Children should restrict their use of cellular phones until more is known about their effects on young brains, according to a British government-sponsored report out today. The BBC reports . RealVideo (download RealPlayer) "The widespread use of mobile phones by children for nonessential calls should be discouraged," the report said. "We also recommend that the mobile phone industry should refrain from promoting the use of mobile phones [to youths under 16]." The study by British medical and science professionals examined existing research on cell phone safety. Sir William Stewart, head of the inquiry, said while there was no evidence so far to suggest a health risk to the whole population, early findings pointed to "subtle effects" on brain function. "We conclude that it is not possible at present to say that exposure to radiation, even at levels below national guidelines, is totally without potential adverse health effects, and that the gaps in knowledge are sufficient to justify a precautionary approach," the report said.

Children at Greater Risk? Stewart, who is a biologist and chairman of the UK's Microbiological Research Authority, said earlier that while he would still use his mobile, he would not let his own grandchildren do so. Children are at risk because they have thinner skulls, smaller heads, and their nervous systems are still developing, making them more vulnerable to adverse effects, he said. The inquiry also called for phone companies to publish the radiation levels of their product when selling mobiles, allowing the public to opt for the safest option. In a consumer update in October, the U.S. Food and Drug Administration said there is "not enough evidence" to conclusively assess the health effects of cell phones. "The available science does not allow us to conclude that mobile phones are absolutely safe, or that they are unsafe," the consumer update said. "However, the available scientific evidence does not demonstrate any adverse health effects associated with the use of mobile phones." The agency still is reviewing the new British report.

The Cellular Telecommunications Industry Association, a cell phone industry group in Washington, believes the sum of research on cell phone use suggests it is safe to use them. "The vast majority of science continues to reaffirm that there are no adverse effects from the use of wireless cell phones," Jo-Anne Basile, vice president of the industry group, said Wednesday, before the report was out. But a scientist who has studied the effect on animal tissue of electromagnetic radiation - a type given off by cell phones - thinks restricting cell phone use by children is "a good idea" because research he's seen indicates there might be risks. Problems in Rats The scientist, Henry Lai of the University of Washington, said that in his tests on rats, cell phone-type radiation appeared to cause learning disabilities, DNA damage to brain cells, and chemical changes in the brain similar to an aspect of Alzheimer's disease. He also pointed to other research that indicates radiation from cell phones may penetrate deeper into children's brains because their heads are smaller. He added that the studies are still incomplete, but he recommends caution for all cell phone users - adults and children. "At this point, we really don't know what kind of health effect a [cell] phone can cause," Lai said. "I would recommend prudent avoidance. Use it as little as possible. But when you have to use it, use it." Basile said biological reactions to radiation such as those found in some of Lai's research do not necessarily reflect a health impact. The British panel's scientists also said a few preliminary studies have suggested radiation may cause subtle biological changes in the brain, but that does not mean health necessarily would be affected.

Yearlong Study The British study was done by a group of medical and science professionals known as the Independent Expert Group on Mobile Phones. The body was formed in March 1999 at the request of the British minister for public health to investigate public safety concerns about cell phones. The group operates under the wing of the British government's National Radiological Protection Board, which has repeatedly claimed there is no evidence of a link between mobile phones and health problems. But the study reportedly sounds notes of caution in several areas. For instance, besides warning against mobile phone use by children, the study recommends more local planning oversight over the placement of mobile phone antennas. The Financial Times reported Wednesday that the report would advise keeping them away from schools, hospitals and residential areas - things citizens groups have been advocating for years. "As a user, you can decide whether or not you have a mobile phone," Phil Willis, a member of Britain's Parliament, told ABCNEWS. "You don't, in fact, decide where the mast is going to be." Guidelines Address Radiation Levels International guidelines governing the amount of radiation cellular phones can emit already include a substantial extra margin of safety to account for the special concerns of children, the elderly and others who might be more vulnerable, said panel member Dr. Michael Repacholi, who heads the World Health Organization's program on electromagnetic fields. The radio waves transmitted by cellular phones mostly come from the antenna. Heat in the handset is not related to radiation, but to the battery depleting with use. Safety is judged partly by something called "specific energy absorption rate," or SAR. It refers to the rate at which the microwaves are absorbed by a piece of tissue in the head of the person using the phone, and is measured in watts per kilogram of tissue.

Most countries use the international guidelines governing the SAR values, which are set at 2 watts per kilogram of tissue. That has a built-in extra margin for those more susceptible to radiation, the World Health Organization says. Not all cellular phones have the same rate, and the value partly depends on the design of the handset. The scientists recommended that the radio wave absorption rate be quoted on the packaging, on the phone itself, in the handset's on-screen menu and on the Internet so consumers can compare the rates. Leaflets explaining the significance of the numbers, as well as the health evidence so far, should be sent to every household in the Britain, they said. Government Reacts The British government said it would act immediately on several of the recommendations, and consider others. "The government will expect SAR measurements to be displayed at all points of sale and with each cellular phone and on the World Wide Web," the Department of Health said in a statement. The department also announced plans to beef up its research program. The cellular phone industry praised the report and said it would contribute to a fund for more research and make information on radiation absorption rates readily available to consumers.