The Federal Communications Commission should review its cell phone radio-frequency (RF) exposure limit, which was set 15 years ago, because it does not include testing for potential harm from holding phones directly against the body or factor in the latest research, a government report recommended today.

When the RF exposure limit of 1.6 watts per kilogram specific absorption rate (SAR) was established in 1996, phones were bigger, bulkier, and carried in holsters outside of clothes and not in pockets, said Marcia Crosse, director of health care at the U.S. Government Accountability Office (GAO) and co-author of the report. The report adds to mounting concern that the FCC standards are not the best measure of safety.

"The expectation was that people weren't holding it against their head for long periods of time," Crosse told CNET in a phone interview. "They have gotten slimmer, thinner, and more readily able to be put into a pocket. The exposure is different. Even a short distance from the body can dissipate the extent to which you are getting RF or the thermal effect, the heat you get from the phone. We think they need to consider how phones currently are being used and carried around."

The FCC RF energy exposure limit "may not reflect the latest research, and testing requirements may not identify maximum exposure in all possible usage conditions," concludes the GAO report, entitled "Exposure and Testing Requirements for Mobile Phones Should Be Reassessed" (PDF). "By testing mobile phones only when at a distance from the body, the FCC may not be identifying the maximum exposure, since some users may hold a mobile phone directly against the body while in use. Using a mobile phone in this manner could result in RF energy exposure above the maximum body-worn SAR determined during testing, although that may not necessarily be in excess of FCC's limit."

As to the studies of harm from RF exposure, the report says adverse health effects have not been demonstrated conclusively at this point. But this could be because of limitations in the studies, including design flaws.

"The research has been inconclusive," Crosse said. "There have been some studies that give some inkling that at high exposure levels there may be some risk. But studies haven't been replicated or there is the possibility that the study design was biased in some way. So there really is no conclusive evidence."

Among the research mentioned, the Interphone study did not show an increased risk of brain tumors from mobile phone use, "but at the highest level of exposure, findings suggested a possible increased risk of glioma," a type of tumor that starts in the brain or spine, the report said.

Also, cancers can take time to develop, making it difficult to conduct shorter term studies, according to the report. "Epidemiological studies to date have been limited in their ability to provide information about possible effects of long-term RF energy exposure because the prevalence of long-term mobile phone use is still relatively limited and some tumors, including some cancerous tumors, do not develop until many years after exposure," the report said.

The report was hailed by the Environmental Working Group. The "FCC's current standards -- which have never been updated -- allow 20 times more radiation to reach the head than the body as a whole, do not account for the possible risks to children's developing brains and smaller bodies, and consider only the impact of short-term cell phone use, not frequent calling over decades," the group said in a statement . "In 1996, tweens and teens were not consumers of wireless technology, but today it's hard to find a group of young people who aren't armed with the latest mobile device," said Renee Sharp, director of the Environmental Working Group's California office and senior scientist. "Those populations who are now talking and texting daily were not considered by the FCC when it devised its safety standards 15 years ago."

Wireless trade group CTIA-The Wireless Association issued a statement today noting that the FCC has said it is confident that its standards are safe. "The FCC, the FDA, the National Cancer Institute, and the World Health Organization have each evaluated the scientific research on wireless phones that has been conducted worldwide for more than two decades. Each has found that the weight of the scientific research has not established that wireless phone use causes adverse health effects," the statement said. "The FCC has been vigilant in its oversight in this area and has set safety standards to make sure that radio frequency fields from wireless phones remain at what it has determined are safe levels. The FCC's safety standards include a 50-fold safety factor and, as the FCC has noted, are the most conservative in the world."

The FCC announced in June that it would take a closer look at its standards and will seek comments from experts and the public. The agency made that announcement after seeing a draft of the GAO report, according to Crosse. The GAO report was conducted at the request of Representatives Henry Waxman (D-Calif.), Anna Eschoo (D-Calif.) and Edward Markey (D-Mass.).

Yesterday, Rep. Dennis Kucinich (D-Ohio) introduced a bill called The Cell Phone Right to Know Act that would put warning labels on cell phones and require the Environmental Protection Agency to update the RF energy absorption rates.

Meanwhile, the CTIA is suing San Francisco over a law that would require cell phone vendors to provide consumers with a one-page fact sheet about potential health risks of cell phone radiation. The case is slated to begin in the U.S. Ninth Circuit Court of Appeals on Thursday.