A group of international scientists today released a report that again raises concerns about the possibility of a connection between cell phone use and brain tumors, noting that a recent Swedish study saw a 400% increase in risk for teenage cell phone users.

The 37-page report, from a group called the International EMF [Electromagnetic Field] Collaborative, summarized what it said are the dangers of cell phone use, especially for children, and attempted to counter the upcoming Interphone study, which is supported by the wireless industry in 13 countries, mainly in western Europe.

"Some countries are already banning cell phones over health concerns, with France saying children in elementary schools can only use them for texting," said the report's author, Lloyd Morgan, in an interview.

"Cell phones can be used appropriately and have a certain usefulness, but I fear we will see a tsunami of brain tumors, although it is too early to see that now, since the tumors have a 30-year latency," he added. "I pray I'm wrong, but brace yourself."

However, John Walls, vice president of public affairs for the CTIA, a group representing wireless carriers and handset makers in the U.S., issued a statement today saying "peer-reviewed scientific evidence has overwhelmingly indicated that wireless devices do not pose a public health risk." He noted that the American Cancer Society, the National Cancer Institute, the World Health Organization and the U.S. Food and Drug Administration have all concurred that wireless devices are not a public health risk.

Morgan, a retired electronics engineer based in Berkeley, Calif., and a member of the Bioelectromagnetics Society, wrote the report, "Cellphones and Brain Tumors: 15 Reasons for Concern," with the endorsement of 43 scientists and experts from the U.S., Australia, Brazil, Canada, Finland, France, Germany, Greece, Ireland, Russia, Spain, Sweden and the U.K. Groups endorsing the findings include the EMR Policy Institute, the Peoples Initiative Foundation, ElectromagneticHealth.org, The Radiation Research Trust and Powerwatch. A copy of the report and a short video are available at RadiationReserarch.org.

Morgan said the most compelling research linking cell phone usage to brain tumors was noted in a study published in May 2009 in the International Journal of Oncology by a Swedish team of scientists led by professor Lennart Hardell. It noted that use of digital cell phones and cordless phones by people who started using such devices when they were teenagers or younger led to a 420% increase in the risk of brain cancer. Hardell had earlier found that use of analog cell phones caused a 700% increase in the risk of cancer; today's digital phones have lower power requirements and don't represent as much of a threat as analog phones.

The cancer risk comes from holding a cell phone close to the head over longer periods of time, the International EMF Collaborative study notes. It recommends eight steps for reducing exposure to cell phone radiation for adults and children. The steps include using wired headsets rather than wireless headsets and sending text messages instead of talking on the phone. Also, the study recommends avoiding the use of cell phones in moving vehicles, since the devices require more power and radiation as they move farther away from cell towers. And it suggests that people avoid using cell phones inside of buildings, because phones need less power and radiation outdoors.

The study also recommends keeping cell phones away from your body, including in pockets, and it suggests using cell phones like answering machines -- keeping them off until you're ready to return calls. It also urged people to use corded, land line phones whenever possible. Moreover, it recommended that children not be allowed to sleep with cell phones under their pillows, and it cautioned parents not to allow children under 18 to use cell phones except in emergencies.

The International EMF Collaborative's study details 11 flaws in the upcoming Interphone study, which is due to be released this fall by major carriers in 13 countries, not including the U.S. Based on components of the Interphone report that have already been published, the International EMF Collaborative says that study has a number of flaws. Among other things, it excluded people who use portable phones, even though those devices also emit microwave radiation, just as cell phones do. The Collaborative said the Interphone study also excluded many types of brain tumors and eliminated subjects who died or were too ill be interviewed. Moreover, the Interphone study did not include children and young adults, who are more vulnerable, according to the International EMF Collaborative.