Expert discussion of the mechanisms of action of electric, magnetic, and electromagnetic fields on biological systems – from molecular dynamics simulations to experiments

What is the issue?

In most countries, the population is now almost continuously exposed to human-made electromagnetic fields. The aim of ongoing research is to determine whether weak magnetic fields (below regulatory limits) can trigger biologically relevant effects with potential health implications. An initial step toward understanding health effects is identifying the physical interactions of electric, magnetic, and electromagnetic fields (EMF) with parts of the human or animal body. These structures vary in size ranging from tissues (e.g. the skin) to individual cells and proteins to the spins of unpaired electrons in molecules (radicals)***. During the expert discussion, internationally recognised specialists in dosimetry, biology, and theoretical biophysics examined the current state of research and open questions.

What is the current situation?

For decades, studies have investigated the relationship between weak magnetic fields (below existing international limit value recommendations) and possible health-relevant effects. Epidemiological and experimental studies have occasionally indicated this possibility. Mechanisms for explaining such effects have not yet been established.

Various biophysical effects have been studied for years. Some have recently become the focus of research because of new findings. These include:

• the radical pair mechanism (external magnetic fields influence chemical reactions involving molecules with unpaired electrons)
• protein misfolding (the development of large molecules into a stable state that does not correspond to the natural state)
• the response of neural networks (nerve cells connected in networks) to external fields

What were the objectives of the expert discussion?

The expert discussion served as an exchange between experts from fields covering the full spectrum – from molecules to humans. Beyond assessing the current state of research, the expert meeting focused on identifying open questions and fostering interdisciplinary discussion. Special attention was paid to the following points:

• What are the biophysical mechanisms of action that are currently most discussed and not clarified and that could be relevant to health?
• What theoretical and experimental methods are currently used for their research?
• What role does computing with supercomputers play in the study of the mechanisms of action?

More than 50 experts (including 22 who attended in person) from seven countries (Germany, Austria, France, Great Britain, Finland, Italy, and Japan) participated in the hybrid expert discussion.

What results did the research discussion provide?

Because of the effects on different scales (organs, individual cells, proteins), the results are summarised into three thematic areas: effects at the atomic or subatomic level (quantum effects), effects on protein folding, and effects on biological tissues.

Effects at the atomic or subatomic level (quantum effects)

Researchers now understand the radical pair mechanism relatively well compared with other possible non-thermal interactions of magnetic fields and biological systems. This is due mainly to studies on the sense of orientation of different animal species.

The interactions (fluctuations) between spin systems occurring in radical pairs move back and forth between two characteristic states: the singlet state and the triplet state. An external magnetic field (e.g. the Earth’s magnetic field) can influence the fluctuation rates that occur and thus chemical reactions, the final products of which depend on the spin state of the radicals involved. In studying the radical pair mechanism, combined quantum mechanics and molecular dynamics simulations provide insights into reaction processes that are inaccessible through experiments. This is why the term “computer-aided microscope” is often used. Previous simulations show relatively short radical lifetimes, which do not fully explain the sensitivity to magnetic fields observed in migratory birds. Known radical pair reactions in animals require light and specific light receptors that humans lack. So far, no chemical processes are known in humans in which the radical pair mechanism could play a role. However, further research is being carried out on this subject.

Effect on protein folding

In general, the effect of weak EMF on large molecules such as proteins is extremely low compared with the usual molecular motion at ambient temperature (Brownian molecular motion). The integration of magnetic fields in simulation studies requires further research. An open question is how magnetic fields influence molecular transport processes and whether parts of molecules can bind other molecules. A major challenge is that atomic-level simulations can only calculate the smallest fractions of a second, whereas biological processes occur over several seconds.

Effect on biological tissue

In order to determine the size of EMF generated in biological tissue, computer-aided methods are used, particularly at low EMF frequencies (below 1 MHz). This requires an improvement in the data situation regarding the dielectric properties of tissues. Using imaging techniques such as magnetic resonance imaging, researchers can create highly detailed body models to realistically simulate threshold currents responsible for the generation of phosphenes (flickering light phenomena at the edge of the field of view at high field strengths). There is still an open question regarding the microscopic scale at which conductivity and permeability can still be considered macroscopic variables: Is it at the level of the mitochondrion (the powerhouse of the cell) or the entire cell?