Cellphone Makers Already Warn About Radiation Exposure

June 3, 2011— -- The World Health Organization's conclusion this week that low-level radiation from cellphones possibly causes cancer should have come as no surprise to anyone who reads the user manual. Placing cellphones in the same category as lead and engine exhaust, the director of the WHO's cancer research arm said in a statement: "Given the potential consequences for public health … it is important to take pragmatic measures to reduce exposure."

But virtually every major cellphone maker already recommends that users take precautions. Somewhere in their user manuals are instructions for customers to keep their phones away from their bodies to avoid exceeding Federal Communications Commission exposure limits.

Researchers at Washington, D.C.-based, nonprofit Environmental Working Group examined more than a dozen of the most popular models. Below are the results, which were based on tests that assumed callers were using a belt holster. The government has yet to test for phones carried in jacket or pants pockets, the way most users carry them. It's one of many questions the science has yet to answer definitively.

ABC News' Michael Murray contributed to this article.