FCC Presentation on RF Limits to USTTI: Transcripted Version
USTTI: FCC Webinar October 15th – Human Exposure to Radiofrequency (RF) Fields
In this webinar Martin Doczkat an Electronics Engineer at the Federal Communications Commission presents on FCC limits and regulations for radiofrequency radiation.
Note: This transcript starts midway through the webinar.
USTTI Presenter:
…Animals.
Martin Doczkat:
So that means that they would either limit their food intake or change their behavior in certain ways. And it turns out, that’s the most sensitive effects that we are able to observe in scientific studies. And when the scientists take this information and derive human exposure limits, it also turns out that humans are much better than a lot of other animals that were used in these studies at regulating the temperature. But to make sure that the limits that are established are safe, there are safety factors that are applied. And this is a common application of factors such as 10, or five, or even higher values. If if there’s certain dangers, such as some chemicals that are known to cause acute harms in humans, that there are different safety factors that are applied. In the case of RF exposure, the initial number for watts per kilogram is taken and divided by 10, to come up with the occupational exposure limit for the whole body. And then it’s divided by five again, for a total factor of 50. For the general public. And these are the basic restrictions for the human exposure limits. So that’s the whole body exposure and the general understanding or terminology associated with whole body exposure. But the newer exposure limits take the various mechanisms of interaction with the human body and split them up into a number of different additional categories beyond whole body exposure. In the three to 100 kilo hertz range, we’ve got other effects that don’t have to do as much with heating, they have to do more with nerve stimulation in the human body. And these are sudden instantaneous effects that can occur when you can induce an action potential on a neuron. So you have things like shocks and burns, or normal involuntary muscle contractions that can occur between three and 100 kilohertz. Above that we’ve got specific absorption rate that we’ve already covered. And then above about six gigahertz, you have localized power density, that’s more of a surface heating effect. And so you have fuzzy optical behavior. And it’s not as well absorbed deep in with within the human tissue, like, we, like what happened between the 100 kilohertz and six gigahertz range. So between three and 100 kilohertz, we’ve got industrial heating equipment, RFID other types of devices, like wireless power transfer, charging equipment, which is kind of a newer one. Where the wavelengths are so large that the fields don’t significantly interact with humans unless you’re really close to them. So you’re talking about near near contact, or close to direct contact. And this is for things like the limbs. For example, if you are near an am radio station with potential at the base, that there’s a potential for a spark discharge or something that can happen that would lead to harm, such as an RF burn that could occur within those frequencies. Most radio transmitters are within the 100 kilohertz or six gigahertz range, the waves penetrate deeply within the tissues, or they can penetrate deeply within your tissues. And again, we mentioned this already the four watts per kilogram, and how the limit was derived. Some tissues, for example, the eyes, the testes, have limited thermal regulatory ability and require specific, more restrictive limits. And these are produced in the standards and in the form of localized exposure limits, rather than whole body exposure limits. So there’s another SAR value that applies for localized exposure, in particular for for things like the eyes that have a specific geometry and consideration when you have transmitters, such as phones that are used against the head or near the body.
USTTI Presenter:
Martin, we’re, if I can, I’m going to just pass along some of the questions here that have come in here as we’re going through. The first one is what is the safety factor the FCC puts forward for localized SAR-[You] say it is 50 times the whole body SAR, but what about localized SAR?
Martin Doczkat:
Yes, it’s a good question. And I guess I’ll get into a little bit more about the standards that the-that the FCC uses. I did want to cover sort of the general background here first before we get into what limits we use. And it does get a little bit complicated, because you have to go back to the standards that we use and how they were derived. There’s two different methods of deriving the, the localized exposure limit. One is the one used by the FCC in terms of its rationale, which was a little bit older, because it relies on standards from the 80s and the 90s, where they considered the variation of the fields in the localized sense and what how how much variation can be tolerated while still complying with the basic whole body exposure limit. And it turns out that that variation can be at a minimum 20 to one. So that’s, so it’s actually starting from four watts per kilogram going down by 10, then another five, then back up by 20, with the rationale that there’s variation in the fields, the newer standards, such as the ICNIRP 1998 standard, the IEEE 2005 standard, and more recently, the IEEE 2019. And ICNIRP 2020 standards is a different rationale. They look at actual thermal analysis of the eyes, the outer ear and other things in the body that are roughly in in 10 gram weights, and especially close to transmitters such as phones, and they derive the limit somewhat differently. So you end up having-and I’ll I’ll show this a little bit later on, you end up having two slightly different standards between some of the newer standards and and the way that the FCC does it. The practical effect is that there’s about a two to one difference, the FCC limits being slightly one by one half, roughly the amount of the other prevailing international standards.
USTTI Presenter:
Regarding the as you were talking about the towers and being very close, one of the questions came in is, is that the reason why there are so many dead birds near transmitting antennas for radio and TV stations?
Martin Doczkat:
Yeah, I I’m not an avian biologist, I’m not really sure of the answer to that. We did open a an environmental assessment a while back to look into that very issue, especially migratory birds, which have lower tend to have lower populations, and many of which are endangered. And you could probably look for it online, was a very public process where we looked at the impact of antenna structures on migratory birds, a lot of it had to do more with the the types of lights that are on the facilities, as well as the guy wider wires of some of the towers that aren’t lit. And it turns out that birds are more more sensitive to some types of lights, such as strobe lights, than they are to the red flashing red slowly flashing lights. So it has to do more with the birds’ ability to detect the tower, the presence of the tower, especially in the middle of the night when it’s dark, and they can’t see as well. And it has less to do with the exposure itself. However, there are some really interesting studies out there that look at, for example, am radios’ impact on bird navigation. It’s still sort of a somewhat obscure and not really popular scientific research angle, but there are papers out there that sort of talk about that. But if a bird were to fly through, let’s say a high power antenna field, they wouldn’t be there for very long. So it’s likely that unless there was actual direct contact with the antenna, which you’d probably have to worry about more physical harm than anything else, that they wouldn’t be significantly heated very much. So I think it’s probably more likely to do with the the towers themselves and the birds’ ability to be able to detect them than it is to do with the RF exposure.
USTTI Presenter:
Very. There’s a question about the exposure for the individuals during link alignment. Is there an effect for the rigger who is going up? You know, with any exposure they may experience?
Martin Doczkat:
Yes. So so in fact there are we have worker safety considerations when it comes to tower work and tower climbers. There are we have a couple of health agencies in the United States, one of them being our Occupational Safety and Health Administration. And they have they have guidelines that are called lockout tagout. Where if you have especially high transmitters, high power transmitters with the potential for high exposure for workers, that you turn off the transmitters completely, and you lock them, and you tag them, which means that you have a sign on there that tells people not to turn them back on or unlock them so that the workers remain safe. There are much more involved radio frequency safety programs that could be established at certain sites to allow the service to continue while the work is happening. But it involves a much, much more rigorous engineering analysis. But absolutely, that’s something that you need to look into for making sure that the the towers, tower workers especially are safe when they’re climbing. And already frequency exposure is one factor to consider. But obviously, gravity is a big one. So they need to make sure that they’re they’re clipped in and they’re they’re climbing safely so that they don’t fall because tower deaths remain a higher concern than their exposure itself. But but it is something to consider.
USTTI Presenter:
Another question here, frequency was considered as a factor to distinguish between ionizing and non ionizing emissions. Is there any consideration of the power of the different sources? Or is power not a factor to be considered in non ionizing emissions?
Martin Doczkat:
Yes, absolutely. So so I think the point, and I think I might get into this a little bit later on, but that’s the point that we’re trying to to drive home here is that the four watts per kilogram is is a power limit. So above that, you have the possibility of a number of health effects that could occur. And that’s what we’re trying to prevent. So, so yes, frequency is one component, but power is the other. So um, so what we’re trying to do is to limit that power, so that the amount of absorbed energy doesn’t result in harmful effects in humans.
USTTI Presenter:
Another one here, and many good questions, Martin, coming in-Does the do the exposure standards or limits of indoor and outdoor differ? Do the limits and stand are the limits and standards based on the nature of the network?
Martin Doczkat:
No, they’re not there, they’re independent. So it has to do and and in fact, I’ve measured both outdoor and indoor antenna systems. And there, it it so happens that the powers from the the indoor systems are lower. So the region of exposure, compliance is smaller. So typically, they’re up in the ceiling and past where the head height would be. So there’s very little concern there. But the the limits themselves aren’t different. They don’t depend on deployment architecture, they don’t depend on technology or anything like that. They’re basic limits that have to do with the physiology, and the mechanisms of interaction with human body itself. So whether it’s 4g, or 5g or 3g, or 2g or whatever other G’s there are out there. The the amount of energy that’s actually absorbed in the body, is is that considered the primary consideration?
USTTI Presenter:
And this gets to one of the more just direct questions that has has been asked. Is it safe for humans to live around a telecommunications tower? It’s been installed.
Martin Doczkat:
Yeah, so as long as those fields are compliant, that’s the intent of the limits themselves. So what what we do is we ensure that the we emphasize that the facilities have to be compliant, so as long as it’s compliant, then then there shouldn’t be any other concern. And keep in mind that as I showed earlier, there’s a significant safety factor below the actual observed health effects that are that would occur. So you’ve got a huge margin built in already. And then just another factor here is that whenever antennas are roof mounted, or if they’re pole mounted, they’re generally high above ground. So the energy and compliance region, which is the region where the general public limit would be exceeded, tends to be within the same the front frontal area of the antenna and not above or below it necessarily. It’s usually within that same region in front of the antenna.
USTTI Presenter:
And something here that that has been asked and at what level might RF affect human reproduction?
Martin Doczkat:
Yeah, so so I think we might cover some of that. There there are definitely scientific studies that show that human reproduction can be affected at high levels of exposure. And that’s what we’re trying to limit. And that’s what we’re trying to avoid by having the limits. That’s one of the main purposes of the limits. It’s not just, you know, I mentioned earlier, in fact, on this slide, too, I mentioned the testes is one, one area where the exposure can be high and thermal regulation is not especially good there.
USTTI Presenter:
There are multiple questions that are here about 5g in millimeter wave, I think I may want to give you the opportunity to continue with the presentation, as I know, it may answer some of the questions that that have been raised.
Martin Doczkat:
So yeah, and you’re probably familiar also, that with 5g that the United States has, it has a hybrid approach, where we’re looking at low band, mid band and high band spectrum. But there’s a special emphasis in the United States of of exposures from 5g base stations in the millimeter wave bands, which are above six gigahertz, so it’s timely to raise that. So especially when it comes to exposure to millimeter waves, such as above six gigahertz. In the case of the United States, it’s 24 gigahertz and above. The exposures were uncommon, but there are now a number of new technologies being deployed in those frequencies, the wave, the penetration of waves is very shallow tends to be mainly within the skin itself. And it’s caused the optical so you have at high levels of exposure, things like localized heating and burns that can occur on the surface of the skin, or cataract formation in the highs at very high levels of exposure. So here we go with the adverse health effects and what can happen if you exceed these limits. So heating is the primary effect. So we’re talking about radio frequency exposure, and that’s what we’re trying to avoid. So known effects that occur at high levels, as I mentioned, were cataract formation, which is in the eye, and changes in blood brain barrier permeability, changes in calcium flux rates, behavioral changes, as I mentioned with the animal studies, chromosomal effects, retarded growth potential, central nervous system changes, auditory perception and sterility and other new reproductive effects that could occur. Then, and again, I’ll emphasize that this is at high levels. And these are the these are the various effects that we’re seeking to avoid by setting the levels of exposure low enough such that they don’t occur when sources of energy are compliant with the limits. So here’s sort of the controversy and why this is usually such a hot topic is when it comes to exposure, the exposure could lead to some biological effect. And it’s a question of whether that biological effect is is adverse or not, and whether the science surrounding that effect is sufficiently well established. So where do the scientists that are responsible for developing the the standards place the line? So what how do we set this safety margin? And and it’s still an outstanding question. The the safety margin itself has remained relatively constant over the years. But there’s also differing perspectives between the standards groups as to which effects are adverse or not, for example, when it comes to microwave hearing, some might say that, if you can hear something, it doesn’t necessarily harm you. But others might say that it’s it’s annoying, or that there is some adverse nature to it. So it’s, so it’s a question of of where do you place that line. And when it comes to the effects that are known and well understood, again, we’re talking about thermal effects and in terms of energy absorption. And there are still various studies out there that are looking into the long, long term effects of of radio frequency exposure, and but they still remain to be not very well established. But but they’re out there and they’re worth looking into. It doesn’t mean that the standards should necessarily change as a result, but it’s it’s something that, of course, the FCC would encourage more research to continue to continue looking into things like that. So how are the safety standards set? There are groups of scientists with specialization across many disciplines. And there’s a consensus approach. So when you have these studies that look at non thermal effects, or long term health effects, or however you want to classify them, you know, first off, it needs to be not a single study, and it needs to be repeatable. And it needs to show consistent results across the studies. And is to be published with sufficient rationale and a clear understanding of the amount of exposure that occurred within the study. So there are a number of studies which can be dismissed, because it might be something like cell phones were placed on the top of the animal’s cages. And in that case, because there’s power control, and they’re scattering from the cages, and the animals are moving around, it’s not very clear about what exposure the animals received in those types of studies. So it’s helpful to have higher quality studies that show a very clear linkage between the exposure and whichever effects being observed or claimed in those studies. And obviously, it helps for repeatability to make sure that other labs can replicate the effect or the result. And and that does happen a lot. So there’s a lot of work that’s happening now to replicate some of the more recent studies that that are out there. So scientific research itself leads to peer reviewed publications. So you’ve got journals that that act as a gate to to make sure that the science is of sufficient quality to be published. And then that leads to the consensus standards. And there’s deliberation in the consensus in the standards groups themselves about whether one study or another is significant, and of sufficient quality, and is showing a clear linkage of between the exposure and the health effect such that the limit should be established for those types of studies. And then eventually, that leads to the regulations once the regulator’s decide in their public processes that the consensus standards are sufficiently protective of the public at large.
USTTI Presenter:
Martin, I I just want to interrupt momentarily. And we have a colleague actually from a think tank based in the United States who has been offering some questions and and want to give the opportunity to address these before we keep getting further down in in because she is raising some issues and some concerns, and I don’t want it to seem as though we’re not addressing them.
Martin Doczkat:
So why don’t we just one, how are we doing on time, by the way?
USTTI Presenter:
We we are great, we have a significant amount of time. I want to give you the opportunity to respond to some of these that are being raised in the q&a and and also in the chat section and and and Theodora asks, you know, several questions here in the first that I’ll get to is in terms of what you were just addressing is she makes the claim that the FCC is rejecting the National Toxicology Program study. And the question is, why is the FCC doing that?
Martin Doczkat:
Okay, so that’s actually one of the studies I was referring to the NTP study that is actually being replicated by a number of researchers worldwide. Presently, for example, there’s an ongoing research efforts in Japan and Korea, as well as by the NTP itself to look at some of the additional follow on studies that they’d want to do. I wouldn’t say that we’re rejecting it.
USTTI Presenter:
Right and that she also asked the question is what about the studies showing memory damage from phones? Replicated research, changes to sleep EEG that have happened at levels below FCC limits?
Martin Doczkat:
Right. So right, so obviously, I mentioned the EEG studies before, and the scientific consensus is that there that these effects happen to occur at the levels above where the limits are placed.
USTTI Presenter:
And again, I just want to ensure that we’re, you know, getting these and addressing these because they’ve been coming through a little bit rapid fire and were the did the FCC create limits to protect trees and insects. And are these limits developed? The, you know, with any thought of protecting trees and insects?
Martin Doczkat:
That’s a good question. So we, the limits in the rules themselves are referred to human exposure. And that’s really the the main the main purpose here. You know, however, as I mentioned before with the birds, is that the national that the NEPA requires that we look at the environment as a whole, so it wouldn’t necessarily be something that would, you know, out be out of the question, it’s just that the way that the standards are designed, it happened to be with relationship to humans.
USTTI Presenter:
Okay, and then Theodora has one more that she keeps coming back with. So we’re we’re gonna she keeps, she wants to know, the safety margin for localized exposure as priority.
Martin Doczkat:
I’m sorry, I don’t understand the question.
USTTI Presenter:
Yeah. And and and that is and and and perhaps Theodora, if you can just put that in the chat, I’ll look at that and and pass that along to to Martin, maybe more clearly, in in more information, but for for now, Martin, we’ll we’ll give you the opportunity to continue and and the question is, what is the safety margin for localized SAR?
Martin Doczkat:
Think I already answered that.
USTTI Presenter:
If if maybe you could just provide that again. And you know, as it was asked, just one more time.
Martin Doczkat:
Um, yeah, I’m just gonna move on.
USTTI Presenter:
Okay.
Martin Doczkat:
So, so anyway, the except I don’t want to I want to make sure we have enough time. So the disciplines mentioned here are some of the overall expertise areas that comprise especially the group of the I mentioned the International Commission on Electromagnetic Safety. So you’ve got various disciplines there, such as you know, perception, behavior, etc. And again, the safety standards go over whole body SAR, localized SAR, current density limits and reference levels, such as electro electromagnetic fields as well as power density. So just sort of quoting what at least one of the standards groups say is that there’s no verified reports that exist of injury to intact human beings, or have adverse effects on the health human beings within the standard established limits. So I’m just going over some of the the FCC standards, we’ve got the National Council on radio Radiation Protection and Measurement, which is a congressionally chartered organization, which we use for the external field strengths to measure electric and magnetic fields as well as power density. And then complementing that is the IEEE standard, for Specific Absorption Rate. And we selected the most restrictive aspect of of each of those standards. And as I mentioned before, the more recent standards actually have less, less restrictive limits, especially when it comes to localized exposure. And these were adopted based on recommendations of the US health agencies, including FDA, EPA, OSHA, and also within within the public. So just to to show the whole body exposure again, here, we’ve got this is the NCRP, US FCC limit. And we’ve got occupational exposure, which is the pink line there. And as you, as you can see, the public limit is reduced by an additional factor of five. And we should mention that you’ve got in the sort of 30 to 300 megahertz range, a dip in the the standards themselves where it turns out that the body happens to be more more resonant, especially for whole body exposure. So you’ve got increased amount of, you know, restriction there to allow for that. And I should mention also that this is the ICNIRP 1998 standard, there’s a new standard that we’re we’re still looking at, but just for basis basis of comparison here, this is the this is the other international limit that exists and as you can see, there’s a similar, similar restriction between roughly 10 and 300 megahertz where there’s a lower limit to to the body resonance has a general similar shape. And then we’ve got some differences, especially at lower frequencies. And that’s because the, the frequency scope of ICNIRP expands beyond what the NCRP established in 1986. So just comparing the two, you have a generally similar comparison where you’ve got two different sets of limits, and they tend to follow a similar trend line. And so as you can see, there are differences, but especially when it comes to most common frequencies used for telecommunication sources, especially, that there’s a lot of harmonization there. So how do you measure the, the exposure, SAR itself or the absorption of energy in human tissue can’t be measured directly in living organisms. I think it would, it would, it would hurt if you had to stick a probe around your body to try to measure it. So we come up with ways to measure as an approximation to absorption in living organisms by measuring in different ways, so the power density can be inferred by the electrical magnetic fields. And in the far field, it’s easier just to measure the electrical magnetic field strengths without the presence of the body. So for portable portable devices, we’ve got external magnetic fields from the phone, and they induce internal electric fields in the head or the body, and that’s where the, the measurements would occur. And that’s how SAR would be measured. And SAR is proportional to the square of the electric electric field and is normalized by the electrical properties within the head or the body. And and that’s how SAR ends up being measured. So for localized exposure, as I mentioned earlier, the FCC sets a limit of 1.6 watts per kilogram and one gram of tissue compared to the other international standards that set a limit of two watts per kilogram and 10 grams of tissue. And it’s less to do with the the watts per kilogram than than it is to do with the actual averaging mass itself, which leads to the difference as I mentioned earlier, the two to one difference between the FCC limit practically and the IEEE ICNIRP limits. And just to preview here, so you’ve got how portable devices are measured, there’s an antenna or a probe that’s attached to a robot and the robots scans around within tissue simulating liquid to measure the the fields that would exist within the head or the body and you get distributions like this. So, you can see here, how the distributions would exist within the head from from a phone or something like that. And when it comes to measurements of the electrical magnetic field strengths, probes are designed to measure the three orthogonal components of the electric or magnetic fields. As you can see on on the left hand side, there are what you would call dipole antennas that measure the electric field or loop antennas that can measure the magnetic field and what the three components are sum together to come up with the overall result into electric or magnetic field. So to summarize, electromagnetic fields interact with humans with effects that vary with frequency and dielectric properties. We also mentioned power is a is another factor. The study of the effects is multidisciplinary and most exposure limits are are based on threshold of established adverse health effects. The most sensitive threshold is behavior and it’s so well established well understood and precedent that we have within the limits themselves. And exposure parameter SAR is not easily measured, so we rely on electromagnetic fields for the limits. Just one other note, the FCC published a rulemaking at the end of last year at the end of 2019 that had some decisions. And here’s this is the link for that document. So you probably can find more information there. I think my last slide’s questions, but I’ll pause here. If there are any questions for now in case anybody would like to take that link down.
USTTI Presenter:
There are a number of them that have come in from from our colleagues around the world. And and I’ll do our best to go through some of these. And to our developing country officials, one of them is as it relates to COVID, and did the question at a statement and then question that there’s more news coming from different corners of the world talking about the benefits of 5g. But there are great concerns related to the danger of signal power from 5g. So far, this individual has not gotten a chance to see someone from an organization like the FCC, WHO, ITU, GSMA or 3GPP denouncing this news. Can you explain or maybe even sin, you know, talk about some of the papers that have been out there? That’s my editorial comment regarding the health concerns of 5g in the link to you know, COVID, or the non links to COVID.
Martin Doczkat:
Well, so for the the links to COVID. I mean, I guess I could refer to the World Health Organization and I, I’m sorry, if I’m not being as much of a mythbuster as I as I probably could be, but there there there are. In fact, it is called a mythbuster page on the World Health Organization webpage for various rumors that are exist for for 5g and, and for COVID-19. So you can probably look there for for references when it comes to 5g base stations or anything else on the information for the devices that exist, at least within the US, and how they demonstrate compliance with the FCC limits. They all are publicly available. So if you go to the FCC equipment authorization page, for especially part 30, which is our upper millimeter wave, flexible use spectrum, which is our millimeter wave 5g Radio Service, you can look at the compliance exhibits there and look at the the spatial region for compliance of those types of facilities. And as I mentioned before, just like with other radio base stations, the fields where the limits might be exceeded tend to exist within or surrounding the surface of the antenna, they don’t extend much farther beyond the surface of the antenna, in the case of the 5g base stations, it’s tends to stay within the same height as the antenna, even with the dynamic antennas that they have. And when it comes to the distance from the surface of the antenna, it’s not too large, it tends to be within the one to four meter range. So if you can imagine a base station that’s on a pole or something like that, if it’s next to a sidewalk, that that type of distance would be the the general region. And again, the antennas are mounted well above the ground, that that would exist for compliance of those types of antennas.
USTTI Presenter:
And as it relates to enforcement, there is a question about what does the FCC do if there is violation of rules regarding limit exposure to RF fields?
Martin Doczkat:
Well, there are a number of different enforcements… Are you do you have somebody coming in for enforcement later or?
USTTI Presenter:
Not not today, but that that would be a future webinar that we do really.
Martin Doczkat:
So I don’t work for the Enforcement Bureau. So full disclosure there, but but the Enforcement Bureau has a number of various tools at its disposal. It can issue a number of different types of enforcement actions against licensees, for example, notices of violation or notices of repair of liability, which have happened in the past for some cellular base stations. And they’re all a matter of public record. And in some cases, that results in forfeiture notices, which would be a fine. So, yeah, so there we’re obviously I said earlier that the FCC is emphasizing compliance to the extent that there are any cases out there we would investigate and if there was noncompliance, we would we would issue some sort of enforcement action.
https://ehtrust.org/fcc-confirms-no-limits-for-impacts-to-environment-refuses-to-answer-question-about-safety-factor/ Source: Environmental Health Trust