reached a verdict: it's not quite sure.
In a decade-long survey of nearly 13,000 people across 13 countries, the WHO's International Agency for Research on Cancer (IARC) determined that most cell phone use did not lead to an increased risk of either meningioma, a common but typically benign form of cancer, or glioma, a rare but more dangerous type of brain cancer.
The study results, released Monday, did see "suggestions" that using cell phones for long periods of time on the same side of the head could lead to an increased risk of glioma, especially around the temporal lobe. However, the authors acknowledged that possible biases and errors from those participating in the survey meant that these results were not conclusive enough to directly blame cell phone radiation for such tumors. For example, people were asked to try to keep track of how often they used their cell phones and on which side of the head over a period of 10 years.
To conduct the study, 21 scientists from around the world came together in 2000 to form the Interphone International Study Group under the auspices of the IARC. Among the many people interviewed were those who had brain tumors--2,708 individuals with glioma and 2,409 with meningioma--so the researchers could gauge their cell phone activity to see if there was a direct correlation with their cancers.
With a definitive answer still lacking, the IARC concludes that further study is needed, especially since cell phone use has increased dramatically since 2000, particularly among younger people.
"An increased risk of brain cancer is not established from the data from Interphone," Dr. Christopher Wild, IARC's director, said in a statement. "However, observations at the highest level of cumulative call time and the changing patterns of mobile phone use since the period studied by Interphone, particularly in young people, mean that further investigation of mobile phone use and brain cancer risk is merited."
The researchers also want to conduct a new study to determine whether cell phone use leads to an increase risk of tumors in the ear's acoustic or auditory nerve and the parotid gland, one of the glands that produces saliva.
Almost 25 percent of the $24 million needed to fund the study was contributed by the cell phone industry, but WHO said it took precautions to ensure that the researchers were able to work independently.
Encouraged by the lack of evidence pointing to any clear risk in cell phone use, two key mobile-phone industry groups weighed in with statements on the study.
"The overall conclusion of no increased risk is in accordance with the large body of existing research and many expert reviews that consistently conclude that there is no established health risk from radio signals that comply with international safety recommendations," Dr. Jack Rowley, director of research at the GSM Association, said in a statement. "The results reported today underscore the importance of utilizing complete and thorough data analysis before reaching conclusions."
John Walls, the CTIA vice president of public affairs, said: "All cell phones sold in the U.S. must comply with the FCC's radio frequency exposure standards, which are designed to include a substantial margin of safety for consumers. Numerous experts and government health and safety organizations around the world have reviewed the existing database of studies and ongoing research and concluded that RF products meeting established safety guidelines pose no known health risk."
The full study results have been published in the International Journal of Epidemiology.