SSM perspective
Background
The Swedish Radiation Safety Authority’s (SSM) Scientific 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 Scientific Council agree with the complete report. This increases the strength of the given conclusions.
Objective
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 put this in the context of present knowledge. The report gives the Swedish Radiation Safety Authority an overview and provides an important basis for risk assessment.
Results
The present report is number fourteenth in a series and covers studies published from April 2018 up to and including December 2018 (previous report covered studies published up to and including Mars 2018). 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.
Overall, the age standardised incidence of brain tumours does not give support to any causal relationship with radio wave exposure from mobile phone use. If there is an impact, it appears to be so weak that it cannot be detected in incidence trend studies.
Studies on impact on cognitive functions and behaviour of children and adolescents often report associations with the use of wireless information technology. Since the strongest associations have been found correlated to applications which give low exposure to the head, e.g. texting, it seems clear that other reasons than radio wave exposure primarily causes the association. A few attempts have been done in order to discriminate radio wave exposure from other possible sources of impact. In such a study some indications of weak impact of radio wave exposure was found but this observation needs to be confirmed in similar study approaches before any robust conclusions can be drawn.
In line with previous reports the council report studies on increased oxidative stress due to weak radio wave exposure in animal studies, some even below the reference levels. Increased oxidative stress was observed in the eye, testes and sciatic nerve. However, several studies did not observe oxidative stress in the brain. 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.
Some animal studies observed that radio wave exposure of testes resulted in decreased sperm counts, sperm viability and serum testosterone. To what extent such exposure can also affect humans need to be investigated. A meta-analysis study concluded a slight increased risk for ALS among workers with increased exposure for low frequency magnetic fields. 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.
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 1 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.
The Swedish authorities' recommendation to generally limit exposure to low frequency magnetic fields, due to the observed increased incidence of childhood leukaemia close to power lines, still remains.
Need for further research
Despite the fact that no health risks with weak electromagnetic fields have been established today, the Authority considers that further research is important, in particular regarding long-term effects as 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 and to what extent it may affect human health.
There is also a need to further investigate the observed decreased sperm counts, sperm viability and decreased serum testosterone due to radio wave exposure of testes in animal studies before any conclusions concerning the possible implications for human health can be drawn.
Since many studies report impact on cognitive functions due to the use of information technology, it is desirable to further investigate if this association to some extent depend on the resulted radio wave exposure. To be able to draw reliable conclusions on this issue, it is important to further develop and apply methods that have the ability to clearly discriminate between different causal relationships.
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 encourage researchers to start undertaking epidemiological studies, i.e. cohort studies, in this area.
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 transfer technology, wireless energy transmission 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, therefore there is a special need for research.
Another vital issue to investigate is whether low frequency magnetic fields contribute to the increased incidence of childhood leukaemia that has been observed close to power lines in epidemiological studies.
It is also desirable to investigate different health effects based on combinations between electromagnetic fields and other factors, both physical factors and chemical factors.
There is also a need to better clarify the origin for the different problems MRI-exposed workers have experienced described in previous council reports.