Nittby H, Brun A, Stromblad S, Moghadam MK, Sun W, Malmgren L, Eberhardt J, Persson BR, Salford LG. Nonthermal GSM RF and ELF EMF effects upon rat BBB permeability. Environmentalist. Ahead of print. Jan 29, 2011.
The effects of radiofrequency electromagnetic fields (RF-EMF) upon the blood–brain barrier (BBB) have been extensively investigated. A passage of rats’ own albumin from the blood through the brain capillaries into the surrounding brain parenchyma has been repeatedly demonstrated at low levels of radiation however, it is unknown if magnetic fields emitted by fans used in experimental protocols might add to the RF effects.
The objective of this study was to determine whether the extremely low frequency (ELF) magnetic fields from electric fans (50 Hz, 0.3–1.5 lT) used in experimentation might add to RF effects on BBB permeability in rats.
Sixty-four rats (32 males and 32 females) were divided into 4 groups: those exposed to RF only, ELF only, RF + ELF, or no exposure (sham group). Animals were exposed to GSM- 900 MHz at a very low nonthermal average whole-body SAR level of 0.4 mW/kg for 2 h in the same transverse electromagnetic transmission line cell. Immediately after sham or EMF exposure, each animal was anesthetised and brains were dissected. Brains were fixed in situ, dehydrated, embedded in paraffin, and examined histopathologically. Albumin staining was performed using IgG antibodies, avidin, biotin, and DAB (diaminobenzidine).
Although a 3rd staining attempt demonstrated albumin extravasation in the hypothalamus and albumin foci in the brain, in 3 cases there was no staining in hypothalamus, and in most cases, staining was very weak. In total only 23 brains exhibited intense staining. In the sham group, none of the animals had any pathological albumin leakage. The incidence of pathological brains in each of the exposed group was 25% in the RF group, 19% in the ELF group, and 13% in the RF + ELF group. In the RF animals, there was a strong trend (p = 0.05) to increased leakage, while the ELF and RF + ELF groups were not significantly different from the control group (p = 0.10 and p = 0.11, respectively). When all exposed animals (RF, RF + ELF, and ELF) were compared to the sham group, the percentage of animals with albumin leakage was not statistically significantly (p = 0.06).
Interpretation and Limitations
The authors state that despite technical difficulties with the staining procedures, they demonstrated that the use of external fans has no significant effect on pathological albumin leakage in the brain of rats. However, they recognize that their study had several important limitations. First, their sample size of only 64 rats was very small. Second, their staining procedure was problematic. Third, confirmation of the results of this study by another group of researchers was unsuccessful. Finally, short term exposure to RF and ELF in rats is very difficult to extrapolate to long-term biological and/or health effects in humans.
This study suggests that the use of external fans has had no major influence upon rat BBB permeability.