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Effects of exposure to microwaves on cellular immunity and placental steroids in pregnant rats.

Bioeffects Seen

Nakamura H, Seto T, Nagase H, Yoshida M, Dan S, Ogino K. · 1997

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Pregnant rats showed immune suppression from microwave exposure at levels that had no effect on non-pregnant rats, revealing pregnancy-specific EMF vulnerability.

Plain English Summary

Summary written for general audiences

Japanese researchers exposed pregnant and non-pregnant rats to microwave radiation at 2450 MHz (the same frequency used by microwave ovens and WiFi) for 90 minutes at 10 mW/cm². They found that pregnant rats showed significant immune system suppression, with reduced natural killer cell activity in the spleen, while non-pregnant rats showed no immune changes. The study reveals that pregnancy makes organisms more vulnerable to microwave radiation effects.

Why This Matters

This 1997 study provides important evidence that pregnancy creates heightened vulnerability to microwave radiation exposure. The 10 mW/cm² exposure level used here is significant because it falls within ranges that can occur near high-powered wireless devices or in occupational settings. What makes this research particularly concerning is the selective immune suppression seen only in pregnant subjects, suggesting that developing life faces unique risks from EMF exposure. The researchers found that microwaves activated stress response systems and altered hormone levels, with pregnant rats showing distinctly different biological responses than non-pregnant ones. This adds to a growing body of evidence suggesting that certain populations, including pregnant women and developing fetuses, may be more susceptible to EMF effects than current safety standards account for.

Exposure Details

Power Density
10 µW/m²
Source/Device
2450 MHz
Exposure Duration
90 minutes

Exposure Context

This study used 10 µW/m² for radio frequency:

Building Biology guidelines are practitioner-based limits from real-world assessments. BioInitiative Report recommendations are based on peer-reviewed science. Check Your Exposure to compare your own measurements.

Where This Falls on the Concern Scale

Study Exposure Level in ContextA logarithmic scale showing exposure levels relative to Building Biology concern thresholds and regulatory limits.Study Exposure Level in ContextThis study: 10 µW/m²Extreme Concern1,000 uW/m2FCC Limit10M uW/m2Effects observed in the Severe Concern range (Building Biology)FCC limit is 1,000,000x higher than this exposure level

Study Details

This study was designed to clarify the effect of exposure to microwaves during pregnancy on endocrine and immune functions.

Natural killer cell activity and natural killer cell subsets in the spleen were measured, as well as...

Skin temperature in virgin and pregnant rats increased immediately after exposure to microwaves. Alt...

Microwaves at the power of 10 mW/cm2 produced activation of the hypothalamic-pituitary-adrenal axis and increased oestradiol in both virgin and pregnant rats, suggesting that microwaves greatly stress pregnant organisms. These findings in pregnant rats suggest that--with exposure to microwaves--pregnancy induces immunosuppression, which could result in successful maintainance of pregnancy. This enhancement of adaptability to heat stress with pregnancy may be mediated by activation of placental progesterone and placental or pituitary beta-endorphin.

Cite This Study
Nakamura H, Seto T, Nagase H, Yoshida M, Dan S, Ogino K. (1997). Effects of exposure to microwaves on cellular immunity and placental steroids in pregnant rats. Occup Environ Med. 1997 Sep;54(9):676-80. doi: 10.1136/oem.54.9.676. PMID: 9423582; PMCID: PMC1128843.
Show BibTeX
@article{h_1997_effects_of_exposure_to_1074,
  author = {Nakamura H and Seto T and Nagase H and Yoshida M and Dan S and Ogino K.},
  title = {Effects of exposure to microwaves on cellular immunity and placental steroids in pregnant rats.},
  year = {1997},
  
  url = {https://pubmed.ncbi.nlm.nih.gov/9423582/},
}

Quick Questions About This Study

Japanese researchers exposed pregnant and non-pregnant rats to microwave radiation at 2450 MHz (the same frequency used by microwave ovens and WiFi) for 90 minutes at 10 mW/cm². They found that pregnant rats showed significant immune system suppression, with reduced natural killer cell activity in the spleen, while non-pregnant rats showed no immune changes. The study reveals that pregnancy makes organisms more vulnerable to microwave radiation effects.