Effects of microwave and radio frequency electromagnetic fields on lichens.
Urech, M, Eicher, B, Siegenthaler, J · 1996
View Original AbstractMicrowave radiation at 50 mW/cm² significantly reduced lichen growth by causing thermal damage and accelerated drying.
Plain English Summary
Swiss researchers exposed lichens (small organisms that grow on trees and rocks) to microwave radiation at 2.45 GHz for up to three years, using power levels similar to what you'd find near cell towers. They found that high-power microwave exposure (50 mW/cm²) significantly reduced the lichens' growth rate by causing them to heat up and dry out faster than normal.
Why This Matters
This study matters because lichens serve as biological indicators of environmental stress - they're like nature's canaries in the coal mine. The fact that microwave radiation at 50 mW/cm² caused measurable biological damage through heating effects demonstrates that even organisms we consider hardy can be affected by EMF exposure. While the researchers concluded the effects were primarily thermal, this doesn't diminish their significance. The 50 mW/cm² exposure level used in this study is well above typical environmental levels (which are usually measured in microwatts per square centimeter), but it's within the range you might encounter very close to high-powered transmitters. What this research reinforces is that biological systems respond to electromagnetic fields in measurable ways, and that thermal effects - often dismissed as 'safe' because they're understood - can still cause real biological harm.
Exposure Details
- Power Density
- 0.2, 5, and 50 µW/m²
- Source/Device
- 2.45 GHz
Exposure Context
This study used 0.2, 5, and 50 µW/m² for radio frequency:
- 20Mx above the Building Biology guideline of 0.1 μW/m²
- 333.3Kx 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
The effects of electromagnetic fields on lichens were investigated.
Field experiments of long duration (1-3 years) were combined with laboratory experiments and theoret...
Both species showed a substantially reduced growth rate at 50 mW/cm2. A differentiation between ther...
Theoretical estimates based on climatic data and literature showed that the growth reductions in the initial experiments could very likely have been caused by drying of the lichens from the heating with microwaves. The results of the other experiments support the hypothesis that the response of the lichens exposed to microwaves was mainly due to thermal effects and that there is a low probability of nonthermal effects.
Show BibTeX
@article{urech_1996_effects_of_microwave_and_1393,
author = {Urech and M and Eicher and B and Siegenthaler and J},
title = {Effects of microwave and radio frequency electromagnetic fields on lichens.},
year = {1996},
url = {https://pubmed.ncbi.nlm.nih.gov/8891192/},
}