Science Selections June 2003
Authors: E Hood
Journal: Environmental Health Perspectives (2003)

Rat Brain Damage from Mobile Phone UseThe 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 concernand 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