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Chung SI, Kang TW, Kim PK, Ha TG, Hong YP. Highly Transparent Ka-/W-Band Electromagnetic Shielding Films Based on Double-Layered Metal Meshes. ACS APPLIED MATERIALS & INTERFACES 2023; 15:56612-56622. [PMID: 37988133 DOI: 10.1021/acsami.3c14788] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
An electromagnetic (EM) wave-shielding film exhibiting high performance in high-frequency bands, such as the Ka- and W-bands, was fabricated by using double-layered metal meshes. The double-layered shielding (DLS) film consists of metallic micromesh and nanomesh electrodes (NMEs) on the upper and lower surfaces of a poly(ethylene terephthalate) (PET) film, respectively. The micromesh electrodes (MMEs) were fabricated such that they possessed a thickness higher than the line width, and they thus exhibited excellent electromagnetic wave-shielding performance in addition to optical transmittance. Moreover, the nanomesh electrodes helped prevent the deterioration of the shielding performance owing to the increase in frequency, which was possible by decreasing the aperture size of the mesh-type electrodes. The shielding effectiveness (SE) of the double-layered metal-mesh film was evaluated by using a shielding measurement system that is optimized for high frequencies. In addition, optical transmittance and flexibility tests were conducted. The results confirm that the double-layered shielding film exhibited a shielding effectiveness of more than 50 dB at an optical transmittance of 90% and a stable bending resistance of up to 5000 cycles at a radius of curvature of 6 mm. Double-layered metal-mesh films with such excellent performance are expected to be widely used in diverse applications such as the automobile, medical, and military industries.
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Affiliation(s)
- Sung-Il Chung
- Nano Hybrid Technology Research Center, Korea Electrotechnology Research Institute, Changwon 51543, Republic of Korea
| | - Tae-Weon Kang
- Electromagnetic Wave Metrology Group, Korea Research Institute of Standards and Science, Daejeon 34113, Republic of Korea
| | - Pan Kyeom Kim
- Nano Hybrid Technology Research Center, Korea Electrotechnology Research Institute, Changwon 51543, Republic of Korea
| | - Tae-Gyu Ha
- Nano Hybrid Technology Research Center, Korea Electrotechnology Research Institute, Changwon 51543, Republic of Korea
| | - Young-Pyo Hong
- Electromagnetic Wave Metrology Group, Korea Research Institute of Standards and Science, Daejeon 34113, Republic of Korea
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Hinrikus H, Koppel T, Lass J, Roosipuu P, Bachmann M. Limiting exposure to radiofrequency radiation: the principles and possible criteria for health protection. Int J Radiat Biol 2023; 99:1167-1177. [PMID: 36525560 DOI: 10.1080/09553002.2023.2159567] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 11/12/2022] [Accepted: 11/16/2022] [Indexed: 12/23/2022]
Abstract
PURPOSE The current paper is aimed to discuss the principles and criteria for health protection to radiofrequency electromagnetic field (RF EMF) considering both thermal and non-thermal mechanisms to evaluate the reasonable level for the limits relevant to control the level of RF EMF for the general public in the living environment. The study combines the conclusions of analyses published in recent reviews on RF EMF effects and the data from RF EMF measurements in different countries to select the possible criteria and to derive proposals for the health protection limits on the level of RF EMF following the ALARA principle - as low as reasonably achievable. CONCLUSIONS Consideration of not only energetic but also coherent qualities of RF EMF leads to two different models for determining the impact of non-ionizing radiation on human health. The thermal model, based on absorption of electromagnetic energy, has a threshold limiting the heating of tissues. The non-thermal model, based on the ability of coherent electric fields to introduce biological effects at constant temperature, has no threshold. Therefore, the impact of RF EMF on human health cannot be excluded but can be minimized by limiting the level of the radiation. The limits can be selected based on indirect criteria. The minimal level of RF EMF that has caused a biological effect is about 2 V/m. The level of long-term broadcast radiation is 6 V/m and the people can be assumed to be adapted to that level without observable health problems. The level of RF EMF measured during last years does not exceed 5 V/m and the level is decreasing with newer generations of telecommunication technology. Limiting the level of RF EMF to the peak value of 6 V/m hopefully reduces the health risk to a minimal level people are adapted to and does not restrict the further development of telecommunication technology.
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Affiliation(s)
- Hiie Hinrikus
- Department of Health Technologies, Tallinn University of Technology, Tallinn, Estonia
| | - Tarmo Koppel
- School of Business and Governance, Tallinn University of Technology, Tallinn, Estonia
| | - Jaanus Lass
- Department of Health Technologies, Tallinn University of Technology, Tallinn, Estonia
| | - Priit Roosipuu
- School of Information Technologies, Thomas Johann Seebeck Department of Electronics, Tallinn University of Technology, Tallinn, Estonia
| | - Maie Bachmann
- Department of Health Technologies, Tallinn University of Technology, Tallinn, Estonia
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Morimoto R, Hirata A. Assessment of incident power density in different shapes of averaging area for radio-frequency exposure above 6 GHz. Phys Med Biol 2022; 67. [DOI: 10.1088/1361-6560/ac994d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Accepted: 10/11/2022] [Indexed: 01/27/2023]
Abstract
Abstract
Objective. The International Commission on Non-Ionizing Radiation Protection guidelines and IEEE C95.1-2019 standard for human protection from local electromagnetic field exposure above 6 GHz state that absorbed (or epithelial) power density (APD) and incident power density (IPD), averaged over a square area, are internal and external physical quantities, respectively, that set the exposure limit. Per exposure standards, the measurement procedure and evaluation of the IPD have been established in technical standards, where a circular averaging area is recommended only for non-planar surfaces in IEC/IEEE 63195-1 and -2. In this study, the effects of two averaging shapes on the APD and IPD are evaluated computationally to provide new insights from the viewpoint of exposure standards. Approach. The relation between the APD, IPD, and the steady-state temperature rise (heating factor) in rectangular and human models for exposure to a single dipole, dipole arrays, and the Gaussian beams is investigated computationally with finite-difference method. Main results. The maximum differences in the heating factor of the APD and IPD for square and circular averaging areas were 4.1% and 4.4% for the antenna–model distance >5 mm, respectively. These differences appear when the beam pattern on the model surface has an elliptical shape. For an antenna–model distance ≤5 mm and at frequencies ≤15 GHz, the heating factors for square averaging areas were not always conservative to those for circular ones (−7.8% for IPD), where only the antenna feed point are visible before beam formation. Significance. The heating factors of the APD and IPD for a circular averaging area are conservative for near-field exposure of canonical sources for frequencies up to 300 GHz, except for a beam with a significant major-to-minor axis ratio and an angle of 30°–60° to a square averaging area. This tendency would help bridge the gap between exposure and product standards.
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Bonato M, Tognola G, Benini M, Gallucci S, Chiaramello E, Fiocchi S, Parazzini M. Assessment of SAR in Road-Users from 5G-V2X Vehicular Connectivity Based on Computational Simulations. SENSORS (BASEL, SWITZERLAND) 2022; 22:s22176564. [PMID: 36081025 PMCID: PMC9460500 DOI: 10.3390/s22176564] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 08/23/2022] [Accepted: 08/29/2022] [Indexed: 06/12/2023]
Abstract
(1) Background: Cooperative Intelligent Transportation Systems (C-ITS) will soon operate using 5G New-Radio (NR) wireless communication, overcoming the limitations of the current V2X (Vehicle-to-Everything) wireless communication technologies and increasing road-safety and driving efficiency. These innovations will also change the RF exposure levels of pedestrians and road-users in general. These people, in fact, will be exposed to additional RF sources coming from nearby cars and from the infrastructure. Therefore, an exposure assessment of people in the proximity of a connected car is necessary and urgent. (2) Methods: Two array antennas for 5G-V2X communication at 3.5 GHz were modelled and mounted on a realistic 3D car model for evaluating the exposure levels of a human model representing people on the road near the car. Computational simulations were conducted using the FDTD solver implemented in the Sim4Life platform; different positions and orientations between the car and the human model were assessed. The analyzed quantities were the Specific Absorption Rate on the whole body (SARwb), averaged over 10 g (SAR10g) in specific tissues, as indicated in the ICNIRP guidelines. (3) Results: the data showed that the highest exposure levels were obtained mostly in the head area of the human model, with the highest peak obtained in the configuration where the main beam of the 5G-V2X antennas was more direct towards the human model. Moreover, in all configurations, the dose absorbed by a pedestrian was well below the ICNIRP guidelines to avoid harmful effects. (4) Conclusions: This work is the first study on human exposure assessment in a 5G-V2X scenario, and it expands the knowledge about the exposure levels for the forthcoming use of 5G in connected vehicles.
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Affiliation(s)
- Marta Bonato
- Institute of Electronics, Computer and Telecommunication Engineering (IEIIT), CNR, 20133 Milano, Italy
| | - Gabriella Tognola
- Institute of Electronics, Computer and Telecommunication Engineering (IEIIT), CNR, 20133 Milano, Italy
| | - Martina Benini
- Institute of Electronics, Computer and Telecommunication Engineering (IEIIT), CNR, 20133 Milano, Italy
- Department of Electronics, Information and Bioengineering (DEIB), Politecnico di Milano, 20133 Milano, Italy
| | - Silvia Gallucci
- Institute of Electronics, Computer and Telecommunication Engineering (IEIIT), CNR, 20133 Milano, Italy
- Department of Electronics, Information and Bioengineering (DEIB), Politecnico di Milano, 20133 Milano, Italy
| | - Emma Chiaramello
- Institute of Electronics, Computer and Telecommunication Engineering (IEIIT), CNR, 20133 Milano, Italy
| | - Serena Fiocchi
- Institute of Electronics, Computer and Telecommunication Engineering (IEIIT), CNR, 20133 Milano, Italy
| | - Marta Parazzini
- Institute of Electronics, Computer and Telecommunication Engineering (IEIIT), CNR, 20133 Milano, Italy
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Sasaki K, Porter E, Rashed EA, Farrugia L, Schmid G. Measurement and image-based estimation of dielectric properties of biological tissues —past, present, and future—. Phys Med Biol 2022; 67. [DOI: 10.1088/1361-6560/ac7b64] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2022] [Accepted: 06/22/2022] [Indexed: 12/23/2022]
Abstract
Abstract
The dielectric properties of biological tissues are fundamental pararmeters that are essential for electromagnetic modeling of the human body. The primary database of dielectric properties compiled in 1996 on the basis of dielectric measurements at frequencies from 10 Hz to 20 GHz has attracted considerable attention in the research field of human protection from non-ionizing radiation. This review summarizes findings on the dielectric properties of biological tissues at frequencies up to 1 THz since the database was developed. Although the 1996 database covered general (normal) tissues, this review also covers malignant tissues that are of interest in the research field of medical applications. An intercomparison of dielectric properties based on reported data is presented for several tissue types. Dielectric properties derived from image-based estimation techniques developed as a result of recent advances in dielectric measurement are also included. Finally, research essential for future advances in human body modeling is discussed.
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Assessment of Human Exposure Levels Due to Mobile Phone Antennas in 5G Networks. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:ijerph19031546. [PMID: 35162566 PMCID: PMC8835459 DOI: 10.3390/ijerph19031546] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Revised: 01/25/2022] [Accepted: 01/28/2022] [Indexed: 02/05/2023]
Abstract
The recent deployment of 5G networks is bringing benefits to the population but it is also raising public concern about human RF-EMF exposure levels. This is particularly relevant considering the next 5G mobile devices, which are placed in close proximity to the subjects. Therefore, the aim of the following paper is focused on expanding the knowledge of the exposure levels in 5G exposure scenarios, specifically for mobile applications, using computational methods. The mobile antenna was designed considering the 5G technology innovations (i.e., mm-wave spectrum, beamforming capability, high gain and wide coverage), resulting in a phased-array antenna with eight elements at the working frequency of 27 GHz. To assess the exposure levels, different types of skin models with different grades of details and layers were considered. Furthermore, not only was the presence of a mobile phone user simulated, but also that of a person in their proximity, who could be hit by the main beam of the phased-array antenna. All the simulations were conducted in Sim4Life platform, where the exposure levels were assessed in terms of absorbed power density averaged over 4 cm2 and 1 cm2, following the ICNIRP guidelines. The results highlighted that the use of the homogeneous skin model led to the absorbed power density peaks being greatly underestimated, with respect to those obtained in multilayer skin models. Furthermore, interestingly, we found that the exposure levels obtained for the person passing nearby were slightly higher than those experienced by the mobile phone user himself. Finally, using the allowed input power for real mobile applications, all the values remained below the limits indicated by the ICNIRP guidelines.
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Cherkasova OP, Serdyukov DS, Nemova EF, Ratushnyak AS, Kucheryavenko AS, Dolganova IN, Xu G, Skorobogatiy M, Reshetov IV, Timashev PS, Spektor IE, Zaytsev KI, Tuchin VV. Cellular effects of terahertz waves. JOURNAL OF BIOMEDICAL OPTICS 2021; 26:JBO-210179VR. [PMID: 34595886 PMCID: PMC8483303 DOI: 10.1117/1.jbo.26.9.090902] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 09/08/2021] [Indexed: 05/15/2023]
Abstract
SIGNIFICANCE An increasing interest in the area of biological effects at exposure of tissues and cells to the terahertz (THz) radiation is driven by a rapid progress in THz biophotonics, observed during the past decades. Despite the attractiveness of THz technology for medical diagnosis and therapy, there is still quite limited knowledge about safe limits of THz exposure. Different modes of THz exposure of tissues and cells, including continuous-wave versus pulsed radiation, various powers, and number and duration of exposure cycles, ought to be systematically studied. AIM We provide an overview of recent research results in the area of biological effects at exposure of tissues and cells to THz waves. APPROACH We start with a brief overview of general features of the THz-wave-tissue interactions, as well as modern THz emitters, with an emphasis on those that are reliable for studying the biological effects of THz waves. Then, we consider three levels of biological system organization, at which the exposure effects are considered: (i) solutions of biological molecules; (ii) cultures of cells, individual cells, and cell structures; and (iii) entire organs or organisms; special attention is devoted to the cellular level. We distinguish thermal and nonthermal mechanisms of THz-wave-cell interactions and discuss a problem of adequate estimation of the THz biological effects' specificity. The problem of experimental data reproducibility, caused by rareness of the THz experimental setups and an absence of unitary protocols, is also considered. RESULTS The summarized data demonstrate the current stage of the research activity and knowledge about the THz exposure on living objects. CONCLUSIONS This review helps the biomedical optics community to summarize up-to-date knowledge in the area of cell exposure to THz radiation, and paves the ways for the development of THz safety standards and THz therapeutic applications.
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Affiliation(s)
- Olga P. Cherkasova
- Institute of Laser Physics of the Siberian Branch of the Russian Academy of Sciences, Russian Federation
- Novosibirsk State Technical University, Russian Federation
| | - Danil S. Serdyukov
- Institute of Laser Physics of the Siberian Branch of the Russian Academy of Sciences, Russian Federation
- Federal Research Center Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences, Russian Federation
| | - Eugenia F. Nemova
- Institute of Laser Physics of the Siberian Branch of the Russian Academy of Sciences, Russian Federation
| | - Alexander S. Ratushnyak
- Institute of Computational Technologies of the Siberian Branch of the Russian Academy of Sciences, Russian Federation
| | - Anna S. Kucheryavenko
- Institute of Solid State Physics of the Russian Academy of Sciences, Russian Federation
- Prokhorov General Physics Institute of the Russian Academy of Sciences, Russian Federation
| | - Irina N. Dolganova
- Institute of Solid State Physics of the Russian Academy of Sciences, Russian Federation
- Sechenov University, Institute for Regenerative Medicine, Russian Federation
- Sechenov University, World-Class Research Center “Digital Biodesign and Personalized Healthcare,” Russian Federation
| | - Guofu Xu
- Polytechnique Montreal, Department of Engineering Physics, Canada
| | | | - Igor V. Reshetov
- Sechenov University, Institute for Cluster Oncology, Russian Federation
- Academy of Postgraduate Education FSCC FMBA, Russian Federation
| | - Peter S. Timashev
- Sechenov University, Institute for Regenerative Medicine, Russian Federation
- Sechenov University, World-Class Research Center “Digital Biodesign and Personalized Healthcare,” Russian Federation
- N.N. Semenov Institute of Chemical Physics, Department of Polymers and Composites, Russian Federation
- Lomonosov Moscow State University, Department of Chemistry, Russian Federation
| | - Igor E. Spektor
- Prokhorov General Physics Institute of the Russian Academy of Sciences, Russian Federation
| | - Kirill I. Zaytsev
- Prokhorov General Physics Institute of the Russian Academy of Sciences, Russian Federation
- Sechenov University, Institute for Regenerative Medicine, Russian Federation
- Bauman Moscow State Technical University, Russian Federation
| | - Valery V. Tuchin
- Saratov State University, Russian Federation
- Institute of Precision Mechanics and Control of the Russian Academy of Sciences, Russian Federation
- National Research Tomsk State University, Russian Federation
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Foster KR, Ziskin MC, Balzano Q. Time-temperature Thresholds and Safety Factors for Thermal Hazards from Radiofrequency Energy above 6 GHz. HEALTH PHYSICS 2021; 121:234-247. [PMID: 34261892 PMCID: PMC8300848 DOI: 10.1097/hp.0000000000001447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
ABSTRACT Two major sets of exposure limits for radiofrequency (RF) radiation, those of the International Commission on Nonionizing Radiation Protection (ICNIRP 2020) and the Institute of Electrical and Electronics Engineers (IEEE C95.1-2019), have recently been revised and updated with significant changes in limits above 6 GHz through the millimeter wave (mm-wave) band (30-300 GHz). This review compares available data on thermal damage and pain from exposure to RF energy above 6 GHz with corresponding data from infrared energy and other heat sources and estimates safety factors that are incorporated in the IEEE and ICNIRP RF exposure limits. The benchmarks for damage are the same as used in ICNIRP IR limits: minimal epithelial damage to cornea and first-degree burn (erythema in skin observable within 48 h after exposure). The data suggest that limiting thermal hazard to skin is cutaneous pain for exposure durations less than ≈20 min and thermal damage for longer exposures. Limitations on available data and thermal models are noted. However, data on RF and IR thermal damage and pain thresholds show that exposures far above current ICNIRP and IEEE limits would be required to produce thermally hazardous effects. This review focuses exclusively on thermal hazards from RF exposures above 6 GHz to skin and the cornea, which are the most exposed tissues in the considered frequency range.
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Affiliation(s)
| | - Marvin C. Ziskin
- Department of Radiology, Temple University Medical School, 3420 N. Broad Street, Philadelphia, PA 19140
| | - Quirino Balzano
- Department of Electrical and Computer Engineering, University of Maryland, College Park, MD 20742
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Singh MM, Chandel P, Pati A, Parganiha A. Does exposure to radiofrequency radiation (RFR) affect the circadian rhythm of rest-activity patterns and behavioral sleep variables in humans? BIOL RHYTHM RES 2021. [DOI: 10.1080/09291016.2021.1945788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
| | - Priyanka Chandel
- School of Studies in Life Science, Pandit Ravishankar Shukla University, Raipur, India
| | - Atanu Pati
- School of Studies in Life Science, Pandit Ravishankar Shukla University, Raipur, India
- Center for Translational Chronobiology, Pandit Ravishankar Shukla University, Raipur, India
- Department of Zoology, Gangadhar Meher University, Sambalpur, India
| | - Arti Parganiha
- School of Studies in Life Science, Pandit Ravishankar Shukla University, Raipur, India
- Center for Translational Chronobiology, Pandit Ravishankar Shukla University, Raipur, India
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10
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Gajda GB, Paradis J, Lemay E. Steady state temperature rise in multilayered tissue due to arbitrary periodic SAR using finite difference FFT and transfer function method. Biomed Phys Eng Express 2021; 7. [PMID: 34077918 DOI: 10.1088/2057-1976/ac0779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 06/02/2021] [Indexed: 11/12/2022]
Abstract
Steady state (SS) and transient temperature-rise in tissue from radiofrequency exposure forms the underlying basis for limits in international exposure guidelines. Periodically pulsed or intermittent exposures form a special case of having both peak and average levels, producing temperature-rise oscillations in the SS. Presented here is a method for determining tissue temperature-rise for periodic specific absorption rate (SAR) modulation having arbitrary waveform. It involves the finite difference solution of a form of the Pennes Bioheat Transfer equation (BHTE) and uses the concept of the transfer function and the Fast Fourier Transform (FFT). The time-dependent BHTE is converted to a SS harmonic version by assuming that the time-dependent SAR waveform and tissue temperature can both be represented by Fourier series. The transfer function is obtained from solutions of the harmonic BHTE for an assumed SAR waveform consisting of periodic impulses. The temperature versus time response for an arbitrary periodic SAR waveform is obtained from the inverse FFT of the product of the transfer function and the FFT of the actual SAR waveform. This method takes advantage of existing FFT algorithms on most computational platforms and the ability to store the transfer function for later re-use. The transfer function varies slowly with harmonic number, allowing interpolation and extrapolation to reduce the computational effort. The method is highly efficient for the case where repeated temperature-rise calculations for parameter variations in the SAR waveform are sought. Examples are given for a narrow, circularly symmetric beam incident on a planar skin/fat/muscle model with rectangular, triangular and cosine-pulsed SAR modulation waveforms. Calculations of temperature-rise crest factor as a function of rectangular pulse duty factor and pulse repetition frequency for the same exposure/tissue model are also presented as an example of the versatility of the method.
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Affiliation(s)
- Gregory B Gajda
- Non-ionizing Radiation Physical Sciences Division, Consumer and Clinical Radiation Protection Bureau, Health Canada, 775 Brookfield Rd., Ottawa, Ontario, K1A 1C1, Canada
| | - Jonathan Paradis
- Non-ionizing Radiation Physical Sciences Division, Consumer and Clinical Radiation Protection Bureau, Health Canada, 775 Brookfield Rd., Ottawa, Ontario, K1A 1C1, Canada
| | - Eric Lemay
- Non-ionizing Radiation Physical Sciences Division, Consumer and Clinical Radiation Protection Bureau, Health Canada, 775 Brookfield Rd., Ottawa, Ontario, K1A 1C1, Canada
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Foster KR, Laakso I, Chalfin S. Nonuniform Exposure to the Cornea from Millimeter Waves. HEALTH PHYSICS 2021; 120:525-531. [PMID: 33760769 DOI: 10.1097/hp.0000000000001376] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
This study examines the nonuniform exposure to the cornea from incident millimeter waves at 94-100 GHz. Two previous studies measured temperature increases in the rhesus cornea exposed to brief (1-6 s) pulses of high-fluence millimeter waves (94 GHz), one of which also estimated thresholds for corneal damage (reported as ED50, the dose resulting in a visible lesion 50% of the time). Both studies noted large variations in the temperature increase across the surface of the cornea due to wave interference effects. This study examines this variability using high-resolution simulations of mm-wave absorption and temperature increase in the human cornea from exposures to plane wave energy at 100 GHz. Calculations are based on an earlier study. The simulations show that the peak temperature increases in the cornea from short exposures (up to 10 s) to high-intensity mm-wave pulses are 1.7-2.8 times the median increase depending on the polarization of the incident energy. A simple one-dimensional "baseline" model provides a good estimate of the median temperature increase in the cornea. Two different estimates are presented for the thresholds for producing thermal lesions, expressed in terms of the minimum fluence of incident 100 GHz pulses. The first estimate is based on thresholds for thermal damage from pulsed infrared energy, and the second is based on a thermal damage model. The mm-wave pulses presently considered far exceed current IEEE or ICNIRP exposure limits but may be produced by some nonlethal weapons systems. Interference effects due to wave reflections from structures in and near the eye result in highly localized variations in energy absorbed in the cornea and surrounding facial tissues and are important to consider in a hazard analysis for exposures to intense pulsed millimeter waves.
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Affiliation(s)
- Kenneth R Foster
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19106
| | - Ilkka Laakso
- Department of Electrical Engineering and Automation, Aalto University, Espoo, Finland
| | - Steven Chalfin
- Ophthalmology Department, University of Texas Health Science Center, San Antonio, TX 78229
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Hirata A, Kodera S, Sasaki K, Gomez-Tames J, Laakso I, Wood A, Watanabe S, Foster KR. Human exposure to radiofrequency energy above 6 GHz: review of computational dosimetry studies. Phys Med Biol 2021; 66. [PMID: 33761473 DOI: 10.1088/1361-6560/abf1b7] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Accepted: 03/24/2021] [Indexed: 11/11/2022]
Abstract
International guidelines/standards for human protection from electromagnetic fields have been revised recently, especially for frequencies above 6 GHz where new wireless communication systems have been deployed. Above this frequency a new physical quantity 'absorbed/epithelial power density' has been adopted as a dose metric. Then, the permissible level of external field strength/power density is derived for practical assessment. In addition, a new physical quantity, fluence or absorbed energy density, is introduced for protection from brief pulses (especially for shorter than 10 s). These limits were explicitly designed to avoid excessive increases in tissue temperature, based on electromagnetic and thermal modeling studies but supported by experimental data where available. This paper reviews the studies on the computational modeling/dosimetry which are related to the revision of the guidelines/standards. The comparisons with experimental data as well as an analytic solution are also been presented. Future research needs and additional comments on the revision will also be mentioned.
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Affiliation(s)
- Akimasa Hirata
- Dept. of Electrical and Mechanical Engineering, Nagoya Institute of Technology, Nagoya, Japan.,Center of Biomedical Physics and Information Technology, Nagoya Institute of Technology, Nagoya Japan
| | - Sachiko Kodera
- Dept. of Electrical and Mechanical Engineering, Nagoya Institute of Technology, Nagoya, Japan
| | - Kensuke Sasaki
- National Institute of Information and Communications Technology, Tokyo, Japan
| | - Jose Gomez-Tames
- Dept. of Electrical and Mechanical Engineering, Nagoya Institute of Technology, Nagoya, Japan.,Center of Biomedical Physics and Information Technology, Nagoya Institute of Technology, Nagoya Japan
| | - Ilkka Laakso
- Dept. of Electrical Engineering and Automation, Aalto University, Espoo, Finland
| | - Andrew Wood
- Swinburne University of Technology Melbourne, Melbourne, Australia
| | - Soichi Watanabe
- National Institute of Information and Communications Technology, Tokyo, Japan
| | - Kenneth R Foster
- University of Pennsylvania, Philadelphia, PA, United States of America
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13
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Bushberg JT, Chou CK, Foster KR, Kavet R, Maxson DP, Tell RA, Ziskin MC. IEEE Committee on Man and Radiation-COMAR Technical Information Statement: Health and Safety Issues Concerning Exposure of the General Public to Electromagnetic Energy from 5G Wireless Communications Networks. HEALTH PHYSICS 2020; 119:236-246. [PMID: 32576739 PMCID: PMC7337122 DOI: 10.1097/hp.0000000000001301] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Accepted: 04/18/2020] [Indexed: 06/11/2023]
Abstract
This COMAR Technical Information Statement (TIS) addresses health and safety issues concerning exposure of the general public to radiofrequency (RF) fields from 5G wireless communications networks, the expansion of which started on a large scale in 2018 to 2019. 5G technology can transmit much greater amounts of data at much higher speeds for a vastly expanded array of applications compared with preceding 2-4G systems; this is due, in part, to using the greater bandwidth available at much higher frequencies than those used by most existing networks. Although the 5G engineering standard may be deployed for operating networks currently using frequencies extending from 100s to 1,000s of MHz, it can also operate in the 10s of GHz where the wavelengths are 10 mm or less, the so-called millimeter wave (MMW) band. Until now, such fields were found in a limited number of applications (e.g., airport scanners, automotive collision avoidance systems, perimeter surveillance radar), but the rapid expansion of 5G will produce a more ubiquitous presence of MMW in the environment. While some 5G signals will originate from small antennas placed on existing base stations, most will be deployed with some key differences relative to typical transmissions from 2-4G base stations. Because MMW do not penetrate foliage and building materials as well as signals at lower frequencies, the networks will require "densification," the installation of many lower power transmitters (often called "small cells" located mainly on buildings and utility poles) to provide for effective indoor coverage. Also, "beamforming" antennas on some 5G systems will transmit one or more signals directed to individual users as they move about, thus limiting exposures to non-users. In this paper, COMAR notes the following perspectives to address concerns expressed about possible health effects of RF field exposure from 5G technology. First, unlike lower frequency fields, MMW do not penetrate beyond the outer skin layers and thus do not expose inner tissues to MMW. Second, current research indicates that overall levels of exposure to RF are unlikely to be significantly altered by 5G, and exposure will continue to originate mostly from the "uplink" signals from one's own device (as they do now). Third, exposure levels in publicly accessible spaces will remain well below exposure limits established by international guideline and standard setting organizations, including ICNIRP and IEEE. Finally, so long as exposures remain below established guidelines, the research results to date do not support a determination that adverse health effects are associated with RF exposures, including those from 5G systems. While it is acknowledged that the scientific literature on MMW biological effect research is more limited than that for lower frequencies, we also note that it is of mixed quality and stress that future research should use appropriate precautions to enhance validity. The authorship of this paper includes a physician/biologist, epidemiologist, engineers, and physical scientists working voluntarily and collaboratively on a consensus basis.
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Affiliation(s)
- J T Bushberg
- Committee on Man and Radiation (COMAR), IEEE Engineering in Medicine and Biology Society
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Christ A, Samaras T, Neufeld E, Kuster N. RF-INDUCED TEMPERATURE INCREASE IN A STRATIFIED MODEL OF THE SKIN FOR PLANE-WAVE EXPOSURE AT 6-100 GHZ. RADIATION PROTECTION DOSIMETRY 2020; 188:350-360. [PMID: 31950182 DOI: 10.1093/rpd/ncz293] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 11/11/2019] [Accepted: 11/21/2019] [Indexed: 06/10/2023]
Abstract
This study assesses the maximum temperature increase induced by exposure to electromagnetic fields between 6 and 100 GHz using a stratified model of the skin with four or five layers under plane wave incidence. The skin model distinguishes the stratum corneum (SC) and the viable epidermis as the outermost layers of the skin. The analysis identifies the tissue layer structures that minimize reflection and maximize the temperature increase induced by the electromagnetic field. The maximum observed temperature increase is 0.4°C for exposure at the present power density limit for the general population of 10 W m -2 . This result is more than twice as high as the findings reported in a previous study. The reasons for this difference are identified as impedance matching effects in the SC and less conservative thermal parameters. Modeling the skin as homogeneous dermis tissue can underestimate the induced temperature increase by more than a factor of three.
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Affiliation(s)
| | - Theodoros Samaras
- Department of Physics, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | | | - Niels Kuster
- IT'IS Foundation, Zürich, Switzerland
- Swiss Federal Institute of Technology (ETHZ), Zürich, Switzerland
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15
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Christ A, Samaras T, Neufeld E, Kuster N. Limitations of Incident Power Density as a Proxy for Induced Electromagnetic Fields. Bioelectromagnetics 2020; 41:348-359. [DOI: 10.1002/bem.22268] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 04/06/2020] [Accepted: 04/22/2020] [Indexed: 11/06/2022]
Affiliation(s)
| | - Theodoros Samaras
- Department of PhysicsAristotle University of ThessalonikiThessaloniki Greece
| | | | - Niels Kuster
- IT'IS FoundationZürich Switzerland
- Swiss Federal Institute of TechnologyZürich Switzerland
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Abstract
Radiofrequency electromagnetic fields (EMFs) are used to enable a number of modern devices, including mobile telecommunications infrastructure and phones, Wi-Fi, and Bluetooth. As radiofrequency EMFs at sufficiently high power levels can adversely affect health, ICNIRP published Guidelines in 1998 for human exposure to time-varying EMFs up to 300 GHz, which included the radiofrequency EMF spectrum. Since that time, there has been a considerable body of science further addressing the relation between radiofrequency EMFs and adverse health outcomes, as well as significant developments in the technologies that use radiofrequency EMFs. Accordingly, ICNIRP has updated the radiofrequency EMF part of the 1998 Guidelines. This document presents these revised Guidelines, which provide protection for humans from exposure to EMFs from 100 kHz to 300 GHz.
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Simkó M, Mattsson MO. 5G Wireless Communication and Health Effects-A Pragmatic Review Based on Available Studies Regarding 6 to 100 GHz. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2019; 16:E3406. [PMID: 31540320 PMCID: PMC6765906 DOI: 10.3390/ijerph16183406] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Revised: 09/09/2019] [Accepted: 09/11/2019] [Indexed: 02/07/2023]
Abstract
The introduction of the fifth generation (5G) of wireless communication will increase the number of high-frequency-powered base stations and other devices. The question is if such higher frequencies (in this review, 6-100 GHz, millimeter waves, MMW) can have a health impact. This review analyzed 94 relevant publications performing in vivo or in vitro investigations. Each study was characterized for: study type (in vivo, in vitro), biological material (species, cell type, etc.), biological endpoint, exposure (frequency, exposure duration, power density), results, and certain quality criteria. Eighty percent of the in vivo studies showed responses to exposure, while 58% of the in vitro studies demonstrated effects. The responses affected all biological endpoints studied. There was no consistent relationship between power density, exposure duration, or frequency, and exposure effects. The available studies do not provide adequate and sufficient information for a meaningful safety assessment, or for the question about non-thermal effects. There is a need for research regarding local heat developments on small surfaces, e.g., skin or the eye, and on any environmental impact. Our quality analysis shows that for future studies to be useful for safety assessment, design and implementation need to be significantly improved.
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Affiliation(s)
- Myrtill Simkó
- SciProof International AB, Vaktpoststigen 4, 83132 Östersund, Sweden.
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Reinišová L, Hermanová S, Pumera M. Micro/nanomachines: what is needed for them to become a real force in cancer therapy? NANOSCALE 2019; 11:6519-6532. [PMID: 30632584 DOI: 10.1039/c8nr08022d] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Conventional drug delivery systems face several issues in medical applications, such as cyto/genotoxicity and off-targeting. These issues are particularly significant for cancer therapeutics because many of the currently used systems are toxic in their free form. Self-propelled autonomous micro/nanomachines offer promising alternative drug delivery systems based on high cargo loading, fast autonomous movement, precise targeting and the on-demand release of therapeutics in vivo. With this unique set of properties, it is not surprising that they are receiving considerable research attention. However, much less is reported about the drawbacks that hinder their systemic in vivo application. In this review, a biomedical perspective is used to assess micro/nanomotor-based anticancer drug delivery systems reported to date. Advantages along with present issues are highlighted and recommendations which need to be considered to develop an effective biocompatible micro/nanomotor-based delivery system for cancer therapy are discussed.
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Affiliation(s)
- Lucie Reinišová
- Department of Polymers, Faculty of Chemical Technology, University of Chemistry and Technology Prague, Technická 5, 16628 Prague, Czech Republic
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Neufeld E, Kuster N. Systematic Derivation of Safety Limits for Time-Varying 5G Radiofrequency Exposure Based on Analytical Models and Thermal Dose. HEALTH PHYSICS 2018; 115:705-711. [PMID: 30247338 DOI: 10.1097/hp.0000000000000930] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Extreme broadband wireless devices operating above 10 GHz may transmit data in bursts of a few milliseconds to seconds. Even though the time- and area-averaged power density values remain within the acceptable safety limits for continuous exposure, these bursts may lead to short temperature spikes in the skin of exposed people. In this paper, a novel analytical approach to pulsed heating is developed and applied to assess the peak-to-average temperature ratio as a function of the pulse fraction α (relative to the averaging time [INCREMENT]T; it corresponds to the inverse of the peak-to-average ratio). This has been analyzed for two different perfusion-related thermal time constants (τ1 = 100 s and 500 s) corresponding to plane-wave and localized exposures. To allow for peak temperatures that considerably exceed the 1 K increase, the CEM43 tissue damage model, with an experimental-data-based damage threshold for human skin of 600 min, is used to allow large temperature oscillations that remain below the level at which tissue damage occurs. To stay consistent with the current safety guidelines, safety factors of 10 for occupational exposure and 50 for the general public were applied. The model assumptions and limitations (e.g., employed thermal and tissue damage models, homogeneous skin, consideration of localized exposure by a modified time constant) are discussed in detail. The results demonstrate that the maximum averaging time, based on the assumption of a thermal time constant of 100 s, is 240 s if the maximum local temperature increase for continuous-wave exposure is limited to 1 K and α ≥ 0.1. For a very low peak-to-average ratio of 100 (α ≥ 0.01), it decreases to only 30 s. The results also show that the peak-to-average ratio of 1,000 tolerated by the International Council on Non-Ionizing Radiation Protection guidelines may lead to permanent tissue damage after even short exposures, highlighting the importance of revisiting existing exposure guidelines.
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Affiliation(s)
- Esra Neufeld
- 1Foundation for Research on Information Technologies in Society (IT'IS), Zeughausstrasse 43, 8004 Zurich, Switzerland; 2Swiss Federal Institute of Technology (ETH) Zurich, 8092 Zurich, Switzerland
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