The EMF to BBB connection

The author considers the effects of electromagnetic energy on the blood-brain barrier (BBB). The integrity of the BBB is necessary for proper function of the brain in mammals. Minor leakage of the BBB can lead to neural dysfunction and major leakage is associated with brain swelling, which can lead to death. Thus, any change in the BBB of humans by EM fields could cause significant adverse effects. It is well established that RF heating of the brain by several degrees will cause gross and easily detectable disruption of the BBB. Such exposure is far above recommended safety limits and would be clearly hazardous to a person for other reasons as well. This level of exposure is unlikely to occur from environmental or occupational exposures to microwaves, low frequency fields, or from MRI scanners. It may be a factor in hyperthermia treatment of brain cancer. It is far less clear that EM fields have any effect on the BBB, apart from those resulting from gross brain heating. Roughly an equal number of studies using low-level (nonheating) exposures to either RF or low frequency fields have reported effects as have found no effects. In retrospect, it is clear that any effect from such exposure is small. To measure reliably a small breakdown of the BBB in the face of biological and experimental variability requires quantitative techniques tailored for measurement of small changes in transcapillary transport. Such a study has never been carried out.