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EFFECTS OF MICROWAVE IRRADIATION ON EMBRYONIC BRAIN TISSUE

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DAVID McK. RIOCH, M.D. · 1974

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A 1974 attempt to replicate microwave-stimulated rat fetal growth at 2450 MHz found no significant differences in fetal weight; only a final 1700 MHz experiment produced heavier fetuses.

Plain English Summary

Summary written for general audiences

This 1974 report describes an attempt to replicate earlier findings by Dr. Joseph C. Sharp and colleagues that low-dose 2450 MHz microwaves on day 13 of rat gestation stimulated fetal growth. Across rats of the Long-Evans, Fischer and Holtzman strains, exposures at 2450 MHz produced no significant differences in fetal weight or brain structure compared with controls. In a final experiment, Holtzman rats exposed at 1700 MHz had significantly heavier fetuses than controls.

Why This Matters

This 1974 Army-funded report describes an attempt to reproduce the earlier finding that low-dose 2450 MHz microwaves on day 13 of rat gestation stimulated fetal growth, with heavier fetuses and a larger cerebral cortex than in unirradiated rats. Across the replication experiments at 2450 MHz, no significant differences in fetal weight and no differences between irradiated and control brains were found. Only the final experiment, using 1700 MHz for one hour a day or overnight over several gestation days, produced significantly heavier fetuses (P < 0.005). The author notes that the original studies exposed rats in the late afternoon while all but the last group here were exposed earlier in the diurnal cycle, and asks whether a critical period in the circadian rhythm determines when radiation increases growth.

Finding

The average weight of the fetuses was larger and, in particular, the size of the cerebral cortex was greater than in rats similarly handled, but not irradiated.

In their words

“The average weight of the fetuses was larger and, in particular, the size of the cerebral cortex was greater than in rats similarly handled, but not irradiated.”
Cite This Study
DAVID McK. RIOCH, M.D. (1974). EFFECTS OF MICROWAVE IRRADIATION ON EMBRYONIC BRAIN TISSUE.
Show BibTeX
@article{effects_of_microwave_irradiation_on_embryonic_brain_tissue_g4840,
  author = {DAVID McK. RIOCH and M.D.},
  title = {EFFECTS OF MICROWAVE IRRADIATION ON EMBRYONIC BRAIN TISSUE},
  year = {1974},
  
  
}
No DOI on file for this study.

Quick Questions About This Study

No significant effect was found at 2450 MHz in this replication. Exposed and control fetuses did not differ significantly in weight at autopsy, and microscopic examination of the brains showed no differences between the groups.
The study did not reproduce it. Exposure at 2450 MHz and 20 mW/cm2 for 20 minutes produced no significant differences in fetal weight at autopsy on the 19th day of gestation in either Fischer or Holtzman albino rats.
In most experiments, fetuses of exposed rats did not differ significantly in weight or brain structure from controls. In the final experiment, rats exposed to 1700 MHz microwaves for one hour a day (10 to 15 mW/cm2) or overnight (5 to 7.5 mW/cm2) had significantly heavier fetuses (4.03 g and 4.23 g versus 3.73 g for controls, P < 0.005).
The final experiment found them. Holtzman albino rats were exposed at 1700 MHz in the Walter Reed chamber on gestation days 5 to 8 and 12 to 16, either for one hour a day or overnight for 14 to 16 hours, and were sacrificed on day 20. The brains of the control group were approximately 10% smaller than those of the exposed fetuses.
Dr. Joseph C. Sharp and colleagues had found that, in contrast with the destructive effects of ionizing radiation, low doses of microwaves (2450 MHz) on the 13th day of gestation stimulated growth in rat fetuses, with greater average weight and a larger cerebral cortex than in unirradiated rats. This report aimed to replicate those observations.