3. Identifying the causes of childhood leukaemia

Low-frequency magnetic fields were already classified as "possibly carcinogenic" (group 2b) by the International Agency for Research on Cancer (IARC) which is associated with the World Health Organization (WHO) in 2001. The classification is based on the statistic association between weak low-frequency fields and a slightly increased risk of childhood leukaemia that has been observed relatively consistently. Since 2008, the BfS has initiated several international workshops, partly in cooperation with the WHO, the International Commission on Non-Ionizing Radiation Protection (ICNIRP) and other national radiation protection authorities or panels. In 2010, an interdisciplinary research agenda aimed at identifying the complex causes of childhood leukaemia, was drawn up together with paediatric oncologists. On the basis of the published research agenda, some of the main topics were selected and corresponding pilot projects were launched. The findings of 5 pilot studies have been published and suggest follow-up research projects as the next steps.

Research projects

3.1. Meta-analysis of the association between childhood leukaemia, exposure to magnetic fields and low-level ionising radiation

There are several recent epidemiological studies on childhood leukaemia and exposure to magnetic fields, and also on low-level ionising radiation (gamma radiation and natural radon exposure). The meta-analysis will provide an evaluative summary of all existing studies.

3.2. Pooled analysis of childhood leukaemia and exposure to magnetic fields

Recent study findings from several countries justify updating the existing analyses, the data from which served as a basis for the IARC classification "possibly carcinogenic" in 2001.

3.3. Molecular genetic analysis ("deep sequencing") of B-cell ALL patients

New sequencing techniques provide not only detailed insights into the molecular genetic background of diseases but also into environmental risk factors. The demanding project will reveal if exposure to magnetic fields is reflected in genome, exome, methylome, transcriptome or miRNome.

3.4. Investigations of the occurrence of leukaemia in suitable animal models

A mouse model reflecting the preleukaemic condition of a human acute lymphocytic leukaemia has only recently become available. This model will be used to test experimentally whether weak magnetic fields (or other environmental noxae as well) can cause leukaemia.

3.5. Investigations of the immune status of animal models exposed to magnetic fields

It has also long been suspected that a weakened or immature immune system is a (contributory) cause of childhood leukaemia. The new mouse model will clarify whether the magnetic field effects on cytotoxic T cells observed in pilot studies can be confirmed. The project is currently being carried out at the Fraunhofer Institute of Toxicology and Experimental Medicine (ITEM) lasting from 1 December 2016 to 30 September 2019.

3.6. Participation or involvement in international consortia dealing with the causes of childhood leukaemia

Childhood leukaemia is not only a complex, but also a rare disease that requires interdisciplinary and international cooperation in order to gain further knowledge. The BfS is in contact with CLIC (Childhood Leukemia International Consortium), I4C (International Childhood Cancer Cohort Consortium) and the new paediatric oncology network GALnet (The Global Acute Leukemia network).

3.7 International Workshop on the current state of research on the aetiology of childhood leukaemia

Since 2008, the BfS has been regularly organising international workshops on the state of research on the aetiology of childhood leukaemia, partly in cooperation with the WHO, ICNIRP or other national radiation protection authorities. It was already the 5th international workshop that was held in November 2016; another workshop on the exchange of current knowledge is to be held in about 2-3 years.

3.8. Involvement in a national birth or mother and child cohort

A prospective cohort can provide answers to many health-related issues and can also address issues and knowledge gaps arising only in future. Should the various interests in environmental and health care lead to a timely establishment of a birth cohort or also a mother and child cohort, it would be useful to record the exposures from static, low- and high-frequency magnetic fields as well.

Outcome of the online consultation