BEIJING, May 19 — The largest study to date on whether the mobile devices cause brain tumors ended without a clear answer, according to media reports Wednesday.

The study, conducted by the World Health Organization’s International Agency for Research on Cancer (IARC), surveyed more than 13,000 mobile phone users in 13 countries over the past decade.

The study concluded that radio-frequency energy emitted by cell phones does not increase the risk of two main types of brain tumors, glioma and meningioma.

“The results really don’t allow us to conclude that there is any risk associated with mobile phone use, but… it is also premature to say that there is no risk associated with it,” the IARC’s director Christopher Wild was quoted by Reuters as saying.

The study did find a slightly greater risk of cancer among heavy users.

When researchers looked at the 10 percent of subjects who talked on a cell phone for at least a-half hour a day, seven days a week for ten years, they found a 40 percent increased risk of glioma.

The 21 scientists who conducted the study admitted that this finding suggested problems with the method, or inaccurate information from those who participated.

“We need to look in more depth at that finding in the context of all the other information that’s available to us before we are confident to conclude that there’s no associated risk,” said Christopher Wild. 

On Xinhua Web site: http://news.xinhuanet.com/english2010/health/2010-05/19/c_13303468.htm