Numerical dosimetry of specific absorption rate of insects exposed to far-field radiofrequency electromagnetic fields

Abstract

Overview

This study investigates the exposure of adult insects—including ladybugs, honey bee workers, wasps, and mantises—to far-field radiofrequency electromagnetic fields (RF-EMF) over a frequency range of 2.5 to 100 GHz. The main goal was to estimate the specific absorption rate (SAR) in insect tissues, with particular focus on the brain, in order to predict biological effects caused by EMF energy absorption.

Methods

• Numerical dosimetry performed using the finite-difference time-domain (FDTD) method.
• Insects modeled as 3-tissue heterogeneous dielectric objects: cuticle, inner tissue, and brain tissue.
• EMF source modeled as sinusoidal plane waves at single frequencies in a far-field scenario.

Findings

• Whole-body averaged, tissue-averaged, and 1 milligram SAR values were determined for insects at all examined frequencies for 10 different incident plane waves.
• SAR values were normalized to an incident power density of 1 mW/cm².
• Maximal EMF absorption in inner and brain tissues was observed at 6, 12, and 25 GHz, except the ladybug's brain (max at 60 GHz).
• Peak 1 mg SAR values: honeybee (39.2 W/kg), wasp (169.2 W/kg) when E-field was aligned along body length.
• Maximal brain SAR values (W/kg) for incident power density of 1 mW/cm²: honeybee 3.6 (25 GHz), wasp 5.4 (12 GHz), mantis 5.2 (25 GHz), ladybug 10 (60 GHz).
• Maximal inner tissue absorption (W/kg) at 1 mW/cm²: honey bee 4.3 (12 GHz), wasp 5.9 (12 GHz), ladybug 4.8 (12 GHz), mantis 3.3 (6 GHz).
• Cuticle absorption increased with frequency; ladybug cuticle SAR was 0.1 W/kg at 2.5 GHz and 11.9 W/kg at 100 GHz.

Conclusion

• This is the first estimation of SAR for various insects using three-tissue 3D insect models across a wide RF frequency spectrum.
• SAR values in insects depended on frequency, polarization, direction, and morphology.
• The research highlights the potential risks of EMF exposure to insects—which is relevant for 5G safety and environmental policymaking—and provides a basis for future recommendations regarding safe frequencies and doses for RF-EMF exposure in the studied organisms.
• Future studies are needed to include new insect models, thermal simulations, and broader assessments of EMF impact.