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

Objective

Since the publication of the meta-analysis on occupational exposure to magnetic fields and neurodegenerative diseases by Vergara et al. (2013), there have been several new publications. The planned literature study should provide a summarised risk assessment of all the studies that are now available.

Assessment of the current data situation for the meta-analysis

The current state of the evidence is briefly summarised below. A scientific opinion can be found in the article Do low-frequency magnetic fields cause diseases of the nervous system? (only available as a German version).

1. Amyotrophic lateral sclerosis (ALS)

Three new meta-analyses reported a correlation between occupational exposure to low-frequency magnetic fields and an increased risk of ALS (Huss et al. 2018; Gunnarsson und Bodin 2019; Jalilian et al. 2020). These findings are consistent with the older meta-analysis by Vergara et al. (2013). The only meta-analysis on domestic exposure to low-frequency magnetic fields and an increased risk of ALS conducted to date provided no evidence of such a correlation (Röösli 2018). A pooled study on magnetic field exposure and ALS was tendered in a separate research project (“1.2 Pooled analysis on ALS and exposure to magnetic fields”).

2. Alzheimer’s dementia

Three new meta-analyses report a correlation between occupational exposure to magnetic fields and an increased risk of developing Alzheimer’s dementia (Jalilian et al. 2018; Gunnarsson und Bodin 2019). The new results confirm findings from the meta-analysis by Vergara et al. (2013). There are currently only two studies on domestic exposure. A meta-analysis is therefore not yet feasible.

3. Other neurodegenerative diseases

A new meta-analysis found no evidence of an increased risk of Parkinson’s dementia in connection with exposure to magnetic fields (Gunnarsson und Bodin 2019). This is consistent with the older meta-analysis by Vergara et al. (2013). For other diseases (e.g. multiple sclerosis or other types of dementia), no renewed meta-analysis was carried out. In the meta-analysis by Vergara et al. (2013), no risk increase was shown for occupational exposure to magnetic fields. The study situation on these diseases and a potential correlation with exposure to magnetic fields does not yet allow for a meta-analysis.

Summary

• The newly published meta-analyses (2018–2020) bring the evidence up to date. Therefore, no gain in knowledge is to be expected from a renewed meta-analysis. The project has therefore been cancelled.
• However, the evidence reported in the new meta-analyses for increased risks of ALS and Alzheimer's dementia in connection with occupational exposure to magnetic fields has limited informative value. There was evidence of publication bias (Gunnarsson und Bodin 2019; Jalilian et al. 2020). Possible misclassification of exposure and confounding were also identified as reasons for a possible systematic bias of the results (Jalilian et al. 2018; Huss et al. 2018).
• Within the framework of the research programme "Radiation protection in power grid expansion", a parallel project was started to investigate Associations between ALS and exposure to magnetic fields. In this project, a joint analysis of high-quality epidemiological studies should reduce scientific uncertainties. The study will be announced shortly.

Literature

Gunnarsson, L.-G. and L. Bodin (2019). "Occupational Exposures and Neurodegenerative Diseases—A Systematic Literature Review and Meta-Analyses." Int J Environ Res Public Health 16(3): 337.

Huss, A., et al. (2018). "Occupational exposure to extremely low-frequency magnetic fields and the risk of ALS: A systematic review and meta-analysis." Bioelectromagnetics 39(2): 156-163.

Jalilian, H., et al. (2018). "Occupational exposure to extremely low frequency magnetic fields and risk of Alzheimer disease: A systematic review and meta-analysis." Neurotoxicology 69: 242-252.

Jalilian H., et al. (2020). "Amyotrophic lateral sclerosis, occupational exposure to extremely low frequency magnetic fields and electric shocks: a systematic review and meta-analysis." Rev Environ Health: 36(1): 129–142.

Röösli, M. and H. Jalilian (2018). "A meta-analysis on residential exposure to magnetic fields and the risk of amyotrophic lateral sclerosis." Rev Environ Health 33(3): 309–313.

Vergara, X., et al. (2013). "Occupational exposure to extremely low-frequency magnetic fields and neurodegenerative disease: a meta-analysis." J Occup Environ Med 55(2): 135-146.