Responses of pulmonary intravascular macrophages to 915-MHz microwave radiation: ultrastructural and cytochemical study.
Singh B, Bate LA · 1996
View Original AbstractMicrowave radiation at 6.1 mW/cm² activated lung immune cells in pigs, while higher levels caused tissue damage.
Plain English Summary
Researchers exposed pigs to 915 MHz microwave radiation at two power levels for 24 hours and examined immune cells in their lungs called pulmonary intravascular macrophages. They found that lower-power microwave exposure activated these immune cells, while higher-power exposure actually damaged lung tissue. This suggests that even microwave levels intended for beneficial heating can trigger immune responses in the lungs.
Why This Matters
This study reveals a critical dose-response relationship in microwave radiation effects that challenges the assumption that non-thermal exposures are biologically inert. The finding that 6.1 mW/cm² activated immune cells while 11.4 mW/cm² caused tissue damage demonstrates that biological effects don't follow a simple linear pattern. What makes this particularly relevant is that these power densities are within ranges encountered from some wireless devices and industrial microwave applications. The activation of pulmonary macrophages at the lower exposure level is especially concerning because these cells play key roles in lung inflammation and immune responses. The researchers' conclusion that this activation could result from 'initiation of intracellular signaling' rather than just heating effects supports the growing body of evidence for non-thermal biological mechanisms of microwave radiation.
Exposure Details
- Power Density
- 6.1, 11.4 µW/m²
- Source/Device
- 915 MHz
- Exposure Duration
- 24h
Exposure Context
This study used 6.1, 11.4 µW/m² for radio frequency:
- 610Mx above the Building Biology guideline of 0.1 μW/m²
- 10.2Mx above the BioInitiative Report recommendation of 0.0006 μW/cm²
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 Details
Microwave (MW) radiation is being increasingly used as a source of heat supplementation during early postnatal development of pigs. Although MW radiation does not cause deleterious physiological effects, no specific information exists regarding its impact on immune cells such as macrophages. Pulmonary intravascular macrophages (PIMs) are emerging as important inflammatory cells due to their endocytic and secretory potential. An in vivo study was conducted to evaluate the effects of infrared, and low and high power MW radiation on the PIMs of pigs.
Pigs were exposed to infrared (IR), low MW (LMW; 6.1mW cm-2), and high MW (HMW; 11.4mW cm-2) radiati...
Ultrastructural and numerical data suggested enhanced secretory activity in the PIMs of LMW-treated ...
Elaboration of structural signs of secretory activity in the PIMs by LMW radiation in the absence of pulmonary pathological changes indicates its potential for cell activation in addition to the already established role of LMW in heat supplementation. This activation could be due to either increased core body temperature or initiation of intracellular signaling by the LMW radiation. This study also shows that the HMW radiation is capable of inducing pathology in the form of changes in the pulmonary interstitial matrix and may not be a good source of supplementary heat.
Show BibTeX
@article{b_1996_responses_of_pulmonary_intravascular_1328,
author = {Singh B and Bate LA},
title = {Responses of pulmonary intravascular macrophages to 915-MHz microwave radiation: ultrastructural and cytochemical study.},
year = {1996},
url = {https://pubmed.ncbi.nlm.nih.gov/8915456/},
}