AFRL Research Confirms Safety Standards for RF Devices

  • Published
  • By Christina Wooten, AFRL/RHOR
  • Human Effectiveness Directorate
WRIGHT-PATTERSON AIR FORCE BASE, Ohio --  In the 1990s, researchers affiliated with the University of Lund, Sweden, conducted basic research seemingly refuting safety standards governing radio frequency (RF) emissions. The study indicated that RF radiation emitted at cell phone frequencies and power densities below levels considered safe nonetheless posed a human health hazard. Specifically, the results showed that the low-dose emissions caused large proteins to leak across the blood-brain barrier, a semipermeable membrane that protects the brain from foreign substances in the blood. Consequently, AFRL began leading an international consortium of laboratories in an effort to replicate the Swedish studies and determine if the effects were real. With the AFRL-led studies now complete, the US, French, and Japanese laboratories involved in the effort have failed to produce the same effects as the Swedish labs, effectively confirming the validity of current RF safety standards. 

Possible explanations for the Swedish results include errors in RF dosimetry, stress on test subjects, and artifacts in the histological staining processes used for postexposure evaluation. Based on the more recent results, the scientifically accepted view holds that blood-brain barrier leakage does not occur with exposure below established safe levels. The AFRL-led research thus validates current RF safety standards, maintains confidence in RF weapon system effectiveness, and negates the need for extensive and costly changes to military RF devices such as radars, radios, and telephones. 

Blood-brain barrier leakage, which can cause the brain's temperature to increase to 42°C or 43°C, is scientifically proven to occur with much higher RF exposure levels. However, lower power densities have no historical association with this harmful phenomenon. Scientists acknowledge that the accuracy of RF bioeffects research is susceptible to the influence of artifacts in the process. This vulnerability arises not only from the complicated nature of RF research equipment, but from the unavoidable variability of the stress response exhibited by different biological organisms. In such studies, therefore, it is not unusual for effects to appear that are later proven to be the result of experimental error. Unchallenged scientific acceptance of the Swedish study would have prompted unnecessary lowering of acceptable RF exposures as defined in standards established by the Institute of Electrical and Electronics Engineers and the International Commission on Non-Ionizing Radiation Protection. In turn, the falsely lowered emissions threshold would have needlessly increased keep-out zones, limited the use of US military RF devices in Europe, and otherwise negatively affected Department of Defense operations and commercial RF applications alike.