Biological responses to 30 mT static magnetic field in young and 36-month-old rats

Authors: Jovanovic M, Ille M, Vukovic A, Milovanovich ID, Mitic D, De Luka SR

Year: 2026 Jan 19

Category: Electromagnetic Biology

Journal: Electromagn Biol Med

DOI: 10.1080/15368378.2026.2617536

URL: https://pubmed.ncbi.nlm.nih.gov/41550064/

Abstract

Overview

This study aimed to investigate the effects of subchronic exposure to a 30 mT static magnetic field (SMF) on hematological parameters, as well as spleen and tibia cellularity, in both young and 36-month-old rats. Twenty-seven rats were divided into four groups: Young, Young SMF, Old, Old SMF. Two groups received SMF exposure for 10 weeks.

Findings

  • Blood Analysis: After exposure, blood counts, neutrophil-to-lymphocyte ratio (NLR), and platelet-to-lymphocyte ratio (PLR) were analyzed along with immune organ cellularity.
  • Effects on Lymphocytes and Platelets: SMF exposure decreased lymphocyte counts and increased NLR in both age groups. PLR rose only in young rats.
  • Age-dependent Effects: In 36-month-old rats, SMF exposure significantly lowered platelet counts, an effect not observed in young animals. The field increased tibial and splenic cellularity for both, but had opposite impacts on lymphocyte and erythrocyte proportions depending on age.
  • Immune Modulation: In young rats, SMF promoted a proinflammatory shift (increased NLR and PLR), while in older rats, SMF exposure acted as a nonspecific physiological stressor, likely triggering the General Adaptation Syndrome, leading to corticosterone-mediated immunosuppression and altered cell distribution.

Conclusion

This is the first study to demonstrate age-dependent, differential modulation of NLR and PLR by subchronic SMF exposure, indicating a proinflammatory risk in younger individuals and immunosuppressive effects in older ones. These results highlight the critical role of age in determining biological responses to static magnetic fields (SMFs) and stress the importance of age-specific evaluation in EMF safety assessments. There is a clear connection between EMF exposure and immune/inflammation changes, reflective of potential health risks.

Plain Language Summary

  • Method: Examined the impact of a 30 mT static magnetic field on blood and immune cells in very old (36-month-old) and young rats over 10 weeks.
  • Ethics: Humane treatment and anesthesia were employed.
  • Results: In old rats, SMF decreased platelet counts, potentially reducing blood clot risk, while also lowering lymphocytes and increasing NLR in both age groups. In young rats, PLR increased, indicating enhanced proinflammatory and clotting tendency.
  • Conclusion: The study confirms magnetic fields have age-dependent and potentially harmful biological effects—proinflammatory in the young and immunosuppressive in the old.
  • Recommendation: Future research and medical applications of magnetic fields must consider age due to differing health risks linked to EMF exposure.
static magnetic field age-dependent effects hematological parameters immune modulation inflammation rats EMF health risks
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