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Effects of low frequency magnetic fields on the hematopoietic system, the immune system and the central nervous system

  • The question of whether low-frequency fields have an effect on the haematopoietic system, the immune system and the central nervous system was investigated in animal experiments as part of a research project commissioned by the Federal Office for Radiation Protection (BfS).
  • A transient decrease in the number of a certain type of immune cells (CD8+ cytotoxic T cells) was observed in the mice studied at meoderate and high levels of exposure to low-frequency fields (50 Hz). However, higher tumor rates than in the control animals did not occur in the exposed animals.

Since 2002, the International Agency for Research on Cancer (IARC) has classified low-frequency magnetic fields as class 2B "possibly carcinogenic". The IARC is part of the World Health Organization (WHO).

The results of epidemiological studies are decisive for the classification of low-frequency magnetic fields as "possibly carcinogenic". A statistical association was found between exposure to low-frequency magnetic fields above a threshold of about 0.3 to 0.4 µT (averaged over time) and childhood leukemia (see Scientifically discussed effects of low-frequency fields).

Verification of the indications from epidemiological studies in animal models is necessary

The informative value of epidemiological studies can be limited by methodological problems such as a possible selection bias (an error that can result, for example, from inadequate selection of subjects for a study), insufficient exposure recording and low case numbers. Animal studies do not currently support the evidence from the epidemiological studies. However, hardly any animal experimental work captures the early developmental phases of the animals.

Research project at the Fraunhofer Institute for Toxicology and Experimental Medicine

In order to shed more light on some of these open questions, the Federal Office for Radiation Protection commissioned the research project "Effects of low frequency fields on the developing hematopoietic system, the immune system and the CNS in vivo" at the Fraunhofer Institute for Toxicology and Experimental Medicine (ITEM) in Hanover. The project should clarify whether pre- and postnatal exposure of laboratory animals (mice) to low frequency magnetic fields (50 Hertz (Hz)) has an impact on the developing hematopoietic system, the immune system and the CNS with the main focus on neoplasias of the hematopoietic system.

Subsequently, the influence of chronic exposure to low-frequency fields (50 Hz) on the developing haematopoietic system, the immune system and the central nervous system as well as on sexual maturation and the development of reflexes was examined in an animal model (CD1 mice). Animals were exposed already before birth and up to the age of 18 months.

The focus of the research project was the question of whether the risk of cancer of the blood-forming system increases when the animals are exposed to low-frequency magnetic fields.

Results

Exposure-related effects on the development of the central nervous system were not observed. The development of reflexes and the sexual maturation of the animals were not negatively influenced by the exposure either.

A reduction of cytotoxic T-cells/suppressor cells was seen in peripheral blood and spleen in middle (1mT) and high (10 mT) dose groups at day 90. Increased lymphocyte counts and decreased counts of banded neutrophiles were seen after 18 months of exposure, but the results of the histopathological examination did not display any exposure related alterations, especially neither for neoplastic nor for non-neoplastic lesions.

Literature study

At the beginning of the project a literature study has been performed which compiles and evaluates the scientific literature on the impact of ELF exposure mainly on the hematopoietic system and the CNS in animals and man.

You can download the literature review (in German, foreword and summary in English) at the BfS online repository DORIS.

Final report

The main part with summary and conclusion and the annex of the final report can be downloaded (in German, summary and conclusion in English) at the BfS online repository.

Follow-up study

In order to further investigate the observation of a reduced number of immune cells after exposure to low-frequency magnetic fields, the research project Investigations of the immune status of animal models exposed to magnetic fields was initiated in the research program Radiation protection in the Process of power grid expansion. In this experimental study on mice, it will be investigated whether their immune cells are affected in their appearance (phenotype) and their function by exposure to low-frequency magnetic fields. The focus of the study is on possible effects of exposure on the developing immune system in young animals that are exposed prenatal and after birth up to a maximum age of four weeks. The mouse model used (Sca1-ETV6-RUNX1 mice) carries a leukemia-specific genomic alteration that is common in humans. The project was awarded to the Fraunhofer Institute for Toxicology and Experimental Medicine (ITEM) in Hanover in 2016.

State of 2022.09.12

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