Abstract

Overview

This study discusses the occupational exposure to extremely low-frequency magnetic fields (ELF-MF) and its association with an increased risk of amyotrophic lateral sclerosis (ALS). The aim was to evaluate the feasibility of pooling original data for a more harmonized and robust analysis.

Findings

• A systematic literature search was conducted to locate studies from databases' inception until January 2019.
• Characteristics such as exposure metrics, categories, and potential confounders were described.
• 15 articles ranging from 1997 to 2019 were reviewed, showing methodological diversity.
• Most studies measured ELF-MF as average magnetic flux density per working day.
• Considerable variation in exposure categories and confounder adjustments were noted among the studies.
• A survey among principal investigators showed eight were willing to share their original data.
• Analyzed pooled data could detect a relative risk of ≥1.14 for ALS at over 80% power.

Conclusion

The pooling of original data is strongly recommended to improve understanding of ELF-MF's role in ALS etiology. Standardizing analysis protocols and harmonizing exposure metrics can substantially reduce heterogeneity and enhance study accuracy.