Navigation and service

Research programme of the Federal Office for Radiation Protection on "Radiation Protection in the Process of Power Grid Expansion"

Mensch und Strom Auswirkungen des Stroms auf den Menschen

In order to increase the share of renewable energy in power supply, it is necessary to expand and to upgrade existing electricity grids. To this end, not only existing alternating current power lines are uprated, but also new alternating current power lines and high-voltage direct current power lines (HVDC lines) are installed, the latter for the first time and preferably as underground cables. The attitudes of a part of the population affected by the expansion range from being critical to disapproving of the necessary measures. Among the reasons put forward are concerns about health risks.

In the process of expanding the power grid, issues concerning health and radiation protection have to be considered from the beginning. The Federal Office for Radiation Protection (BfS) is making an important contribution with its research programme on "Radiation Protection in the Process of Power Grid Expansion".

Protection by existing limit values - open questions have to be followed up

The limit values set in the Federal Immission Control Act (26th BImSchV) provide protection against all established health risks from static and low-frequency electric and magnetic fields posed by electricity lines. However, there are scientific indications for potential health effects below existing limit values and other open questions that have to be addressed in the research programme "Radiation Protection in the Process of Power Grid Expansion".

Currently, there is no satisfactory explanation for the statistical association between the exposure to low-frequency magnetic fields and childhood leukaemia observed in several studies. Indications of an association between exposure to low-frequency magnetic fields and the occurrence of degenerative diseases of the nervous system (e.g. amyotrophic lateral sclerosis/ALS, Alzheimer's dementia) cannot be finally assessed at present either. In the case of HVDC overhead lines, especially questions about an increased perception or perceptibility of electric fields and questions about a possibly enhanced effect of corona ions cannot be answered satisfactorily with current scientific knowledge.

Research is aimed at reducing uncertainties in risk assessment

In order to reduce scientific uncertainties in risk assessment and to be able to answer open questions, the Federal Office for Radiation Protection (BfS) will conduct an accompanying research programme "Radiation Protection in the Process of Power Grid Expansion". 36 individual research projects in eight topic areas altogether will be conducted.

Projects for determining the current state of scientific knowledge and also contributing to the specification of research questions for further projects such as workshops and literature reviews, have either already started, have been conducted or are planned for the near future.

Topic areas

1. On the clarification of possible associations between low-frequency magnetic fields and neurodegenerative diseasesshow / hide

Neurodegenerative diseases are disorders of the central or peripheral nervous system in which nerve cells degenerate and die. This leads to dysfunction in the brain (e.g. memory disturbances, dementias) and the musculoskeletal system (e.g. multiple sclerosis/MS, Parkinson's disease, amyotrophic lateral sclerosis/ALS).

Epidemiological studies (human observational studies) have been conducted, showing an association between high exposure to magnetic fields and ALS or Alzheimer's dementia in occupationally highly exposed groups of individuals. For Alzheimer's dementia, one study revealed an additional indication of an association with residential proximity and duration of residence near to high-voltage power lines. In contrast to this, the results of epidemiological studies show no association between exposure to magnetic fields and Parkinson's disease or MS. Experimental animal studies have not yet been able to confirm the epidemiological findings; no action mechanism is known either.

Recent epidemiological data and their summary analyses are to be used to update the data on a possible association between neurodegenerative diseases and magnetic fields or also electric shocks. If the findings made so far are confirmed, the causality of the association will be verified in animal studies and studies with cell cultures, and possible action mechanisms will be investigated.

Research projects

1.1. Meta-analysis of the association between neurodegenerative diseases and exposure to magnetic fields

There have been several new publications since the last meta-analysis of occupational exposure to magnetic fields and neurodegenerative diseases. The literature review will provide a summarizing risk assessment of all existing studies that will have been published in the meantime, with the quality and power of the studies being evaluated using a standardised procedure.

1.2. Pooled analysis of the association between ALS and exposure to magnetic fields

More recent epidemiological studies also investigated the association between ALS and electric shocks in addition to magnetic fields in the affected occupational groups. However, the data are very inconsistent. The original data from high-quality studies on ALS will be analysed statistically, thus allowing firm statements about the risk. Various exposure scenarios (medium exposure to magnetic fields, electric shocks etc.) will be considered in the process.

1.3. International Workshop on the association between neurodegenerative diseases and exposure to magnetic fields

A workshop with invited experts is the quickest possibility to gain an overview of the current state of research and knowledge gaps which may serve as a basis for targeted research projects (projects 1.4 to 1.7).

The international workshop is scheduled for 12 to 14 December 2017 in Munich.

1.4. Effects of low-frequency magnetic fields on the development and progression of ALS in animal models (in vivo)

Based on the results of the workshop and the literature review, suitable animal models and endpoints to be investigated will be chosen and animal experiments using exposure to low-frequency magnetic fields will be conducted.

1.5. Effects of low-frequency magnetic fields on the development and course of Alzheimer's dementia in animal models (in vivo)

Based on the results of the workshop and the literature review, suitable animal models and endpoints to be investigated will be chosen and animal experiments using exposure to low-frequency magnetic fields will be conducted.

1.6. Mechanisms of action of low-frequency magnetic fields in the development of ALS in cell cultures (in vitro)

Based on the results of the workshop and the literature review, suitable cell lines (or samples from the in vivo studies) and endpoints to be investigated will be chosen and laboratory studies with cells exposed to low-frequency magnetic fields will be conducted.

1.7. Mechanisms of action of low-frequency magnetic fields in the development of Alzheimer's dementia in cell cultures (in vitro)

Based on the results of the workshop and the literature review, suitable cell lines (or samples from the in vivo studies) and endpoints to be investigated will be chosen and laboratory studies with cells exposed to low-frequency magnetic fields will be conducted.

2. Determination of perception and effect thresholdsshow / hide

Electric and magnetic fields, as produced by power lines, may possibly be perceived and experienced as unpleasant. Low-frequency magnetic fields induce electric currents in the body which stimulate nerves and muscles when limit values are exceeded. Static electric fields from HVDC overhead lines can be directly perceived at high field strengths. Moreover, metal objects such as cars which are located underneath power lines can become electrically charged. Spark discharges or contact currents may occur if an individual comes into contact with the metallic surface of a car.

Research projects

2.1. International Workshop on the effect and perception thresholds of static and low-frequency magnetic and electric fields and contact currents in humans

The workshop was held on 26/27 October 2016 in Munich. Leading experts in this field were present. They gave overviews of the current state of research. The discussion following each overview served to identify knowledge gaps and research priorities allowing to specify the planned research projects.

2.2. Effect and perception thresholds of static electric fields

An experimental study on subjects will investigate the thresholds above which and owing to which mechanism of action, electric fields are perceived and above which values the perception is experienced as annoying, unpleasant or painful. The presumed perception by means of body hair will be tested. Individual differences, age and gender dependency as well as the influence of external factors such as temperature, humidity, ionisation and clothing will be considered.

The study "Determination of human perception threshold in static electric fields from high-voltage direct current (HVDC) transmission lines" is currently conducted at the RWTH Aachen University. The study planned here is intended to validate and extend the findings.

2.3. Effect and perception thresholds of contact currents and spark discharges in the case of high-voltage direct current and high-voltage alternating current

An experimental study on subjects will clarify the threshold values above which spark discharges and contact currents are perceived and experienced as unpleasant or painful. The study will provide data on individual variability as well as on gender and age dependency.

2.4. Effects on the central and peripheral nervous system due to low-frequency electric fields induced in the body

The project will investigate above which thresholds electric currents induced in the body by low-frequency magnetic fields may influence the central and peripheral nervous system of subjects under partial or whole body exposure. Influences on brain activity that cannot be perceived subjectively will be measured and perceptible stimuli will be queried. The threshold values at which modulation of neuronal activity in the brain takes place and the thresholds above which perceptions and sensations are experienced as unpleasant will be determined. Individual variability as well as gender and age dependency will be considered. This project is intended to verify the reliability of already existing data and to specify the threshold values only roughly known so far.

3. Identifying the causes of childhood leukaemiashow / hide

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.

4. Investigation of the co-carcinogenicity of exposure to magnetic fieldsshow / hide

Animal studies and in vitro studies on co-carcinogenicity have been classified as high priority by the WHO (2007). A recent study by Soffritti et al. (2016) on Sprague-Dawley rats with lifelong exposure (prenatal to natural death) to 20µT or 1mT 50-Hz fields and one additional exposure to a dose of 0.1 Gy of ionising radiation at the age of 6 weeks, revealed a significantly increased morbidity for several types of tumours. The possible co-carcinogenic effect of magnetic fields is to be verified.

Research project

Investigations of the co-carcinogenicity of exposure to magnetic fields

Within this research project the possible co-carcinogenic effect of magnetic fields is to be verified.

5. Investigation of the possible association between exposure to magnetic fields and the rate of miscarriageshow / hide

On account of some indications concerning occupational and residential exposure to magnetic fields (e.g. from using electric blankets), this endpoint was included in the WHO Research Agenda although the evidence is classified as very weak. Even a weak association would overall have far-reaching significance, meaning that improving the data is desirable.

Research project

Epidemiological study on the association between exposure to magnetic fields and an increased risk of miscarriage

This epidemiological project is aimed at analysing the risk of miscarriage in an already existing cohort using available data on residential and/or occupational exposures to magnetic fields.

6. Investigations of the occurrence, propagation and absorption of corona ionsshow / hide

Due to the corona effect observed at high-voltage power lines, air molecules and particles around overhead lines are charged electrically and are then blown sideways by the wind for instance. A hypothesis that such charged particles increase the risk of respiratory diseases in residents living near high-voltage power lines was developed in 1996 in England. There is no scientific evidence for this assumption. The British radiation protection authority (National Radiological Protection Board/NRPB) addressed this question in 2004. An additionally increased health risk from air pollutants due to charged particles around conventional high-voltage alternating current lines was considered unlikely or very low.

As it is assumed that the charge clouds generated by HVDC lines exhibit increased stability over time and as a consequence can expand further than those generated by HVAC lines, the hypothesis is gaining new significance. The question whether air pollutants emanating from the subsoil (such as radon and its decay products), industrial processes or traffic are increasingly absorbed by the body depending on their electric charge state and thus represent a higher health risk, has yet to be clarified.

Research projects

6.1. Evaluative literature review of the occurrence and the propagation of corona ions

The state of scientific knowledge on the formation, concentration and propagation of ionised air molecules and dust particles will be determined. A comparison between conventional HVAC transmission lines and the planned HVDC transmission lines has to be performed also depending on the weather conditions. Potential health risks will be investigated, knowledge gaps identified and research approaches as well as appropriate investigation methods will be suggested.

6.2. Detection and propagation of corona ions in the surroundings of overhead power lines

Measurement and calculation methods to determine the formation and propagation of corona ions (in the case of direct and alternating current) will be used based on the literature review. Air pollution and weather factors will be considered.

6.3. Numerical calculation of the absorption of ionised particles by the lungs

Model calculations will be used to determine the effects of ionisation on the deposition of particles in the lungs. Particle size, positive or negative charge and the number of charges are to be considered.

6.4. Measurements of the absorption of ionised particles on lung phantoms

Measurements on lung phantoms are used to determine the effects of ionisation on the deposition of particles in the lungs. Particle size, positive or negative charge as well as other accompanying factors such as temperature, humidity and anatomical and physiological parameters are considered.

7. Exposure analysis, exposure assessment and current data on the exposure of the general publicshow / hide

The electric fields and currents induced in the human body during exposure to low-frequency fields can partially be determined only with large uncertainties. Thus, the independent Scientific Committee on Emerging and Newly Identified Health Risks (SCENIHR) of the European Union points out, for example, that data and systematic studies on the dielectric properties of tissues at low frequencies are lacking. In its Research Agenda for low-frequency fields, the WHO recommends improving dosimetric models for tissue and tissue structures which are particularly sensitive to induced electric fields. Even technical professional associations such as IEEE/ICES have identified research needs in this context. To this end, a contribution is to be made.

When constructing and substantially modifying electrical power supply facilities, - for precautionary reasons - attention should be given to ensure that public exposure is not significantly increased. Investigations of low-frequency magnetic fields in Germany conducted mainly before 2000, revealed time-averaged exposures of about 0.1 microtesla. These data are to be updated.

Furthermore, electrical power supply facilities have to be operated in a way that considerable nuisance due to contact voltages (contact currents, discharge upon touching charged, ungrounded objects) and spark discharges is prevented (information on the implementation of the Ordinance on Electromagnetic Fields, Federal/Länder Working Group on Immission Protection, 2014). The occurrence of these effects is to be investigated more closely.

Research projects

7.1. Developing and refining dosimetric models for exposure analysis and assessment

The data on the electrical properties of organs and tissue structures are to be further improved. The data are intended for a better prediction of the internal field strengths actually occurring when external electric or magnetic fields act upon tissue.

7.2. Recording the general public's exposure to magnetic fields

Current data on the exposure of the general public are to be recorded using personal dosimeters. Random measurements in the vicinity of new or uprated lines are also planned.

7.3. Investigations of the occurrence of spark discharges and contact currents

The occurrence of contact currents in daily life, especially in the vicinity of power supply facilities, is to be investigated. On account of the expected higher ground field strengths, HVDC installations are to be included into the analysis as far as possible. Moreover, dosimetric models for various scenarios and population groups are to be developed which can be used for specifying the electric field strengths for the various tissues within the body when spark discharges and contact currents occur.

7.4. Determining the electric fields of overhead power lines

Measurement and calculation methods to determine the exposure to the electric fields of high-voltage overhead power lines (direct and alternating current) are to be developed and tested.

8. Risk perception and risk communicationshow / hide

In addition to aspects of nature conservation, environmental protection and disfiguration of the landscape, discussions and media coverage are characterised by questions on the health risks from static and low-frequency fields. Emotions and fears among the public play a fairly significant part.

The issue concerning the technical design of power supply installations and also the potential health risks from electric and magnetic fields, is very complex. That is why it is difficult for the citizens to maintain an overview of and to assess all related aspects. Moreover, authority staff and elected political representatives often do not have sufficient expertise to be able to answer all questions competently.

In this part of the research programme, the citizens' knowledge and risk perception and the public's need for information is determined. On that basis, it will be clarified how information has to be prepared and how and by whom it should be conveyed in order to reach the widest possible public.

The programme also investigates which factors are decisive for public opinion formation and how the credibility of the involved authorities and the confidence in the individuals acting on their behalf can be ensured or enhanced.

The projects in the scope of the research priority of risk communication are intended to counterbalance the citizens' uncertainty about the health effects of electricity lines. The aim is to contribute to the citizens forming their own well-founded opinions using the provided information.

Research projects

8.1. Workshop on various aspects of communication in the process of power grid expansion

In order to discuss the current knowledge from socio-scientific research among interested and professional members of the public, a workshop will be held at the beginning of the research period. The main topics are discourse approach, credibility, confidence, transparency and "lessons learned" from practical examples of power grid expansion so far.

8.2. Surveys to determine public concern

Representative and regular surveys provide a suitable basis for reacting to public concerns and needs with target-group-specific information and communication measures.

8.3. Investigation of the effect of on-site exposure measurements on the risk perception and the credibility of and the confidence in Länder authorities and grid operators

Which factors enhance credibility and confidence and which ones weaken them? What is the effect of on-site measurements carried out by Länder authorities and grid operators - are they considered useful? These questions are to be used to review the current strategy to inform the public.

8.4. Investigation of the role of authorities at events

The significance of the authorities' presence (lectures and attending panel discussions) at information events is determined. Ways of perceiving and processing information are to be researched. Approaches to improve the authorities' communication at events and to enhance confidence in authorities are determined.

8.5. Investigating the possibilities of local authorities (public health departments, medical officers and immission control authorities) as disseminators for risk communication in the process of power grid expansion

Staff members of various authorities (public health departments, especially medical officers and immission control authorities) are interviewed about their willingness and possibilities to act as disseminators for risk communication in the process of power grid expansion. In the interviews they are asked about their knowledge on radiation protection in the process of grid expansion. The results will show if additional information is also required with respect to the operational execution of events on risk communication. A tool for supporting the staff members and for conveying the necessary information (e.g. online training, sample presentations on video, FAQ, info brochures) is being developed. The necessary type of the tool and the method of its dissemination are to be determined as well. This tool will be tested, optimised and evaluated in cooperation with the target group.

8.6. Evaluation of risk communication measures

How does information have to be presented in order to be accessible and accepted by the residents living near high-voltage power lines? Is the available information presented in an appropriate and understandable form at the right place? Answering these questions contributes to shaping the provided information which allows citizens to form their own well-founded opinions.

8.7. Investigation of opinion formation

How does information have to be prepared in order to be accepted by target groups (in this case residents living near high-voltage power lines)? An analysis of exchanged opinions, of "believing", of "knowing" and of the willingness to exchange opinions and evaluations in the process of power grid expansion is being carried out.

State of 2017.09.16

© Bundesamt für Strahlenschutz