Effects of Extremely Low-Frequency (50/60 Hz) Electromagnetic Field Exposure on Oxidative Stress Biomarkers in Rodent Models: A Systematic Review and Meta-analysis

Extremely low-frequency electromagnetic fields at the 50/60 Hz mains frequency are ubiquitous and classified by the International Agency for Research on Cancer as possibly carcinogenic to humans. Altered redox balance is the most frequently proposed mechanism, yet rodent findings are inconsistent and have not been quantitatively synthesised. Following PRISMA 2020, PubMed and Scopus were searched for controlled studies in rats or mice exposed to 50/60 Hz fields and reporting oxidative stress biomarkers. Risk of bias (SYRCLE) and certainty of evidence (GRADE, adapted for animal studies) were assessed, and Hedges’ g was pooled using random-effects models. Eight rat studies (1–7000 μT) yielded 48 non-independent effect estimates across seven biomarkers. Exposure increased malondialdehyde (SMD 2.84; 95% CI 1.70–3.98), total oxidant status (1.33; 0.50–2.17), total thiol molecules (1.27; 0.25–2.29), and total antioxidant status (1.25; 0.72–1.78), whereas superoxide dismutase and catalase were unchanged. Heterogeneity was substantial (I 2 52–82%), four biomarkers derived from a single laboratory, and certainty was very low throughout. Findings suggest a shift toward oxidative stress, with greater lipid peroxidation and oxidant burden alongside higher non-enzymatic antioxidant capacity; direction is better supported than magnitude. Most exposures exceeded ICNIRP public reference levels, so results reflect laboratory conditions rather than human risk.