SSM perspective
Background
The Swedish Radiation Safety Authority’s (SSM) Scientifc Council on Electromagnetic Fields monitors current research on potential health risks in relation to exposure to electromagnetic fields and provides the authority with advice on assessing possible health risks. The Council gives guidance when the authority must give an opinion on policy matters when scientific testing is necessary. The council is required to submit a written report each year on the current research and knowledge situation.
This is a consensus report. This means that all members of the Scientifc Council agree with the complete report. This increases the strength of the given conclusions.
Objectives
The report has the primary objective of covering the previous year’s research in the area of electromagnetic fields (EMF) and health but also to place this in the context of present knowledge. The report gives the authority an overview and provides an important basis for risk assessment.
Results
The present report is number fifteen in the series and covers studies published from January 2019 up to and including December 2019. The report covers different areas of EMF (static, low frequency, intermediate, and radio frequency fields) and different types of studies such as biological, human and epidemiological studies.
No new established causal relationships between EMF exposure and health risks have been identified.
New research on brain tumours and mobile phone use is in line with previous research suggesting mostly an absence of risk. The thyroid gland is potentially highly exposed during mobile phone calls but little research on thyroid cancer has been conducted so far. However, some suggestive elevated incidence of thyroid micro-carcinoma associated with long-term and more frequent mobile phone use have been observed. Recall bias of self-reported mobile phone use may be an alternative explanation for these results.
Associations between mobile phone use and non-specific symptoms such as headache, and mental health problems have been observed in epidemiological studies. However, several studies suggest that these associations may be attributed to other factors such as short sleep duration or stress. One factor that contradicts that radio wave exposure is a significant contributing element is that stronger correlations are often seen when the exposure level is expected to have been low.
The studies published in 2019 support that RF exposure does not change the concentration of biomarkers in human beings with symptoms attributed to electro hypersensitivity. However, the sample sizes of the studies were small, thereby limiting the statistical power to show absence of a risk with satisfactory certainty.
In line with previous reports, the animal study section reports observed increased oxidative stress due to weak radio wave exposure, some even below the reference levels. Oxidative stress is a natural biological process that can sometimes be involved in pathogenesis, but under what circumstances oxidative stress due to weak radio wave exposure may affect human health remains to be investigated.
As previous years, there are reports of observed effects on behavior and spermatozoa (without an effect on male fertility, however) in animal studies. However, there is not much consistency between the studies.
Despite the increasing use of applications in the intermediate frequency (IF) range of the electromagnetic spectrum (300 Hz-10 MHz), scientific evaluation of potential health risks in that range is scarce. However, the few studies identified by the council in this area have not indicated any health effects below current reference levels.
The annual report also includes a section where studies that lack satisfactory quality have been listed. This year, as well as last year, many studies have been excluded due to poor quality. From a scientific perspective, studies of poor quality are irrelevant. They are also a waste of money, human resources and, in many cases, experimental animals.
Relevance
The results of the research review give no reason to change any reference levels or recommendations in the field. However, the observations of biological effects in animals due to weak radio wave exposure clearly show the importance of maintaining the Swedish Environmental code precautionary thinking.
The hands-free recommendation for mobile phone calls remains even though trends of glioma incidences do not provide support for an increasing risk caused by mobile phone radio wave exposure. However, observed biological effects and uncertainties regarding possible longterm effects justify caution.
No new findings that clearly change the suspicion of a causal link between weak low-frequency magnetic fields and childhood leukemia have emerged in the report. The authorities recommendation to generally limit exposure to low frequency magnetic fields therefore still remains. It is the Swedish Environmental code1 that applies when there is a need to assess precautionary measures in the area.
Need for further research
Despite the fact that no health risks associated with weak electromagnetic fields have been demonstrated up to date, the authority considers that further research is important, in particular regarding long-term effects as more or less the entire population is exposed. One key issue here is to further investigate the relationship between radio wave exposure and oxidative stress observed in animal studies and to establish whether a relationship in humans exists and, if so, to what extent it may affect human health.
The incidence time trends for thyroid cancer are increasing. There could be numerous different reasons for this. However, the newer mobile phone generations can potentially give relatively high radio wave exposure to the thyroid gland and therefore it is desirable to closely examine a possible causal relationship. So far, the research regarding this issue has been limited.
There is also a need to further investigate the observed effects on behavior and spermatozoa observed in animal studies. Since consistency between the studies are lacking, it is important to emphasize that the next step here should be to develop high quality study designs. This step is necessary before these observations can contribute to the overall picture of knowledge.
Since epidemiological studies often report impact on cognitive functions, non-specific symptoms such as headache and mental health problems due to the use of information technology, it is desirable to further investigate if this association to some extent depends on the resulting radio wave exposure. The authority would like to emphasize that innovative approaches allowing differentiating between device usage and physical radio frequency EMF exposure are needed to better understand the causality of radio frequency EMF exposure for health.
Wireless information technology is constantly evolving and new frequency ranges will be used. The fifth generation mobile telecommunication system (5G) will be installed all over the world within the next few years. Even though there is no established mechanism for affecting health from weak radio wave exposure, there is need for more research covering the novel frequency domains used for 5G. The authority also encourages researchers to start undertaking epidemiological studies, i.e. cohort studies, in this area. Only about 100 in vivo and in vitro studies are available that have considered exposures to frequencies higher than about 6 GHz. There are currently very few studies in the 26 GHz band.
New technologies for inductive wireless energy transfer based on intermediate frequency magnetic fields will probably be implemented for many different applications in the near future. In contrast to wireless information communication technology, wireless energy transfer in principle always results in relatively strong local fields. This makes it very important to obtain a robust basis for risk assessment of such fields. Today, there is a lack of studies in this frequency domain, and therefore, there is a special need for research in this area.
Another vital issue to further investigate is whether exposure to low frequency magnetic fields contribute to the slightly increased incidence of childhood leukemia that has been observed close to power lines in epidemiological studies. When animal studies are planned regarding this issue, the authority encourage the use of the novel mouse design ETV6-RUNX1 (Campos-Sanchez et al. (2019)).
It is also desirable to investigate different health effects based on combinations of electromagnetic fields and other factors, both physical factors and chemical factors.