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The researchers studied 12- to 26-week-old rats because their developmental age is comparable to that of human teenagers, who are some of the heaviest users of mobile phones. "The situation of the growing brain might deserve special concern," the study authors wrote, "since biological and maturational processes are particularly vulnerable. We cannot exclude that after some decades of often daily use, a whole generation of users may suffer negative effects as early as middle age."

Three groups of rats were exposed for 2 hours to GSM mobile phone EMFs of different strengths. GSM, which stands for Global System for Mobile Communications, is the main standard for mobile phones used in Europe, as well as in many countries in the Middle East and Asia. GSM is one of several standards by which mobile phones in the United States operate.

The study found that EMF exposure was associated with leakage of albumin through the blood-brain barrier and neuronal damage that increased in response to the amount of exposure. The authors acknowledged that the study sample was small, but stated that "the combined results are highly significant and exhibit a clear dose-response relation."

Earlier EMF studies have focused on whether exposure might cause cancer, with some studies finding increased risk but most showing no effects or even decreased risk.

"Scientists have been looking for some time at the possible effects of exposure to the energy coming out of cell phones," says Dr. Jim Burkhart, science editor for Environmental Health Perspectives. "These scientists decided to look in a new place, studying potential nerve damage, rather than cancer growth. Their results suggest a strong need for further study as we all rely on cell phones more and more."

The study team was headed by Leif G. Salford of the Department of Neurosurgery at Lund University in Sweden. Other authors include Arne E. Brun, Jacob L. Eberhardt, Lars Malmgren, and Bertil R.R. Persson. The study will appear in a future print issue of EHP. EHP is the journal of the National Institute of Environmental Health Sciences, part of the U.S. Department of Health and Human Services. More information is available online at http://www.ehponline.org/.

Editor's note: : A full copy of the report is available by fax or e-mail (PDF format) to media at no charge. Go to www.ehponline.org/press, call 919-653-2585, or e-mail adams6@niehs.nih.gov.

Environmental Health Perspectives Volume 111, Number 7, June 2003

Study Talks
Rat Brain Damage from Mobile Phone Use

The idea that frequent exposure to the electromagnetic fields (EMFs) generated by mobile phones could cause adverse health effects has taken on the status of urban myth in many people's minds due to the lack of definitive scientific evidence. But startling new findings by a team of researchers from Lund University in Sweden make the issue once again a cause for genuine concern--and suggest it might be time to get serious about using your headset when talking on your mobile phone and encouraging your family members to do the same [EHP 111:881-883].

Previous research in the field has concentrated on the potential association between exposure to radio-frequency (RF) EMFs and cancer. Studies with that end point have shown either no effects or even a decreased risk. The Swedish team, led by Leif G. Salford, has taken a different approach, focusing on the possibility that such exposures could cause damage to the brain itself. Prior experiments by the group with a rat model had shown that RF EMF exposure significantly breached the animals' blood-brain barrier. This allowed the plasma protein albumin to pass out of the bloodstream and into the brain, accumulating in the neurons and glial cells surrounding the capillaries. In their new study, the investigators address the question of whether this leakage of albumin could damage brain tissue.

The investigators exposed 32 rats to controlled doses of RF EMF generated by a Global System for Mobile Communications mobile phone (a type commonly used in Europe). The rats were divided into 4 groups and exposed for 2 hours each to power outputs of 0 (control), 10, 100, or 1,000 milliwatts, exposure levels that are roughly comparable to what a human mobile phone user might receive over the same time period. The animals' brains were examined 50 days after the single exposure.

As expected, a large proportion of the exposed rats showed evidence of albumin leakage. In this experiment, however, the Swedish team also found that the albumin appeared to cause significant and serious neuronal damage. "Dark" neurons, which appeared shrunken and homogenized, with loss of discernible internal cell structures, were seen in all locations of the exposed rats' brains, particularly in the cortex, hippocampus, and basal ganglia. The number of dark neurons discovered was significantly and positively associated with the RF EMF dose received by the animals.

The authors acknowledge that their study sample was small, but state that "the combined results are highly significant and exhibit a clear dose-response relation." The rats used were 12-26 weeks old, comparable in age and development to human teenagers, who the authors note are "notably frequent users of mobile phones." As the group points out, the biologic and maturational processes taking place in the growing brain are particularly vulnerable to damage from exposures of this type. Although they admit that neuronal damage like that seen in this study may not have immediately demonstrable consequences, they are worried about the long-term effects of frequent RF EMF exposure: "We cannot exclude that after some decades of (often) daily use, a whole generation of users may suffer negative effects [including reduced brain reserve capacity], perhaps as early as middle age."

Ernie Hood

http://ehpnet1.niehs.nih.gov/docs/2003/111-7/ss.html