Topic

Influence of electromagnetic fields of mobile communication on the metabolic rate in rodents

Start

22.12.2006

End

31.01.2008

Project Management

Jacobs University Bremen

Objective

In the project "Influence of low and high frequency electromagnetic fields on spontaneous leukaemia in AKR/J mice" a slight but significant increase of the relative body weight of the animals under exposure with GSM-900, SAR 0.4 W/kg, was observed. This follow up project should investigate, whether the metabolic rate of rodents is influenced by the RF-exposure.

Results

The aim of this project was to clarify if previously documented effects on body mass in GSM-exposed animals may be due to metabolic effects below thermal threshold. Male Djungarian hamsters (Phodopus sungorus) were continuously sham-exposed or exposed for one week to GSM-type electromagnetic fields at SAR levels of 0 (sham), 0.08, 0.4, or 4 W/kg, while carbon dioxide production and oxygen consumption were recorded in the exhaled air. Once per day temperatures of fur and eyes were recorded non-invasively by means of infrared thermography to assess heat loss through the skin and a surrogate for body core temperature, respectively. The results demonstrate the suitability of the experimental design. Effects of exposure were seen only at the highest SAR level of 4 W/kg. Four temperatures were found to be significantly elevated by approximately 0.5 °C which indicates an exposure-related increase of heat loss through the skin. The temperatures of the eyes, however, were unaffected indicating that the absorbed energy could be compensated without effects on core temperature by increased heat loss through the skin. Only at 4 W/kg a significantly decreased food consumption was observed while the consumption of water was unchanged. Effects on carbon dioxide production were observed only at highest exposure levels with significantly decreased levels during the day. Also the respiratory quotient was slightly, but significantly reduced during the day at 4 W/kg. The final report is available as (4.390 KB) in German, technical section in English (see annex).

The observed effects on temperature, food consumption and reduced carbon dioxide production appear only at 4 W/kg, i. e. in a region, where the body temperature is not yet increased, but thermal regulation is already active. It seems possible that a reduction in metabolic activity helps avoiding an increase of body temperature. But because no effects were observed on the endpoints which had been chosen to detect metabolic effects of low SAR levels of 0.08 W/kg and 0.4 W/kg, the results can neither give a convincing explanation for the increase of body weight observed in AKR-mice (http://www.emf-forschungsprogramm.de/forschung/biologie/biologie_abges/bio_040.html) nor support the hypothesis of metabolic effects at SAR levels below the thermal regulatory threshold of the animals. It should also be mentioned that no weight gain was observed for GSM 900, SAR 0.4 W/kg in a 3 generation study in rats (http://www.emf-forschungsprogramm.de/forschung/biologie/biologie_abges/bio_050.html). Nevertheless a systematic control of weight and food consumption should be taken into account particularly in long-term in vivo studies with chronic exposure.