An international study that is the largest yet to focus on cell-phone use and certain types of brain cancer didn't find a conclusive link, researchers said.
The study of more than 10,000 people found that most use didn't raise the risk of developing two types of tumors, according to results in the International Journal of Epidemiology. There was a "suggestion" that cell phones may be tied to gliomas, a form of brain malignancy, among the heaviest users, the authors said. That data, though, was flawed, they concluded, saying that more study would be needed to establish a definitive link.
The report by the World Health Organization's International Agency for Research on Cancer is the latest in a series of conflicting studies exploring whether a connection exists between cellular phones and cancer. Most have failed to identify a link. The debate has turned on the fact that the phones emit radio waves that have been found, at higher levels, to heat body tissue and spur tumors, according to the National Cancer Institute's website.
"An increased risk of brain cancer is not established," said Christopher Wild, director of the International Agency for Research on Cancer, in a statement. He called for more study, citing the researchers' "observations at the highest level of cumulative call time and the changing patterns of mobile phone use since the period studied - particularly in young people."
More than one-third, or $6.8 million, of the study's $23.7 million cost came from the cell-phone and other industry sources, according to a news release from the World Health Organization. The researchers came from 13 countries, including Australia, Canada, Denmark, Finland, France, Germany, Israel, Italy, Japan, New Zealand, Norway, Sweden and the U.K. No one was involved from the U.S.
The number of wireless accounts grew to 285.6 million in December from 109.5 million in 2000, according to CTIA.
Earlier studies include a December report by investigators from the U.S. National Cancer Institute using registries from Denmark, Finland, Norway and Sweden, covering more than 16 million adults, to track the number of people diagnosed with brain tumors since 1974, when cell use in those countries began seeing widespread use. The researchers found no surge in cancer cases.
A study of 420,000 Danish people who used cell phones for an average of 8.5 years, reported in December 2006, also found no increase in cancers.