𝕋 here has been a lot of fear lingering as a result of the COVID-19 epidemic.  The lines of masked shoppers waiting at grocery stores whispers in apocalyptic tones.  Some of these anxieties have bled over into health concerns over the roll-out of 5G, the next generation cell-phone system.  Confusion about the word “radiation” has led to certain municipalities banning the rollout despite the fact that this system is less-penetrating, and less energetic than its predecessors. This is why you will be seeing more overall numbers of 5G antennae than in older versions of cellular infrastructure. Accordingly, 5G very well may prove much safer than previous incarnations despite its expanding prevalence.

Radiation, in general, can cause harm in three ways.  First and most deadly, certain radiation can ionize atoms, but this only occurs due to extremely high frequency light such as gamma and x-ray waves.  Gamma waves are billions of times higher frequency, and far, far more energetic than the gigahertz frequencies used in modern cell phones.  The second means by which we may be affected is through heat.  Certain wavelengths of stimulation, like the microwaves in 5G can resonate with water and raise their temperature.  Fortunately, governments worldwide are keen on this effect and have unanimously limited the power of signals so as to never raise the surface temperature of the skin by greater than 1 degree C.  Beyond water heating, radiation can variably stimulate conductive materials, electrically.  At least one high-profile academic has reasoned that EMR can affect voltage gated calcium channels in the body.

Humans, however, are thousands of times less conductive than a copper wire.  This means we are less electrically susceptible to the induction of a current.  The skin is by far the least conductive part of the human body and it is this barrier that is likely to interact most directly with cellular radiation. In fact, the skin is such a powerful deflector of radiation that less than 10% of the incident 5G radiation from emissions at the surface makes it past the dermis and epidermis.  The penetration is much more severe for the soon-to-be displaced technologies such as 4G.  Considering that 5G operates at higher frequencies than older tech, between 24 and 72GHz, ponder the following chart from NYU:

The authors indicate that the new cellular technology is much less penetrating into human skin than its predecessors.  They make use of the long-known engineering relations for skin depth penetration, δ, indicating how radiation in this frequency range depends primarily upon three parameters of the incident body:  

δ=√(2ρ/ωμ)

ρ scales how resistant we are to conducting current in Ohm*meters.  It is, unsurprisingly, quite substantial for a human.  Magnetic permeability, 𝜇, is resistance to establishment of a magnetic field.   𝜇 is 0 for a vacuum and up to 0.25H/m for iron but on the order of 10⁻⁶ H/m for water.  So while the ratio ρ/μ alone confers radiation penetration depth to the human body, it is the frequency contribution, ω, to the denominator of this equation that minimizes tissue penetration at higher and higher GHz bands.

I do not mean to suggest that exposure to cellphone radiation has no effect on life.  Let me be clear that radiation is an energetic transaction between atoms.  Clearly, when the sun comes up in the morning, we are stimulated to awaken.  There is ample evidence that the frequency of that visible radiation is in large part responsible for regulating alertness and may impact immune health.  No serious investigator believes that radiation, in general, is completely innocuous and so international consortiums have gone to great length to limit exposure from cell phones.  Radiation pollution is not something we should treat casually, and we should constantly re-evaluate the parameters of our analyses.  Many towns have taken on light pollution in the past, and one might consider cellular radiation as a related but highly intrusive version.

What are the potential dangers of cellular radiation?

Dozens of research groups have tried to pin down any direct negative consequences of cellular radio wave exposure but in the words on one gargantuan metanalysis, “no consistent relationship between power density, exposure duration, or frequency, and exposure effects” was apparent across 98 different studies examined.  Childhood leukemia has been linked to proximity to power lines but no etiological mechanism has been been apprehended and so the cause is not clear. For instance, individuals living directly under power lines might be correlated under various socio-economic guises as well.

Alternatively, the greatest danger of ubiquitous cellphone radiation may concern our ecosystem rather than damage to our own bodies, directly. Since we humans do not exist without our biosphere, this is not a small issue. While cellular radiation fails to penetrate very deep into our bodies, it might affect lifeforms with a large surface area and small volume.  Galileo’s square-cube law makes it plain that the smaller an organism gets, the more this becomes a problem, so I am concerned about small bugs and bacteria.  Plants also have leaves which constitute a tremendous surface relative to volume and so it is unclear how this radiation will affect their health.

At the end of the day, we must compare risk versus benefit in any technology. For 5G and previous generation cell phones we find that they are both, by every available measure far, far less deadly than your car, the likes of which kill 35,000 people a year in the U.S.  It is estimated that 100,000 more die from the air pollution resulting from automobile combustion.  That degree of threat is in no way apparent to any scientists studying cellphone radiation in the context of human health.  

Even on its own scale, next gen 5G tech is exponentially less scary than its predecessors since overall power density exposure remains restricted identically to 4G while 5G penetrates much less within our bodies. More time is needed to gather information and retrospectively examine cellular radiation pollution effects in general, yet it does not appear that the new advances are doing anything other than paring back long-established risks. As is so often the case, fears over 5G seem to reflect our desire to externalize blame onto technology instead of taking responsibility for our own usage behaviors.