Radiofrequency Exposures, Radiofrequency Exposures, Occupational Safety and Potential Health Occupational Safety and Potential Health

EffectsEffects

Andrew H. Thatcher, MSHP, CHPthatcher.drew@comcast.net

OJUA Annual MeetingOctober 4, 2018

Redmond Oregon

Outline What are Radiofrequency

signals Examples in our enviroment Types of antennas used and

compliance distances Discussion of Health Effects

from current cellular antennas and the proposed 5G antennas

The Electromagnetic Spectrum

|Radio-Frequency RF Radiation

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Types of InteractionsTypes of Interactions

Current Induction; “electrostimulation”

Atomic / Molecular Vibration;“heating”

Photochemical Interactions

Ionization, E > 12.4 eVIonization, E > 12.4 eV

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All wave motion can be described in terms of wavelength and frequency (f) and wave velocity (v)

v = f · For light, the velocity v =

c and

c = f · λ

vv

Characteristics of all Wave Motion

Wave Terminology Comprised

of an E field and H field

Polarization

The Current RF SpectrumThe Current RF Spectrum

To put these exposures into perspective, if the top of Mt. Bachelor is the allowed public limit, the maximum outdoor exposure is ~225’ highCopyright ©2018

Andrew H. Thatcher,

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Cordlessphone

Bluetooth BabyMonitor @

7 feet

FM & TV WirelessLaptop

WiFi Macro sitetypical

outdoorexposure

Small Cellsite typical

outdoorexposure

Typical Radiofrequency Exposures in our Lives

The Public exposure limit is: 200 µW/cm² for FM425 µW/cm² for TV (UHF)570 µW/cm² for cellular1,000 µW/cm² for PCS

Copyright ©2018

Andrew H. Thatcher,

Near Field and Far Field ExposuresNear Field Far Field

Radio Waves: Pathway Radio Waves: Pathway Propagation and LossPropagation and Loss

In the perfect world – all signals are direct path and there are no path losses (Line of sight)

Three primary components are reflection, diffraction and scattering.

We know a great deal about this for the 3G and 4G frequency bands currently used.

As frequencies increase, the propagation and diffraction losses are increased

Signal Path Loss

For tree canopy signal attenuation could easily result in signal attenuation of a factor of 10 to as much as 100 fold

In an urban environment, the presence of buildings results in diffraction and scattering of signals.  These hard surfaces may actually prove beneficial in the 5G environment

Building and Path Loss

At broadband wireless frequencies, the penetration loss entering a building often exceeds a factor of 5,000.

• This restricts range so greatly that antennas are almost never located inside a building

At broadband wireless frequencies, trees and other vegetation effectively block and absorb the signal.

• Typical attenuation for just one mature tree can be a factor of 100 or more

Foliage and Building PenetrationsConsiderations

Macro Sites versus Small Cell

Terrain Challenges

Tall Buildings

Large residential areas

Make efficient use of available spectrum by re‐using frequencies in a geographic area (also a big advantage of 5G)

Macro Antennas

Are these people in harms way?

How can you know you’re safe?

Maximum outdoor exposure from proposed antennas operating at 100% power 5-100 µW/cm²

The likely outdoor exposure near the proposed antenna is <10 µW/cm²

Small Cell Exposures –

Strand Mounted AntennasStrand Mounted Antennas Strand mounted antennas – generally

an omni antenna, 10 watts combined power.

General public exposure limit on the order of 1 foot.

What the Future Holds for Small Cells in Terms of Power Levels

Current typical small cells use 5 to 10 watts of emitted power so with a typical antenna gain the Effective Radiated Power ~500 to 700 WattsAttachment heights of current small cells

range from 20’ to 45’

Safe Distances for 5G?Safe Distances for 5G?

https://www.itu.int/en/ITU‐T/Workshops‐and‐Seminars/20171205/Documents/S3_Christer_Tornevik.pdf

One study of a 28 GHz antenna showed that the public limit was limited to within 5’ of the front of the antenna

3.5 GHz 5G Site with 3.5 GHz 5G Site with Massive MIMOMassive MIMO

https://www.itu.int/en/ITU‐T/Workshops‐and‐Seminars/20171205/Documents/S3_Christer_Tornevik.pdf

Analysis of 3G, 4G and 5G site using theoretical maximum power can yield large exclusion areas

3.5 GHz 5G Site with 3.5 GHz 5G Site with Massive MIMOMassive MIMO

https://www.itu.int/en/ITU‐T/Workshops‐and‐Seminars/20171205/Documents/S3_Christer_Tornevik.pdf

However, analysis of 5G using actual maximum power yields more realistic results.Two factors for compliance in the U.S. – analysis requires use of theoretical maximum power and a time component 

How are exposures different in mid and upper band 5G

Traditional FCC guidance with multiple beams in a high gain environment could result in sites exceeding public exposure limits.  By using realistic power levels based on time averaging sites could be shown to comply with standards

More on 5G Compliance More on 5G Compliance DistancesDistances

Finally, a study on a 2205 Ericsson radio with an integrated omni antenna using the 5 GHz frequency band showed a compliance distance of less than 1’ for the general public for typical power levels.

Big Picture Around Cell Sites

Shut off switches Read the warning signs RF safety training if needed Personal RF safety

Monitoring Personal Exposure

Many monitors available. – Make sure they cover the

frequency band of interest and have a suitable dynamic range

– recommended instruments: RadManXT and Nardalert S3

(3 MHz to 40 GHz)– Field Sense 2.0 (50 MHz

to 6 GHz)

Regulatory Requirements for Small Cells?

Varies by jurisdiction My experience has been that cities and

counties that lack specific small cell regulations allow modification of the macro site rules for NIERs to a few worst case nodes

The exposure requirements for macro and small cell sites are exactly the same

Other carriers and 5G contribution in the future?

The need for 5GThe need for 5G

5G implementation is really about bandwidth to increase speed and lower latency

Fortunately, the higher frequencies where bandwidth is available can be re-used geographically with lesser concerns for interference

Unfortunately, attenuation as these higher frequencies is significant and problematic

What is 5G? What Frequencies are What is 5G? What Frequencies are Involved?Involved?

FCC makes changes to allow for millimeter wave (mmW) technology

Changes in rules to promote 3.5 GHz as a core frequency for 5G

Expand use in Mid-Band spectrum between 3.7 GHz and 24 GHz (3.7 – 4.2 GHz, 5.925-6.425 GHz, 6.425-7.125 GHz)

Additional 1700 MHz in 24 GHz and 47 GHz bands Allocations in 28 GHz, 37 GHz, and 39 GHz bands

•Auctioned a portion of the 600 MHz (UHF)•Includes licensed and unlicensed spectrum•NTIA has identified spectrum in 1.3, 1.7, 3.4 and 2.5 GHz band

•Opens up 150 MHz in 3.5 GHz band with 3 tier sharing 

•FCC improves priority licenses rules to allow for 5G

•FCC expands use in mid band spectrum 3.7 –4.2 GHz and 5.9‐7.1 GHz

•Some interest in opening up 3‐5 GHz spectrum for sharing

•In 2016, FCC opening up 11 GHz in multiple mmWavebands, 70% is shared or unlicensed

•In Nov 2017, allocated 24, 25, 28, 37, 39 and 48 GHz

•1700 MHz in 24 and 47 GHz bands alone

RF Exposures and Adverse Health EffectsWorker and General Public

Safety and Exposure Assessment

FCC OET 65

Which frequencies have RF thermal Which frequencies have RF thermal effects?effects?

Cellular & PCS frequencies

Regulatory Standards47 CFR 1.1310 Radiofrequency Radiation Exposure Limits

General Public / Uncontrolled Exposure (W/kg)

Occupational/ Controlled Exposure (W/kg)

Whole Body exposure

Whole Body Average 0.08 0.4

Localized exposure

Localized (peak spatial average) 1.6a 8a

Localized exposure

Extremities and pinnae 4b 20b

aAveraged over any 1 gram of tissuebAveraged of any 10 grams of tissue

Basis of StandardsBasis of Standards Current standards are designed to provide protection

to all age groups, including infants and children, on a continuous basis (24 hours/day, 7 days/week)*

Basis of standard is to prevent a thermoregulatory response which is at an absorption rate of 4 W/kg. A factor of 50 reduction from this rate serves as the basis for the general public.

Numerous expert reviews have affirmed the basis of this standard and no other adverse health effects have been identified.

*Direct quote from Health Canada press release March 13, 2015http://news.gc.ca/web/article-en.do?nid=949109

Standards Used in the WorldStandards Used in the World

International Commission of Non Ionizing Radiation Protection (ICNIRP) Guidelines (more than 60 countries)

Re-affirmed in 2009Argentina, Australia, Austria, Brazil, Colombia, Croatia, Czech Republic, Denmark, Ecuador, France, Finland, Germany, Hong Kong, Japan, Hungary, Ireland, Malaysia, Morocco, Netherlands, New Zealand, Norway, Oman, Pakistan, Paraguay, Peru, Philippines, Portugal, Romania, Rwanda, Saudi Arabia, Singapore, Slovak, Slovenia, South Africa, South Korea, Spain, Sweden, Thailand, Taiwan, Tanzania, Turkey, Uganda, UK, Venezuela, etc.

FCC Standard: Bolivia, Canada, Estonia, Panama, USA

Below ICNIRP and IEEEBelarus, Bulgaria, China, Lithuania, Poland, RussiaBelgium, Chile, Greece, India, Israel, Italy, Liechtenstein, Switzerland

In Vitro In Vitro StudiesStudies

Performed on biological systems such as cell cultures, tissue,etc. (test tube studies)

Important for determining possible mechanisms by which effects occur, aid in determining endpoints for animal studies

Can allow for study of interactions that may be masked in animal studies

Effects found in vitro must still be tested in vivo (in animal studies)

Studies to date are clear that RF exposure cannot initiate cancer.

In Vivo In Vivo Studies are:Studies are:

Conducted on laboratory animals. Advantageous as the studies can be

conducted under controlled conditions Are the results from a single type of animal

found in other animals as well? Some uncertainty in extrapolating results

from animal studies to humans

Literature EvaluationLiterature Evaluation

Recommendations in contemporary RF safety standards and guidelines (Basic Restrictions and Exposure Limits) are based on the following:

the results of comprehensive reviews and evaluations of the scientific literature (more than 1300 relevant citations in C95.1-2005) –

More than 6200 articles currently found onwww.emf-portal.org

findings of studies published mainly after 1950

studies that involve low level exposures (especially important)

conclusions supported by a lack of credible scientific and medical reports showing adverse health effects for RF exposures at or below similar exposure limits in past standards

Swedish Council: Ten Year Swedish Council: Ten Year Update (2012)Update (2012)

We now know much more about measurements and absorption of RF fields and also about sources of exposure to the population and levels of exposure. A considerable number of provocation studies on RF exposure and symptoms have been unable to show any association. Overall, the data on brain tumor and mobile telephony do not support an effect of mobile phone use on tumor risk, in particular when taken together with national cancer trend statistics throughout the world.

seer.cancer.gov/statfacts/html/brain.html

Swedish Radiation Safety Authority, 2015:

“In line with previous studies, new studies on adult and childhood cancer with improved exposure assessment do not indicate any health risks for the general public related to exposure from radiofrequency electromagnetic fields from far-field sources, such as base stations and radio and TV transmitters. There is no new evidence indicating a causal link to exposure from far-field sources such as mobile phone base stations or wireless local data networks in schools or at home.”[1]

1] Swedish Radiation Safety Authority. Tenth report from SSM’s Scientific Council on Electromagnetic Fields. 2015. http://www.stralsakerhetsmyndigheten.se/Global/Publikationer/Rapport/Stralskydd/2015/SSM-Rapport-2015-19.pdf

5G Exposure Effects5G Exposure Effects

Numerous reported biological effects as a result of mmWave exposure. mmWave is used in therapy in a range of applications.

No adverse effects not related to heating have been observed – but chronic studies are limited

Instances of hypersensitivity have been reported as a result of mmWave exposure

Aspects of 5G ExposureAspects of 5G Exposure Exposures at the occupational exposure limit

resulted in a skin temperature increase of 0.8°C Roughly 1/3 of the mmWave signal may be

reflected off the skin, all dependent on incident angle.

The wearing of clothing does affect absorption as clothing limits the ability of heat dissipation to the air

The use of MRIs can allow for detailed analysis of the heat absorption from mmWave exposure.

Relevant Scientific LiteratureRelevant Scientific Literature

Several thousand relevant RF bioeffect studies in the extant literature cover a wide range of frequencies and modulations

The literature database in of uneven quality

Absence of support for the “non-thermal hypothesis”

— Biophysical analyses and reviews do not provide convincing evidence that non-thermal interactions are plausible at RF frequencies

— Examination of biological effects literature does not provide a consistent body of data supporting theoretical postulates on “non-thermal” mechanisms

Expert Reviews

The IEEE International Committee on Electromagnetic Safety maintains an up to date list of recent reviews:

https://www.ices-emfsafety.org/expert-reviews/

Recent 5G StudiesRecent 5G Studies Exposures > 6 GHz have very shallow penetration limited to the

skin. Limits are related to incident power density as opposed to a SAR due to the limited penetration distance.

A number of articles are reviewing the models and results of mmW absorption:– Foster, KR. Ziskin, MC. and Balzano, Q. Thermal Response of

Human Skin to Microwave Energy: A Critical Review, Health Physics, 111(6): 528-541. 2016

– Foster, KR. Ziskin MC. and Balzano, Q. Thermal Modeling for the Next Generation of Radiofrequency Exposure Limits: Commentary. Health Physics, 113(1); 41-53, 2017.

– Ziskin, MC, Alekseev, SI, Foster KR, and Balzano, Q. Tissue Models for RF Exposure Evaluation at Frequecies above 6 GHz. Bioelectromagnetics, In Review.

– And others in review

– Aside: Expectations is that the current 8.4 Billion connected devices will grow by 10X in the next few years

What About LowWhat About Low--level RF Biological level RF Biological Effects?Effects?

Despite more than 60 years of RF research, there is no convincing evidence that supports low-level biological effects, i.e., effects that occur at exposure levels below the limits found in contemporary standards and guidelines No theoretical mechanism has been established

that supports the existence of any effect characterized by trivial heating other than microwave hearing The relevance of reported low-level biological

effects remains speculative and such effects are not useful for developing exposure limits

The study of the biological effects of RF energy is a mature scientific discipline with more than a 60 year history

The RF bioeffect literature database is extensive but of uneven quality

Scientists have been developing RF safety criteria based on critical evaluations and interpretations of the scientific literature for almost 60 years

Despite many thousands of studies that have been reported on allaspects of the subject since the first safety criteria were proposed, the exposure limits have not changed significantly

Changes in the exposure limits over the years have mainly resulted from a better understanding of the dosimetry

Both IEEE C95.1-2005 and ICNIRP guidelines are undergoing major revisions – estimated completion ~late 2018.

Final Thoughts