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Neurodevelopmental anomalies of the hippocampus in rats exposed to weak intensity complex magnetic fields throughout gestation.

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Fournier NM, Mach QH, Whissell PD, Persinger MA. · 2012

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Rats exposed throughout gestation to a low-intensity complex magnetic field (30–50 nT) showed hippocampal structural anomalies and impaired fear learning as adults.

Plain English Summary

Summary written for general audiences

Pregnant Wistar rats were continuously exposed to one of four intensities of a complex magnetic field throughout gestation. Exposure to weaker or stronger intensities of the same field pattern did not interfere with hippocampal development or fear behavior.

Why This Matters

Effects appeared only within a narrow intensity window: only the low-intensity group (30–50 nT) showed both behavioral and structural changes. The researchers suggested that these alterations were subtle but permanent, with lasting effects on behavior.

Exposure Details

Magnetic Field
0.00002, 0.00005, 0.00058, 0.0012 mT
Source/Device
50 Hz
Exposure Duration
24 h/day during gestation (21 days)

Where This Falls on the Concern Scale

Study Exposure Level in ContextStudy Exposure Level in ContextThis study: 0.00002, 0.00005, 0.00058, 0.0012 mTExtreme Concern - 5 mGFCC Limit - 2,000 mGEffects observed in the Slight Concern range (Building Biology)FCC limit is 10,000 times higher than this level
A logarithmic frequency spectrum from 10 Hz to 100 GHz showing where this study's 50 Hz exposure sits relative to common EMF sources.Where This Frequency Sits on the EMF SpectrumELFVLFLF / MFHF / VHFUHFSHFmm10 Hz100 GHzThis study: 50 HzCell phones~1 GHzWiFi2.4 GHz5G mm28 GHzLogarithmic scale

Study Details

To investigate the effect of weak intensity magnetic fields on the prenatal brain, pregnant Wistar rats were continuously exposed to one of four intensities (reference: 5–20 nT; low 30–50 nT; medium 90–580 nT; high 590–1200 nT) of a complex magnetic field sequence designed to interfere with brain development.

As adults, rats exposed to the low-intensity (30–50 nT) complex magnetic field displayed impairments...

These findings suggest that prenatal exposure to complex magnetic fields of a narrow intensity window during development can result in subtle but permanent alterations in hippocampal microstructure and function that can have lasting effects on behavior.

Cite This Study
Fournier NM, Mach QH, Whissell PD, Persinger MA. (2012). Neurodevelopmental anomalies of the hippocampus in rats exposed to weak intensity complex magnetic fields throughout gestation. Int J Dev Neurosci. 2012 Oct;30(6):427-433.
Show BibTeX
@article{nm_2012_neurodevelopmental_anomalies_of_the_249,
  author = {Fournier NM and Mach QH and Whissell PD and Persinger MA. },
  title = {Neurodevelopmental anomalies of the hippocampus in rats exposed to weak intensity complex magnetic fields throughout gestation.},
  year = {2012},
  
  url = {https://www.sciencedirect.com/science/article/abs/pii/S0736574812004364},
}

Quick Questions About This Study

Only the low-intensity group (30–50 nT) showed hippocampal anomalies; weaker and stronger intensities did not.
Rats in the low-intensity exposure group displayed impairments in contextual fear learning.
Low-intensity exposures resulted in a reduction in overall hippocampal size and promoted subtle dysgenesis of the CA1 and CA3 regions.
The researchers suggested the alterations were subtle but permanent, with lasting effects on behavior.