Are Bluetooth and Wi-Fi dangerous for our health?
Summary:
- Bluetooth and Wi-Fi are transmitted via electromagnetic waves around 2.4GHz, defined as microwave radiation.
- The potential danger of electromagnetic radiation depends on both its frequency and its strength.
- Studies indicate that very strong microwave radiation can cause damage to cells and may cause cancer at a low rate in animals. However, the results of these studies can not be transferred to realistic scenarios in humans, since Bluetooth and Wi-Fi signals are much lower in strength.
- There is currently no evidence for adverse health effects (like cancer) caused by Bluetooth, Wi-Fi, or mobile phone usage for humans.
Smartphones are everywhere. In fact, some estimates suggest that up to 81% of the global population may use one [1]. While the consequences of such a world-wide connectedness remain to be explored as time goes on, another question has already sparked a controversial debate: Are smartphones safe to use? Or, more specifically, is the electromagnetic radiation associated with smartphone use – such as Wi-Fi and Bluetooth – harmful?
In this article, we will look more closely at what scientific studies have found in this regard and discuss how we can interpret these results in the context of smartphone usage.
Tech gadgets like smartphones use several different technologies to communicate wirelessly with each other and with the internet. The most common of these, next to cellular networks like 4G and 5G, are Wi-Fi and Bluetooth. Both use electromagnetic radiation of the microwave range (around 2.4GHz) to exchange data.
In general, electromagnetic radiation can have many forms; from radio waves to light to x-and gamma-rays. To assess how dangerous electromagnetic radiation is, it is important to differentiate between its frequency and its strength. Frequency is proportional to the energy per wave. Therefore, lower frequency radiation like radio- and micro-waves are less dangerous than high-frequency radiation like x-rays. Radiation strength indicates how many waves per time are emitted and with that, how likely it is for damage to occur. Hence, the potential danger of electromagnetic radiation depends on both its frequency and its strength [2].
Bluetooth and Wi-Fi signals operate at frequencies that are considered safe, since they are lower than other harmless radiation such as light. However, just as one can get a sunburn from strong light sources, such as the midday sun, it is possible for strong microwave radiation to cause damage in cells and organisms [4-7]; after all, we can cook food using the extremely strong microwave radiation in microwave ovens. The question should, therefore, be: Do Bluetooth and Wi-Fi operate at strengths that are safe for humans?
Multiple different scientific studies have been performed to investigate this question over the last twenty years. To appropriately interpret their results, one has to distinguish between the different goals of the studies. Some studies aim to show that microwave radiation can, in principle, cause damage in cells and organisms, and therefore employ radiation strengths that well exceed the legal limits for commercial products [3] often paired with very long irradiation times. Doing so, it was indeed found that microwave radiation can cause damage to cells [4,5] and may cause cancer in mice [6,7]. However, as discussed before, such results cannot be used to assess the safety of wireless communication technologies. For that, scientists either devise low-radiation strength experiments on animals or large epidemiological studies on humans. To date, no study was able to rigorously show a causal link between commercially used microwave radiation and adverse health effects like cancer [8-10].
While this persuasively rules out high risks, many researchers point out that excluding low risks is more difficult, since epidemiological studies are less sensitive to more subtle effects due to their design [11]. Therefore, research on the topic continues and the World Health Organisation has classified some electromagnetic radiation as ‘possibly carcinogenic to humans’ in 2011 [12].
This may seem drastic given the low probability of a health risk, but it may be wise to err on the side of caution for now, since more than three quarters of the world population own a smartphone.
References:
- S. O’Dea, “Smartphone users worldwide 2016-2021”, statista, 2021
- Demtröder W. Experimentalphysik 2: Elektrizität und Optik. Springer. 2013
- Institute of Electrical and Electronics Engineers (IEEE). IEEE standard for safety levels with respect to human exposure to radio frequency electromagnetic fields, 3 kHz to 300 GHz. IEEE Std C95.1. 2005
- Deshmukh, PS et al. Detection of Low Level Microwave Radiation Induced Deoxyribonucleic Acid Damage Vis-à-vis Genotoxicity in Brain of Fischer Rats. Toxicology international. 20(1). 2013
- Durdik, M et al. Microwaves from mobile phone induce reactive oxygen species but not DNA damage, preleukemic fusion genes and apoptosis in hematopoietic stem/progenitor cells. Scientific Reports 9, 16182. 2019
- Capstick M, et al. Life-Time Dosimetric Assessment for Mice and Rats Exposed in Reverberation Chambers of the 2-Year NTP Cancer Bioassay Study on Cell Phone Radiation. IEEE Trans Electromagn Compat. 59(6):1798-1808. 2017
- Lin JC. Cancer Occurrences in Laboratory Rats From Exposure to RF and Microwave Radiation. IEEE Journal of Electromagnetics, RF and Microwaves in Medicine and Biology. 1(1):2-13. 2017
- Johansen C, et al. Cellular telephones and cancer–a nationwide cohort study in Denmark. J Natl Cancer Inst. 93(3):203-7. 2001
- Benson VS et al. The case of acoustic neuroma: comment on mobile phone use and risk of brain neoplasms and other cancers, International Journal of Epidemiology, 43(1):275. 2014
- INTERPHONE Study Group. Brain tumour risk in relation to mobile telephone use: results of the INTERPHONE international case-control study. Int J Epidemiol. 2010
- WHO TEAM Radiation and health. Radiation: Electromagnetic fields. WHO Q&A Detail. 2016
- WHO. IARC classifies radiofrequency electromagnetic waves as possibly carcinogenic to humans. Press Release No. 208. 2011