Is Small Cell Antenna Radiation Harmful?

A recent half-day symposium at the Commonwealth Club in San Francisco was titled “Humanity at a Crossroads: New Insights Into Technology Risks for Humans and the Planet.” It was sponsored by 14 organizations with names such as the American Academy of Environmental Medicine and the California Brain Tumor Association. Every speaker had strong credentials and powerful arguments from serious research. It focused on the likely outcomes of our increased production of electromagnetic radiation (EMR) from ever more pervasive mobile telecommunications systems. One speaker compared beam-forming from an antenna to lasers, as if antennas that formed beams were Death Stars concentrating so much power on one spot that planets disappeared (he did not suggest this image directly, more with his hand and tone, but he did say “lasers” which, if used to send light down a piece of glass in a fiber optics network, emits no radiation at all). By the end of the day the parade of alarm bells was deafening.

Should we take this sort of talk about radiation seriously, or is this another case of “outlier science,” such as those who deny human contribution to global warming by cherry picking selected studies and analyses (or something in between)? Over 700 billion smart phones have been sold over the last decade. We are surrounded by other radiating devices at similar frequencies—WiFi routers, Bluetooth connections, cordless telephones, television remotes, video baby monitors, over-the-air television, military communications, radar, the sun. Some lower frequency sources, such as power lines and AM and FM radio, have been with us for a very long time, power lines more than a century. Yet we are not all rushing to the cancer ward. Of the many epidemiological studies attempting to assess actual increases in cancer and other harms that could be correlated to radical increases in cell phone use, only one shows any possible effect (it is from Sweden), and critics on both sides admit these studies are suggestive at best. However, we are not scientists doing research on the biological effects of radiation. We have limited capacities to evaluate the relative merits of serious radiation research beyond recognizing that more than 25,000 studies have been published with substantially inconsistent results, few have established cause and effect (most are correlations), many of the positive results (that there are problems) either cannot be reproduced or sit so close to the margin of statistical error as to question their relevance if not their results, and none come from testing human beings to determine how much radiation it really takes to create the basket full of problems advanced by the alarmists—we only do such things to rats and dogs.

But we do know something about telecommunications and radiation levels associated with over-the-air signal transfer and the production of electromagnetic radiation from signal wires and antennas. What was surprising about some of the speakers in this series was their own ignorance of actual power levels and behaviors of electromagnetic waves in telecommunications. No one in the business doubts that close proximity to a powerful antenna over extended periods of time will be harmful. Antennas must be turned off when workers scale an antenna tower to work on the tower or the antennas attached to it. Deep space antennas may produce signals with twice the power found inside a microwave oven, meaning they are carefully guarded. But antenna signals decay rapidly. Thirty feet away the level is 1% or less of the original signal power. By the time a signal sent from a mobile antenna reaches a mobile phone receiver, it is in much lower than the signal transmitted back to the antenna by the mobile phone. The actual behavior of the electromagnetic world as constructed today and as projected suggests that, should you continue using your mobile phone, you want to be as close to an antenna as is practicable, not further away.

Our Position

Our own position may be stated this way: (a) the highest signal levels received from an antenna for mobile phone connections that enable the phone to work are not harmful by any scientific measure; (b) the most significant possibility of harm comes from the cell phone itself; (3) cell phone signal power goes down in proportion to increases in received signal power, meaning the closer you are to an antenna the less radiation will be absorbed; and (4) the present typical uses of cell phones significantly reduce radiation absorption because signal power reduces so rapidly as the phone moves away from the ear (as in texting, watching videos, reading email, connecting to a Bluetooth ear bud).

An Apology

This material is technical and complex; we did not know how to make it otherwise without just saying what we have said above. But this is a seriously contentious issue with strident opponents of our view. Public policy questions of importance are at stake, namely, whether to allow small cell antennas in our communities and, if we allow them, under what conditions. We acknowledge that some legitimate studies suggest harm; we acknowledge that no study can eliminate long term effects until we have the long term, and we know our most constant source of radiation, the sun, has just such long term effects; and we acknowledge (as must the other side) that everyone is handicapped by not being able to test human beings directly. But we must make community decisions about antennas and their siting. An overly cautious approach would forbid them, an unnecessary deprivation of a critical human resource in our view. We believe we can have it both ways, get the antennas but control their location and power. But to counter the alarmists we must provide a more technical characterization of the radiation landscape than one finds in summaries from the Internet (although much of what we say is on the Internet).

What are the Basic Questions?

Electromagnetic Radiation (EMR) in the frequency range of interest (say, 800 MHz to 100 GHz, the full range of potential 5G frequencies) is non-ionizing, meaning that unlike gamma rays and X-rays, but like light, these frequencies do not dislodge electrons within a molecule (ionization) which may alter a cell’s genetic structure, kill the cell, or cause it to reproduce abnormally (cancer), although many cells so exposed actually repair themselves. However, such low frequency EMR does heat the water in cells (about 80% of a typical cell), and if high enough over a long enough period of time may cause the same kind of cell damage—change in cell properties, cell death, or irreversible pathological reproduction. A microwave oven, operating at 2.4 GHz with power as high as 1000 watts, does just that—heats the water in cells or teacups to the point of boiling. A rat placed in a 1000-watt microwave oven at full power would die in short order; we might take a little longer. Rats exposed to lower levels over extensive periods of time have developed tumors. No one is doubting that low-frequency EMR may be harmful at certain levels over certain intervals of time. The questions are (1) what are the boundaries in level and duration for human beings below which we are unlikely to be harmed and (2) are levels we absorb from our digital friends enough below that boundary to be considered safe.

The Basic Research Handicap

The hard part of the first question is that we do not know the answer in any definitive way, which makes answering the second with absolute confidence difficult. The reason we cannot definitively answer the first question stems from our understandable reluctance to conduct controlled risk experiments that subject human beings to increasing levels of radiation over increasing periods of time until the test subjects suffer cancers, other malignancies, sleeplessness, cognitive deficiencies, or any other potentially permanent impairment. We are willing to do this to rats and other animals, and test have been done on mice and rats that suggest dangers at least to male rats. But rats are notoriously bad at simulating human responses. So other measures have been applied. Some are epidemiological, trying to study actual effects on real human beings through correlations between trends in various impairments, principally cancer, and growth in cell phone use. One of the more than 20 studies done over very large populations around the world suggests positive correlations, but cannot establish actual causes; the others are all negative (no correlation). Many studies have also been done on people with actual brain tumors (say) to see if their incidence can be correlated with cell phone use or the nature of the tumors suggest radiation as a cause; no consistent affirmative pattern has emerged. Some have tested known disorders in small populations of people who live very near powerful antennas compared to similar small populations who live further away (the one we read was in Egypt); while still just a correlation, the radiation levels at the base of a macrocell tower are considerable, and very much higher than what you receive at your cell phone a further distance away. Other tests have been done in laboratories, testing mice and rats in controlled experiments, testing human cells in Petri dishes, examining penetration levels of radiation in human tissue among others.

We call attention to the two studies most frequently cited by those opposed to small cell antennas in our communities—the BioInitiative Report of 2012 and the National Toxicology Program report of 2018, the former a compilation and commentary on many studies showing harm, the latter a study of rats and mice subjected to radiation over two years. These can be found on the Internet, along with a number of reviews of their merits or deficiencies. Plan ahead; they are very long.

Standards for Cell Phone and Mobile Antenna Power Levels

Two organizations in the world set standards for maximum power output levels from mobile phones and antennas—the FCC for the United States and ICNIRP— International Commission on Non-Ionizing Radiation—for the rest of the world. The maximum allowable power level from a mobile phone in the United States is 1.6 watts/kg, a measure of Specific Absorption Rate (SAR), which translates roughly into 3 watts of output power. No phone on the market today produces a transmit signal that high. Apple phones have a maximum output of 1.08 watts/kg, Samsung phones tend to be much lower at 0.4 watts/kg, largely because Samsung phones use an antenna that directs power away from the ear. But maximum transmit power is rare in practice. Because transmit power is the largest drain on mobile phone batteries, every smart phone reduces output power in proportion to increases in received power, sometimes down to transmit levels near 0.001 watt/kg, or around 10 milliwatts. One study of actual output levels shows the average in urban areas to be around 0.10 watt but closer to 0.40 watt in rural areas where antennas are much further away on average.

Receive Power Levels

A smart phone has a range of power levels it can receive. It has a lower bound (around -120 dbm, or 0.000000000000001 watt) and an upper bound (around -40 dbm, or 0.00000001 watt). We call the levels in between the “dynamic range.” The range arises from how receivers are built. Any receiver today will take in a signal, sample it at a sampling rate at just over twice the highest frequency of interest, convert each voltage sample into a digital word, and then operate on the sequence of samples in the digital domain. To operate effectively over such a large range of levels the input of the receiver includes an automatic gain control (AGC) in the analog domain. An AGC measures an incoming signal and amplifies any signal lower than the specified maximum so that its peak level is consistent with the maximum. This creates received signals with constant amplitude across the entire range before analog-to-digital conversion. However, samples taken at peak levels of signals above the maximum level will be equal to samples at the peak of the maximum level, essentially clipping and distorting the equivalent waveform. At some point not too far above the maximum acceptable level the signal becomes useless. So, if one gets close enough to an antenna that receive signals levels get significantly above -40 dbm, the mobile phone will just stop working as a communications device.

We can be astonished that mobile phones can operate at such low levels, but we can recognize at the same time that a remote antenna powered by a 100-watt source produces a signal that dissipates rapidly relative to a single mobile phone. Such an antenna has a range of 20 miles when connecting to a standard mobile phone receiver. At twenty miles its effective signal level has decayed by 17 orders of magnitude. Even 200 feet away the signal has dropped five orders of magnitude, to around a milliwatt. (If you want to run some numbers, the power reduces by 1/4pr², where r is distance in meters.) Small cell antennas mounted on telephone poles with ranges around 2 miles have transmit powers around 10 watts; smaller cell antennas are proportionally smaller in output power because more power does not help the mobile phone itself. Antennas are not the problem; if there is a problem it is cell phone transmit power.

The Potential Danger

Non-ionizing EMR at certain levels heat human cells beyond the body’s natural mechanisms for absorbing higher temperatures (say, from running or taking a hot bath). Furthermore, there are suspicions that non-ionizing radiation has other effects unrelated to heating. As noted above, we do not know what these levels are or what exact problems ensue because we are not going to conduct controlled experiments on human beings. So we look for indirect evidence. Some of that evidence is entirely anecdotal—doctors reporting that patients complain of not sleeping after moving their cordless phone next to the pillow, early onset of menopause caused by a new smart meter installed in a home, depression relieved by moving the WiFi router away. We presume that doctors reporting these experiences believe what they are reporting, and others apparently believe them. But none of these experiences have risen to statistically relevant levels given the profusion of WiFi routers, smart meters, and cordless telephones in the world today.

The most serious potential effects are cancer and non-cancerous abnormalities related to hearing. Radiation from the sun (most at higher frequencies but still non-ionizing) kills a million people a year world-wide, often with latencies measured in decades. So thousands of studies of potential effects on humans caused by human generated radiation have been conducted. Here is the World Health Organization’s present assessment:

In the area of biological effects and medical applications of non-ionizing radiation approximately 25,000 articles have been published over the past 30 years. Despite the feeling of some people that more research needs to be done, scientific knowledge in this area is now more extensive than for most chemicals. Based on a recent in-depth review of the scientific literature, the WHO concluded that current evidence does not confirm the existence of any health consequences from exposure to low level electromagnetic fields. However, some gaps in knowledge about biological effects exist and need further research.

To date no government organization has insisted upon a reduction in standardized transmit levels from antennas or mobile phones. The International Agency for Research in Cancer (IARC, a division of the World Health Organization) issued a report in 2011 that claimed that mobile phone radiation should be classified as “could be harmful” based on enough reports showing harm, but did not then nor has it since classified such radiation as harmful. In the United States the Center for Disease Control, the National Institute of Health, the National Cancer Institute, The Food and Drug Administration, the Environmental Protection Agency, and the Occupational Safety and Health Administration, all federal agencies, continue to support FCC levels. The EPA reflects the same sentiment as the WHO:

Some health and safety interest groups have interpreted certain reports to suggest that wireless device use may be linked to cancer and other illnesses, posing potentially greater risks for children than adults. While these assertions have gained increased public attention, currently no scientific evidence establishes a causal link between wireless device use and cancer or other illnesses. Those evaluating the potential risks of using wireless devices agree that more and longer-term studies should explore whether there is a better basis for RF safety standards than is currently used. The FCC closely monitors all of these study results. However, at this time, there is no basis on which to establish a different safety threshold than our current requirements.

Some claim that government agencies collude with private carriers to serve their interests. Some clear evidence exists for the current FCC in this respect, particularly with respect to the general subject here, of broadband communications. But any understanding of government bureaucracies would preclude a cabal among all of these agencies—they are way too disconnected to suffer a common cause, even one imposed from above, nor are scientists working for them so corruptible that they would wittingly advance opinions adverse to their own work. We are not saying they are right; they are not saying they are right. But they represent a global sense among important institutions that no compelling evidence exists to significantly drop current radiation standards.

With All Due Respect

We are not advocating wholesale dismissal of those concerned by prospects of harm from EMR. Nor are we defending in any unusual way government adherence to present transmission standards. There is no reason to doubt the sincerity or intelligence of those within the scientific community alarmed by what they have found. While there are reasons to doubt their studies and conclusions, there are also good reasons to doubt studies that reach opposite conclusions. Such is the complexity of the subject and the limitations imposed by not making risk assessments on humans directly. We do reject the conspiracy theories and summary judgment by those who insist that governments the world over just serve corporate interests, are bought by them, and hence ignore all the evidence for real harm at current transmission levels. We live in a world with risks. Some we know a lot about, such as smoking and obesity and excessive exposure to the sun. We have not outlawed any of these activities. Some we know very little about—global warming, screen addiction, mental illness including depression, and the long term effects of electromagnetic radiation from mobile phone use. The collective ruling today is that current levels of mobile phone radiation are not harmful. It is the case that levels received from a remote mobile antenna that are low enough for the phone to operate are not harmful. It is just as certain that moving closer to an antenna reduces radiation absorption under normal conditions. And it is just as certain (although not discussed here) that using a mobile phone away from the ear, say in texting, watching a video, or connecting to the phone with Bluetooth ear buds, significantly reduces absorption.

A final note: transmission over fiber optics does not produce electromagnetic radiation (unlike transmission over copper-based twisted pair or coaxial lines with mismatched impedances at each end). So if you are really worried, then please get on the fiber optics bandwagon.

So What Are We To Do?

In a 2018 ruling the FCC limited the fees a municipality could require to process a small cell siting application to $270, and limited the time such an application would require to 60 days. Both conditions are unreasonable, trespass on traditional municipal rights, ignore municipal concerns about radiation, and likely cost municipalities money as $270 will often fall short of required costs. More than 20 municipalities, almost all on the west coast, sued the FCC in federal court; that suit is now in oral arguments, but it will not be settled quickly. Municipalities should want small cell antennas for the reasons we have given above, but they should also be allowed to control their location, orientation, and maximum power levels. Should a mobile antenna company wish to install small cell antennas here, we suggest that the summary answer within the 60 day window be no, that the proposing company then negotiate with the municipality a suitable time frame and conditions for deployment, and the municipality be prepared to assess and control location, power levels, and orientation of any small cell antennas installed in their towns. It would also be advisable for municipalities in our region to select a task force with suitable knowledge and approach Eversource with our concerns. Eversource administers the poles in our area. They have no investment in mobile telephony, but they to have an investment in pole life and use. They should be part of the conversation.