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Scientifically debated biological and health effects of low-frequency electric and magnetic fields

  • There are scientifically proven health effects of electric and magnetic fields above the limit values.
  • Below the limit values, there are indications of possible effects of low frequency fields which have been the subject of intensive research for some time.
  • So far, the indications of possible health effects below the limit values have not been scientifically proven.

Above the applicable limit values, powerful electric and magnetic fields can be detrimental to health. Scientists are continuously investigating whether, in addition to these demonstrated effects, low-frequency fields could have other effects on health – even below the limit values.

Research on whether low-frequency fields have an impact on various biological endpoints, such as the immune system or the nervous system, is continuously being conducted. This work is also investigating whether low-frequency magnetic fields trigger neurodegenerative diseases or can promote cancer growth and includes carrying out not only epidemiological studies on the population but also animal studies and studies on cells.

What are epidemiological studies?

Epidemiological studies examine the distribution of diseases in a population and the factors that influence this distribution. Although they can reveal statistical relationships, such relationships needn’t necessarily indicate a causal relationship. It is therefore important to supplement the results of epidemiological studies with experimental studies – that is, studies of human subjects, animals or cell cultures.

What must studies take into account?

There are two aspects that must be taken into account when it comes to investigating the biological effects of low-frequency fields in animal studies or in laboratory studies on cells. Firstly, studies must consider whether the observed effects could be independently validated – i.e. confirmed. Although many results from individual working groups have demonstrated biological effects, other working groups have not been able to confirm these findings. Secondly, it is often unclear whether the results from animal or cellular studies are applicable to people – and, therefore, whether the effects are relevant to human health.

Answering unresolved questions through the research programme “Radiation Protection in the Process of Power Grid Expansion”

The energy transition is associated with an expansion of power grids in Germany, which is likely to result in increased exposure of the population to low-frequency electric and magnetic fields. To reduce existing scientific uncertainties in the risk assessment of low-frequency fields and to answer unresolved questions, the BfS is carrying out a research programme entitled “Radiation Protection in the Process of Power Grid Expansion”. Numerous research projects are being conducted in a total of 11 subject areas.

Neurodegenerative diseases in adultsShow / Hide

Neurodegenerative diseases are generally slow-progressing diseases of the nervous system that involve the progressive loss of nerve cells, often leading to dementia and/or motor disturbances. Some epidemiological studies point to an increased incidence of neurodegenerative diseases in the event of high (occupational) exposure to low-frequency electric and magnetic fields. Several – but not all – existing studies have identified a statistically significant relationship between occupational exposure and Alzheimer’s as well as amyotrophic lateral sclerosis (ALS, a type of muscle weakness). It is not clear, however, whether this is a causal relationship and what mechanisms of action are behind it. The risk of developing Parkinson’s or multiple sclerosis did not increase due to occupational exposure to low-frequency magnetic fields.

There have also been studies of the general population – that is, of people not occupationally exposed to such fields. An epidemiological study from Switzerland, which was based on very low case numbers, showed an increased risk of Alzheimer’s in people who lived less than 50 m from a high-voltage power line. Later studies from Denmark and Italy were unable to confirm these results. An analysis of five epidemiological studies showed no relationship between high-voltage power lines and ALS.

Results of epidemiological studies not yet confirmed by laboratory studies

It has not yet been possible to confirm the results of epidemiological studies through experimental laboratory studies. Likewise, no biological mechanism of action has so far been found that could explain or scientifically corroborate the study findings. Nevertheless, scientific research is ongoing into possible relationships between low-frequency fields and diseases of the nervous system.

In order to clarify a potential relationship between low-frequency fields and neurodegenerative diseases, the BfS has sponsored an experimental study of Alzheimer’s dementia and amyotrophic lateral sclerosis using genetically modified mouse models. The animals were exposed to a low-frequency magnetic field for their entire lives. In tissue analyses and behavioural tests, the fields were not found to negatively influence the course of these diseases in these mice.

Further research into the relationship between low-frequency magnetic fields and neurodegenerative diseases is being carried out as part of the research programme “Radiation Protection in the Process of Power Grid Expansion”.

Cancers in adultsShow / Hide

Since the end of the 1970s, researchers have been investigating a possible link between low-intensity low-frequency fields and cancers, including as part of epidemiological studies. In adults, researchers have found no proof of an increased risk of cancer in the event of prolonged exposure to low-frequency fields.

Childhood leukaemiaShow / Hide

The situation is different when it comes to leukaemia in children. A number of epidemiological studies have consistently identified a slightly – but significantly – increased risk of leukaemia in children who are exposed to magnetic fields significantly below the limit value over a prolonged period of time. Most of these studies examined the total residential exposure to magnetic fields. Although high-voltage power lines close to a person’s home can contribute part of this exposure, they account for a relatively small share in most homes in Germany. The larger contribution usually comes from household wiring and electrical appliances.

As an average over the day, the magnetic field exposure above which an increased leukaemia risk was observed is approximately 0.3 to 0.4 microteslas (µT). Such values are rare in German homes. In a study sponsored by the BfS, median magnetic field exposures ≥ 0.2 µT were only measured in 1.4% of the children’s rooms that were analysed. The increased exposure could only be attributed to high-voltage power lines in just over a third of these rooms.

Magnetic field exposure Magnetic field exposureMagnetic field exposure in children's bedrooms

Childhood leukaemia is a rare disease

Childhood leukaemia is a relatively rare disease. Of 100,000 children under the age of 15, some five develop leukaemia each year; in other words, there are approximately 600 new cases a year in Germany. As only a small number of children are exposed to magnetic fields stronger than 0.3 microteslas, the epidemiological studies are based on relatively small numbers of cases. It is therefore all the more important to supplement the results of epidemiological studies with experimental laboratory studies.

A study sponsored by the BfS found that, in Germany, approximately 1% of leukaemia cases in children could be explained by increased exposure to low-frequency magnetic fields if there was actually a causal relationship (see final study report).

As early as 2002, low-frequency fields were assigned to group 2B (“possibly carcinogenic”) by the International Agency for Research on Cancer (IARC), which is connected to the World Health Organization (WHO). Here, key factors included the aforementioned epidemiological observations of a statistical association between childhood leukaemia and a time-averaged magnetic field exposure of children in the range of more than 0.3–0.4 µT. The possible risk to children due to low-frequency magnetic fields must therefore be taken very seriously and highlights the need for further research activities.

Cause-and-effect relationship

The evidence from epidemiological studies is not enough to be seen as proof of a cause-and-effect relationship. Likewise, no biological mechanism of action has yet been identified that would explain the development of leukaemia or the promotion of leukaemia cell growth as a result of low-frequency magnetic fields. So far, animal studies have also failed to support the evidence from epidemiological studies.

Scientific investigations therefore continue to examine whether magnetic fields are actually involved in the development of childhood leukaemia. In general, there is still insufficient knowledge regarding the causes of this disease. It is currently assumed that it develops due to a combination of various genetic and environmental factors. However, in addition to low-frequency magnetic fields, discussions regarding childhood leukaemia also include various other environmental risk factors (e.g. air pollution or pesticide exposure) and genetic risk factors. Here, too, it is important to carry out targeted research in order to further clarify the causes.

Research into the causes of childhood leukaemia

The KiKK study, also sponsored by the BfS, yielded another finding that is relevant to radiation protection and cannot be explained by current scientific knowledge of the effects of radiation – specifically, a link between the proximity of the place of residence to a nuclear power plant and the risk of childhood leukaemia. Accordingly, it is necessary to intensify the search for the causes of leukaemia in children in order to improve our understanding of the interaction between genetic and environmental factors in the disease’s development. The BfS is committed to an extensive programme of research aimed at clarifying these relationships and has therefore worked with international experts to draw up a research agenda and carry out five pilot studies. The results of these pilot studies have been published in the BfS’s Digital Online Repository and Information System (DORIS) and suggest that research should continue to follow these new, interdisciplinary approaches. You can find further details of research into the causes of childhood leukaemia and the implemented pilot projects here.

The BfS organises regular workshops at the international level with a view to continuously monitoring scientific progress. From 20 to 23 November 2019, it hosted the 6th International Workshop on the Causes of Childhood Leukaemia. A summary and discussion of the workshop’s results were published in the journal Frontiers in Public Health.

Based on the results of the pilot studies and the workshops, further research is underway into childhood leukaemia as part of the research programme “Radiation Protection in the Process of Power Grid Expansion”.

ElectrosensitivityShow / Hide

Some 1% of the population of the Federal Republic of Germany describe themselves as being electrosensitive – in other words, they attribute various complaints (e.g. headaches, sleep disorders, fatigue, concentration problems) to the presence of electromagnetic fields in their environment. For a long time, complaints related primarily to low-frequency electric and magnetic fields. Since the rapid expansion of mobile communications, however, high-frequency fields are increasingly also cited as the cause of such complaints.

The phenomenon of “electrosensitivity” has been and continues to be the subject of numerous scientific studies (e.g. as part of the German Mobile Telecommunication Research Programme). Above all, the aim of this research is to objectivise the complaints and clarify the causal relationships that affected individuals suspect exist between electromagnetic fields and adverse effects on health. So far, however, it has not been possible to establish a sound scientific basis for the relationships suspected by those affected. For example, a research project supervised by the BfS revealed that electrosensitive individuals are less capable than control subjects of distinguishing genuine magnetic impulses from sham pulses. On the other hand, such complaints may arise due to knowledge of the presence of fields in conjunction with concerns around the possible health effects of these fields. This mechanism of action is referred to as the nocebo effect – the opposite of the placebo effect – and is presumably also involved in the development and above all the maintenance of electrosensitivity.

Causal relationship between electromagnetic fields and the complaints of electrosensitive individuals very likely ruled out

One conclusion to emerge from the numerous studies carried out so far is that a causal relationship between electromagnetic fields and the complaints of electrosensitive individuals can very likely be ruled out. This assessment is also shared by the WHO. In a backround paper in Dezember 2005, it took the view that there is no scientific basis for linking the symptoms of electrosensitive individuals with the influence of electromagnetic fields. This view was substantiated in 2015 as part of the risk assessment of electromagnetic fields by the Scientific Committee on Emerging and Newly Identified Health Risks (SCENIHR). For this reason, the BfS is not carrying out any further research projects on the subject of electrosensitivity.

State of 2023.12.05

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