Occupational Exposure to Extremely Low‐Frequency Magnetic Fields and Risk of Amyotrophic Lateral Sclerosis: Results of a Feasibility Study for a Pooled Analysis of Original Data

Abstract

Previous meta-analyses have suggested an increased risk of amyotrophic lateral sclerosis (ALS) associated with occupational exposure to extremely low-frequency magnetic fields (ELF-MF). However, results should be interpreted with caution since studies were methodologically heterogeneous. Here, we assessed the feasibility of a pooling study to harmonize and re-analyze available original data. A systematic literature search was conducted. Published epidemiological studies were identified in PubMed and EMF-Portal from literature databases′ inception dates until January 2019. The characteristics of all studies were described, including exposure metrics, exposure categories, and confounders. A survey among the principal investigators (PI) was carried out to assess their willingness to provide their original data. The statistical power of a pooling study was evaluated. We identified 15 articles published between 1997 and 2019. Studies differed in terms of outcome, study population, exposure assessment, and exposure metrics. Most studies assessed ELF-MF as average magnetic flux density per working day; however, exposure categories varied widely. The pattern of adjustment for confounders was heterogeneous between studies, with age, sex, and socioeconomic status being most frequent. Eight PI expressed their willingness to provide original data. A relative risk of ≥1.14 for ALS and occupational exposure to ELF-MF can be detected with a power of more than 80% in a pooled study. The pooling of original data is recommended and could contribute to a better understanding of ELF-MF in the etiology of ALS based on a large database and reduced heterogeneity due to a standardized analysis protocol with harmonized exposure metrics and exposure categories.

Motor neuron disease risk and magnetic field exposures

“…What would be much more useful would be a pooled analysis of original data, enabling the harmonization of exposure assessments, exposure metrics, exposure categories and analytical techniques. Such an initiative is being attempted, although the task of harmonizing exposure assessments is far from trivial [ 11 ].…”

A Bibliometric and Scientometric Network Analysis of Occupational Safety and Health in the Electric Power Industry: Future Implication of Digital Pathways

“…Recent studies have also examined the effects of occupational exposure to extremely low-frequency magnetic fields [54][55][56]. These investigations have revealed potential adverse impacts on the nervous and cardiovascular systems.…”

Biological Effects of Magnetic Storms and ELF Magnetic Fields

“…The disadvantages of this approach are listed below. Firstly, most works use integral indicators of the induction and frequency values of the GMF during a magnetic storm [65][66][67]. Obtaining detailed amplitude-frequency characteristics will allow for the acquisition of additional information about the possible mechanisms of MF effects on biological functions [52].…”

“…Long-term exposure to an elevated ELF-MF f (50-60)b(>0.3)(GMF)t(years) among railway workers (drivers) appears to be a risk factor for developing amyotrophic lateral sclerosis [65].…”