Topic

in vivo experiments on exposure to the high frequency fields of mobile telecommunication.
A. long-term study

Start

01.11.2003

End

30.04.2007

Project Management

EMVU (Technical University and Ludwig-Maximilian University, Munich)

Objective

The objective of this project is to examine the possible effects of chronic exposure to electromagnetic fields from mobile telecommunications systems (GSM and UMTS) in vivo. In order to assess the possible effects on the developing organism, laboratory rodents (Wistar rats) are exposed over the course of three generations. The animals' health condition, reproductive capability and, in particular degree, possible capacity for learning and memory are determined and compared to a sham-exposed group. Influences on the blood-brain barrier and CA1-neurons as well as stress and immune response are examined.

Results

A new setup for long-term exposure of rats in their home-cages to electromagnetic fields (EMFs) of mobile communication was constructed that fulfilled the requirements of exposure specifications and those of the guidelines for animal experiments. It featured defocused parabolic reflectors in three individual exposure chambers (GSM 0.4 W/kg, UMTS 0.4 W/kg, sham) and permitted to expose simultaneously a sufficient number of rats (40 cages per chamber) under quasi-plane wave and high homogeneity conditions. Measurements showed that appropriate shielding provided high isolation levels against external fields and among the individual exposure chambers.

All biological measurements were conducted in three rat generations in a double-blind-design. Male and female rats of the generations F0, F1 und F2 were tested in standardized operant-behavior test chambers by different nocturnal computer-controlled schedules of reinforcement at the age of 10 weeks. The rats of the F0-generation were tested again at the age of 10 months. A multivariate analysis of the experimental results focused on final scores and on the dynamics of test requirement acquisition. The comparison of the different exposure groups and the three generations, however, did not show any significant EMF-induced changes of learning ability or memory.

Reactions of the immune system and of stress parameters as well as the integrity of the blood-brain-barrier (BBB) were investigated in the rats of the F0b and F2 generations after EMF-exposure of 4 months and in the F0a -group after exposure of 11 months.

The specific humoral reaction of the immune system was tested by injection of the antigens Ovalbumin (OvA) and chicken immunoglobulin Y (IgY) in combination with the lipopeptide adjuvant Pam3CysSerLys4. The corresponding antibodies (total IgG, anti-OVA titer, anti-IgY titer) were determined by different specific ELISA-systems. Comparing the different exposure groups (GSM, UMTS, sham) with one exception (total IgG, group F2, GSM > sham, p < 0.05) no significant differences were found.

In order to investigate stress reactions a standardized and well established stressor (ACTH) was applied. Serum corticosterone was measured by an indirect competitive ELISA-system. Only the group F0b showed significantly different stress reactions, which could not be confirmed in the analogously long exposed F2 group and in the longer exposed F0a-group. The results indicate, that chronic exposure with GSM- and UMTS- EMFs does not induce chronic stress.

A quantitative evaluation of the BBB integrity in seven brain areas (bulbus olfactorius, cerebellum, medulla oblongata, pons, mesencephalon, diencephalon and cortex) of the left and right hemispheres was ascertained by the use of the radioactive marker ¹⁴C-saccharose, allowing a high sensitivity of the method. No differences between the unidirectional influx constants (K_in) of the three groups (GSM, UMTS and sham) were found in any of the investigated rat generations (F0b and F2). Neither the longer duration of exposure from four to eleven months (F0a vs. F2), nor the continuous exposure of several generations (F0b vs. F2) did result in significant differences of the of BBB-integrity.