Original article (in Slovenian) was published on 14/5/2025; Author: David Bajec
Boštjan Batagelj of the Faculty of Electrical Engineering explained that while wireless headphones and microwave ovens operate in the same frequency range, the radiation emitted by headphones is approximately 280,000 times weaker than that of a microwave oven.
The portal Sensa published an article on April 6 about electromagnetic radiation allegedly emitted by wireless headphones via Bluetooth. The article compared radiation levels from such headphones to those of microwave ovens, asserting that despite assurances of safety, research on wireless headphone safety suggests otherwise.
Boštjan Batagelj, professor at the Faculty of Electrical Engineering, University of Ljubljana and a member of its Laboratory for Radiation and Optics, told Razkrinkavanje.si that the level of electromagnetic radiation emitted by wireless headphones during daily use is not dangerous to humans according to current scientific findings. Although these headphones are used on the body, their radiation output remains below safety thresholds due to their low transmission power.
This is also demonstrated by the measured specific absorption rate (SAR), which quantifies the energy of electromagnetic radiation absorbed by the body, according to Batagelj.
The Jožef Stefan Institute emphasized that every technological standard is based on an extensive body of research, and device operating conditions are precisely defined for official measurements. For Bluetooth, key factors include the specific Bluetooth version, the orientation of the headphones, and the distance from the connected device.
They also shared a YouTube video which they explained illustrates why it is “impossible to provide a simple, definitive answer” to the question of how much radiofrequency radiation wireless headphones emit.
A study published in October 2016 by the Swiss Federal Office of Public Health found that the high-frequency radiation emitted by Bluetooth networks is “too weak to have an acute impact on health due to an increase in temperature following absorption”.
That study also referenced findings from the International Agency for Research on Cancer, specifically a working group of 30 scientists from 14 countries whose conclusions were published in the peer-reviewed journal The Lancet Oncology in July 2011.
The working group evaluated the carcinogenicity of radiofrequency electromagnetic fields. It reviewed research on mechanisms central to cancer development, including the effects of these electromagnetic fields on immune system function and gene and protein expression. It also examined studies on the potential effects of such electromagnetic fields on the blood-brain barrier and brain function.
Some of the reviewed studies confirmed an impact of radiofrequency electromagnetic fields on cancer development, but the group designated this evidence as weak. Based on research conducted on both humans and animals, the working group classified radiofrequency electromagnetic fields as “potentially carcinogenic to humans.”
The Swiss Federal Office of Public Health also cited a scientific paper on the effects of Bluetooth-generated electromagnetic fields on hearing. Conducted on young rats, the study found that four hours of daily exposure to Bluetooth signal at 2.4 GHz over a period of 40 days had no observable effect on the inner ear or auditory functions of the rats.
Additionally, the Office referenced a study investigating the effects of electromagnetic fields emitted by Bluetooth headphones and mobile phones on the human auditory nerve. This study found no short-term impact of Bluetooth on ear nerve structures.
According to a study published in June last year in the peer-reviewed journal Scientific Reports, long-term and frequent use of wireless headphones is associated with a higher risk of thyroid nodules – solid or fluid-filled lumps that form in the thyroid gland.
The authors of a study published in January last year in the peer-reviewed The Journal of International Advanced Otology examined the effects of microwave radiation at 2.45 GHz on the inner ear. They found that 12 juvenile rats exposed to this radiation experienced inner ear cell damage and heightened immune system activity. The authors noted that both factors can contribute to hearing impairment, but stressed that the clinical relevance of these findings for humans remains unclear, warranting further research.
The Jožef Stefan Institute clarified that wireless headphones emit with a power of 10 milliwatt. According to Article 2 of the Regulation on Electromagnetic Radiation in the Natural and Living Environment, radiation sources can include high-voltage transformers, power lines, transmitters, or other devices that impact the environment with electromagnetic radiation. The regulation distinguishes between low-frequency sources (0 Hz to 10 kHz with voltages above 1 kilovolt) and high-frequency sources (10 kHz to 300 GHz with power above 100 watts). This means that wireless headphones are not powerful enough to fall within the scope of this regulation.
Radiation protection levels are set based on the sensitivity of areas to the effects of electromagnetic fields. The first and strictest safety level applies to areas requiring increased protection, such as hospitals, schools, and residential zones. The second level applies to zones where higher radiation exposure is permitted, such as industrial and commercial areas.
Sensa also reported that wireless headphones “continuously emit radiofrequency radiation at 2.4 gigahertz, the same as microwave ovens.”
Batagelj confirmed that microwave ovens and wireless headphones emit in the same frequency range – microwaves at 2.45 GHz and Bluetooth headphones at 2.4 GHz. However, he emphasized that the key difference is in power: headphones have 280,000 times less power than a microwave oven.
The Jožef Stefan Institute likewise confirmed that although microwave ovens and Bluetooth devices operate at the same frequency (2.45 GHz), their signal power density differs significantly.
A typical microwave oven operates at 600 to 1200 watt, while wireless headphones emit around 10 milliwatt (0.01 watt), meaning 60,000 to 120,000 times less power than a microwave. This radiation level applies inside an active oven; outside, the power level is comparable to that of headphones.
Ana Vehovar, editor-in-chief of Sensa, stated in response to our queries that the article is a translation of a February post on Non-Toxic Dad, a blog. The original post referenced five scientific studies. In the first study, published in July 2021, researchers found increased risk of cardiomyopathy and tumours in male rats exposed to 900 MHz radiofrequency radiation.
The second study, published in May 2020, examined the impact of electromagnetic fields on children’s health. It found that children’s nervous systems are more sensitive to electromagnetic fields than those of adults.
A January 2023 review paper, based on a 2019 workshop, concluded that there is no reliable scientific evidence of harmful effects from low-intensity radiofrequency electromagnetic fields above 100 MHz on animals or plants in natural environments. Some physiological changes were observed in plants, but the results were too fragmented for definitive conclusions.
The authors of a December 2017 review paper found that exposure to electromagnetic fields can cause oxidative stress in various body tissues, potentially leading to cell damage, changes in enzyme activity, and imbalance in antioxidant defences.
In the final referenced review paper, published in August 2019, researchers summarized findings suggesting a link between radiofrequency radiation exposure and increased risk of developing brain or spinal cord tumours (schwannomas), fertility issues, and neurological changes, especially in children.
The claim that “despite regulatory assurances of safety, research shows otherwise” is categorized as falling into a grey area. Experts remain divided on the harmfulness of this kind of radiation, and studies supporting this claim were not conducted exclusively on humans. The claim is manipulative. As Batagelj explained, while Bluetooth headphones and microwave ovens operate in the same frequency range, the radiation output of headphones is 280,000 times weaker than that of a microwave oven. The Jožef Stefan Institute likewise confirmed that wireless headphones emit much weaker signals than microwave ovens.
