Electromagnetic radiation and health
At sufficiently high flux levels, various bands of electromagnetic radiation have been found to cause deleterious health effects in people. Electromagnetic radiation can be classified into two types: ionizing radiation and non-ionizing radiation, based on the capability of a single photon with more than 10 eV energy to ionize oxygen or break chemical bonds. Extreme ultraviolet and higher frequencies, such as X-rays or gamma rays are ionizing, and these pose their own special hazards: see radiation and radiation poisoning. The last quarter of the twentieth century saw a dramatic increase in the number of devices emitting non-ionizing radiation in all segments of society, which resulted in an elevation of health concerns by researchers and clinicians, and an associated interest in government regulation for safety purposes. In the United States, this has resulted in legislation such as the Radiation Control for Health and Safety Act of 1968 and the Occupational Safety and Health Act of 1970. By far the most common health hazard of radiation is sunburn, which causes over one million new skin cancers annually in United States.
Sufficiently strong electromagnetic radiation (EMR) can cause electric currents in conductive materials that is strong enough to create sparks (electrical arcs) when an induced voltage exceeds the breakdown voltage of the surrounding medium (e.g. air at 3.0 MV/m). These can deliver an electric shock to persons or animals. For example, the radio emissions from transmission lines have occasionally caused shocks to construction workers from nearby equipment, causing OSHA to establish standards for proper handling.
EMR-induced sparks can ignite nearby flammable materials or gases, which can be especially hazardous in the vicinity of explosives or pyrotechnics. This risk is commonly referred to as Hazards of Electromagnetic Radiation to Ordnance (HERO) by the United States Navy (USN). United States Military Standard 464A (MIL-STD-464A) mandates assessment of HERO in a system, but USN document OD 30393 provides design principles and practices for controlling electromagnetic hazards to ordnance. The risk related to fueling is known as Hazards of Electromagnetic Radiation to Fuel (HERF). NAVSEA OP 3565 Vol. 1 could be used to evaluate HERF, which states a maximum power density of 0.09 W/m² for frequencies under 225 MHz (i.e. 4.2 meters for a 40 W emitter).
Dielectric heating from electromagnetic fields can create a biological hazard. For example, touching or standing around an antenna while a high-power transmitter is in operation can cause severe burns. These are exactly the kind of burns that would be caused inside a microwave oven. The dialectric heating effect varies with the power and the frequency of the electromagnetic energy, as well as the distance to the source. The eyes and testes are particularly susceptible to radio frequency heating due to the paucity of blood flow in these areas that could otherwise dissipate the heat buildup.
Radio frequency (RF) energy at power density levels of 1-10 mW/cm2 or higher can cause measurable heating of tissues. Typical RF energy levels encountered by the general public are well below the level needed to cause significant heating, but certain workplace environments near high power RF sources may exceed safe exposure limits. A measure of the heating effect is the specific absorption rate or SAR, which has units of watts per kilogram (W/kg). The IEEE and many national governments have established safety limits for exposure to various frequencies of electromagnetic energy based on SAR, mainly based on ICNIRP Guidelines, which guard against thermal damage.
The World Health Organization began a research effort in 1996 to study the health effects from the ever-increasing exposure of people to a diverse range of EMR sources. After 30 years of extensive study, science has yet to confirm a health risk from exposure to low-level fields. However, there remain gaps in the understanding of the biological effects, and more research needs to be performed. Studies are being run to examine cells and determine if EM exposure can cause detrimental effects. Animal studies are being used to look for effects impacting more complex physiologies that are similar to humans. Epidemiological studies look for statistical correlations between EM exposure in the field and specific health effects. As of 2019, much of the current work is focused on the study of EM fields in relation to cancer.
There are publications which support the existence of complex biological and neurological effects of weaker non-thermal electromagnetic fields (see Bioelectromagnetics), including weak ELF electromagnetic fields and modulated RF and microwave fields. Fundamental mechanisms of the interaction between biological material and electromagnetic fields at non-thermal levels are not fully understood.
Effects by frequency
While the most acute exposures to harmful levels of electromagnetic radiation are immediately realized as burns, the health effects due to chronic or occupational exposure may not manifest effects for months or years.
High-power, extremely-low-frequency RF with electric field levels in the low kV/m range are known to induce perceivable currents within the human body that create an annoying tingling sensation. These currents will typically flow to ground through a body contact surface such as the feet, or arc to ground where the body is well insulated.
Shortwave (1.6 to 30 MHz) diathermy can be used as a therapeutic technique for its analgesic effect and deep muscle relaxation, but has largely been replaced by ultrasound. Temperatures in muscles can increase by 4–6 °C, and subcutaneous fat by 15 °C. The FCC has restricted the frequencies allowed for medical treatment, and most machines in the US use 27.12 MHz. Shortwave diathermy can be applied in either continuous or pulsed mode. The latter came to prominence because the continuous mode produced too much heating too rapidly, making patients uncomfortable. The technique only heats tissues that are good electrical conductors, such as blood vessels and muscle. Adipose tissue (fat) receives little heating by induction fields because an electrical current is not actually going through the tissues.
Studies have been performed on the use of shortwave radiation for cancer therapy and promoting wound healing, with some success. However, at a sufficiently high energy level, shortwave energy can be harmful to human health, potentially causing damage to biological tissues. The FCC limits for maximum permissible workplace exposure to shortwave radio frequency energy in the range of 3–30 MHz has a plane-wave equivalent power density of (900/f2) mW/cm2 where f is the frequency in MHz, and 100 mW/cm2 from 0.3–3.0 MHz. For uncontrolled exposure to the general public, the limit is 180/f2 between 1.34–30 MHz.
Radio frequency field
The designation of mobile phone signals as "possibly carcinogenic to humans" by the World Health Organization (WHO) (e.g. its IARC, see below) has often been misinterpreted as indicating that some measure of risk has been observed – however the designation indicates only that the possibility could not be conclusively ruled out using the available data.
In 2011, International Agency for Research on Cancer (IARC) classified mobile phone radiation as Group 2B "possibly carcinogenic" (rather than Group 2A "probably carcinogenic" nor the "is carcinogenic" Group 1). That means that there "could be some risk" of carcinogenicity, so additional research into the long-term, heavy use of mobile phones needs to be conducted. The WHO concluded in 2014 that "A large number of studies have been performed over the last two decades to assess whether mobile phones pose a potential health risk. To date, no adverse health effects have been established as being caused by mobile phone use."
Since 1962, the microwave auditory effect or tinnitus has been shown from radio frequency exposure at levels below significant heating. Studies during the 1960s in Europe and Russia claimed to show effects on humans, especially the nervous system, from low energy RF radiation; the studies were disputed at the time.:427–30
In 2019 reporters from The Chicago Tribune tested the level of radiation from smartphones and found that it exceed the safe level. The federal communications commission begun to check the findings.
Recent technology advances in the developments of millimeter wave scanners for airport security and WiGig for personal area networks have opened the 60 GHz and above microwave band to SAR exposure regulations. Previously, microwave applications in these bands were for point-to-point satellite communication with minimal human exposure.[relevant? ]
Infrared wavelengths longer than 750 nm can produce changes in the lens of the eye. Glassblower's cataract is an example of a heat injury that damages the anterior lens capsule among unprotected glass and iron workers. Cataract-like changes can occur in workers who observe glowing masses of glass or iron without protective eyewear for prolonged periods over many years.
Another important factor is the distance between the worker and the source of radiation. In the case of arc welding, infrared radiation decreases rapidly as a function of distance, so that farther than three feet away from where welding takes place, it does not pose an ocular hazard anymore but, ultraviolet radiation still does. This is why welders wear tinted glasses and surrounding workers only have to wear clear ones that filter UV.
Photic retinopathy is damage to the macular area of the eye's retina that results from prolonged exposure to sunlight, particularly with dilated pupils. This can happen, for example, while observing a solar eclipse without suitable eye protection. The Sun's radiation creates a photochemical reaction that can result in visual dazzling and a scotoma. The initial lesions and edema will disappear after several weeks, but may leave behind a permanent reduction in visual acuity.
Moderate and high-power lasers are potentially hazardous because they can burn the retina of the eye, or even the skin. To control the risk of injury, various specifications – for example ANSI Z136 in the US, EN 60825-1/A2 in Europe, and IEC 60825 internationally – define "classes" of lasers depending on their power and wavelength. Regulations prescribe required safety measures, such as labeling lasers with specific warnings, and wearing laser safety goggles during operation (see laser safety).
As with its infrared and ultraviolet radiation dangers, welding creates an intense brightness in the visible light spectrum, which may cause temporary flash blindness. Some sources state that there is no minimum safe distance for exposure to these radiation emissions without adequate eye protection.
Sunlight includes sufficient ultraviolet power to cause sunburn within hours of exposure, and the burn severity increases with the duration of exposure. This effect is a response of the skin called erythema, which is caused by a sufficient strong dose of UV-B. The Sun's UV output is divided into UV-A and UV-B: solar UV-A flux is 100 times that of UV-B, but the erythema response is 1,000 times higher for UV-B. This exposure can increase at higher altitudes and when reflected by snow, ice, or sand. The UV-B flux is 2–4 times greater during the middle 4–6 hours of the day, and is not significantly absorbed by cloud cover or up to a meter of water.
Ultraviolet light, specifically UV-B, has been shown to cause cataracts and there is some evidence that sunglasses worn at an early age can slow its development in later life. Most UV light from the sun is filtered out by the atmosphere and consequently airline pilots often have high rates of cataracts because of the increased levels of UV radiation in the upper atmosphere. It is hypothesized that depletion of the ozone layer and a consequent increase in levels of UV light on the ground may increase future rates of cataracts. Note that the lens filters UV light, so if it is removed via surgery, one may be able to see UV light.
Prolonged exposure to ultraviolet radiation from the sun can lead to melanoma and other skin malignancies. Clear evidence establishes ultraviolet radiation, especially the non-ionizing medium wave UVB, as the cause of most non-melanoma skin cancers, which are the most common forms of cancer in the world. UV rays can also cause wrinkles, liver spots, moles, and freckles. In addition to sunlight, other sources include tanning beds, and bright desk lights. Damage is cumulative over one's lifetime, so that permanent effects may not be evident for some time after exposure.
Ultraviolet radiation of wavelengths shorter than 300 nm (actinic rays) can damage the corneal epithelium. This is most commonly the result of exposure to the sun at high altitude, and in areas where shorter wavelengths are readily reflected from bright surfaces, such as snow, water, and sand. UV generated by a welding arc can similarly cause damage to the cornea, known as "arc eye" or welding flash burn, a form of photokeratitis.
Fluorescent light bulbs and tubes internally produce ultraviolet light. Normally this is converted to visible light by the phosphor film inside a protective coating. When the film is cracked by mishandling or faulty manufacturing then UV may escape at levels that could cause sunburn or even skin cancer.
- Background radiation
- BioInitiative Report
- Biological effects of radiation on the epigenome
- Central nervous system effects from radiation exposure during spaceflight
- Cosmic ray
- COSMOS cohort study
- Electromagnetic hypersensitivity
- EMF measurements
- Health threat from cosmic rays
- Light ergonomics
- Mobile phone radiation and health
- Personal RF safety monitors
- Specific absorption rate
- Wireless electronic devices and health
- Cleveland, Jr., Robert F.; Ulcek, Jerry L. (August 1999). Questions and Answers about Biological Effects and Potential Hazards of Radiofrequency Electromagnetic Fields (PDF) (4th ed.). Washington, D.C.: OET (Office of Engineering and Technology) Federal Communications Commission. Retrieved 29 January 2019.
- Michaelson, Solomon, ed. (2012). Fundamental and Applied Aspects of Nonionizing Radiation. Springer Science & Business Media. p. xv. ISBN 9781468407600.
- Cleaver JE, Mitchell DL (2000). "15. Ultraviolet Radiation Carcinogenesis". In Bast RC, Kufe DW, Pollock RE, et al. (eds.). Holland-Frei Cancer Medicine (5th ed.). Hamilton, Ontario: B.C. Decker. ISBN 1-55009-113-1. Retrieved 31 January 2011.
- Britton, Laurence G. (2010). Avoiding Static Ignition Hazards in Chemical Operations. A CCPS Concept Book. 20. John Wiley & Sons. p. 247. ISBN 9780470935392.
- "Radiofrequency Energy Poses Unseen Hazard". EHS Today. Informa USA, Inc. 11 December 2002. Retrieved 3 February 2019.
- Barnes, Frank S.; Greenebaum, Ben, eds. (2018). Biological and Medical Aspects of Electromagnetic Fields (3 ed.). CRC Press. p. 378. ISBN 9781420009460.
- Cleveland, Jr., Robert F.; Ulcek, Jerry L. (August 1999). "Questions and Answers about Biological Effects and Potential Hazards of Radiofrequency Electromagnetic Fields" (PDF). OET Bulletin 56 (Fourth ed.). Office of Engineering and Technology, Federal Communications Commission. p. 7. Retrieved 2 February 2019.
- "Standard for Safety Level with Respect to Human Exposure to Radio Frequency Electromagnetic Fields, 3KHz to 300GHz". IEEE STD. IEEE. C95.1-2005. October 2005.
- International Commission on Non-Ionizing Radiation Protection (April 1998). "Guidelines for limiting exposure to time-varying electric, magnetic, and electromagnetic fields (up to 300 GHz)" (PDF). Health Physics. 74 (4): 494–522. PMID 9525427. Archived from the original (PDF) on 13 November 2008.
- "What are electromagnetic fields? – Summary of health effects". World Health Organization. Retrieved 7 February 2019.
- Delgado JM, Leal J, Monteagudo JL, Gracia MG (May 1982). "Embryological changes induced by weak, extremely low frequency electromagnetic fields". Journal of Anatomy. 134 (3): 533–51. PMC 1167891. PMID 7107514.
- Harland JD, Liburdy RP (1997). "Environmental magnetic fields inhibit the antiproliferative action of tamoxifen and melatonin in a human breast cancer cell line". Bioelectromagnetics. 18 (8): 555–62. doi:10.1002/(SICI)1521-186X(1997)18:8<555::AID-BEM4>3.0.CO;2-1. PMID 9383244.
- Aalto S, Haarala C, Brück A, Sipilä H, Hämäläinen H, Rinne JO (July 2006). "Mobile phone affects cerebral blood flow in humans". Journal of Cerebral Blood Flow and Metabolism. 26 (7): 885–90. doi:10.1038/sj.jcbfm.9600279. PMID 16495939.
- Pal, Martin (2016). "Microwave frequency electromagnetic fields (EMFs) produce widespread neuropsychiatric effects including depression". Journal of Chemical Neuroanatomy. 75 (Pt B): 43–51. doi:10.1016/j.jchemneu.2015.08.001. PMID 26300312.
- Binhi, Vladimir N (2002). Magnetobiology: underlying physical problems. Repiev, A & Edelev, M (translators from Russian). San Diego: Academic Press. pp. 1–16. ISBN 978-0-12-100071-4. OCLC 49700531.
- Fry, Luther L.; Garg, Ashok; Guitérrez-Camona, Francisco; Pandey, Suresh K.; Tabin, Geoffrey, eds. (2004). Clinical Practice in Small Incision Cataract Surgery. CRC Press. p. 79. ISBN 0203311825.
- Sliney DH (1994). "UV radiation ocular exposure dosimetry". Doc Ophthalmol. 88 (3–4): 243–54. doi:10.1007/bf01203678. PMID 7634993.
- "UV Exposure & Your Health". UV Awareness. Retrieved 10 March 2014.
- Extremely Low Frequency Fields Environmental Health Criteria Monograph No.238, chapter 5, page 121, WHO
- Fishman, Scott; Ballantyne, Jane; Rathmell, James P., eds. (2010). Bonica's Management of Pain. Lippincott Williams & Wilkins. p. 1589. ISBN 9780781768276.
- Knight, Kenneth L.; Draper, David O. (2008). Therapeutic Modalities: The Art and the Science. Lippincott Williams & Wilkins. p. 288. ISBN 9780781757447.
- Yu, Chao; Peng, Rui-Yun (2017). "Biological effects and mechanisms of shortwave radiation: a review". Military Medical Research. 4: 24. doi:10.1186/s40779-017-0133-6. PMC 5518414. PMID 28729909.
- Boice JD Jr; Tarone RE (2011). "Cell phones, cancer, and children". Journal of the National Cancer Institute. 103 (16): 1211–3. doi:10.1093/jnci/djr285. PMID 21795667.
- "IARC classifies radiofrequency electromagnetic fields as possibly carcinogenic to humans" (PDF). press release N° 208 (Press release). International Agency for Research on Cancer. 31 May 2011. Retrieved 2 June 2011.
- "Electromagnetic fields and public health: mobile phones - Fact sheet N°193". World Health Organization. October 2014. Retrieved 2 August 2016.
- Limits of Human Exposure to Radiofrequency Electromagnetic Fields in the Frequency Range from 3 kHz to 300 GHz, Canada Safety Code 6, page 63
- Frey AH (1962). "Human auditory system response to modulated electromagnetic energy". J Appl Physiol. 17 (4): 689–92. doi:10.1152/jappl.1918.104.22.1689. PMID 13895081.
- Bergman W (1965), The Effect of Microwaves on the Central Nervous System (trans. from German) (PDF), Ford Motor Company, pp. 1–77, archived from the original (PDF) on 29 March 2018, retrieved 19 December 2018
- Michaelson, Sol M. (1975). "Radio-Frequency and Microwave Energies, Magnetic and Electric Fields" (Volume II Book 2 of Foundations of Space Biology and Medicine). In Calvin, Melvin; Gazenko, Oleg G (eds.). Ecological and Physiological Bases of Space Biology and Medicine. Washington, D.C.: NASA Scientific and Technical Information Office. pp. 409–52.
- Krans, Brian (1 September 2019). "Smartphone Radiation: iPhones Emitting Double Reported Levels". Ecowatch. Retrieved 9 September 2019.
- Characterization of 60GHz Millimeter-Wave Focusing Beam for Living-Body Exposure Experiments, Tokyo Institute of Technology, Masaki KOUZAI et al., 2009
- Sullivan, John Burke; Krieger, Gary R., eds. (2001). Clinical Environmental Health and Toxic Exposures. Lippincott Williams & Wilkins. p. 275. ISBN 9780683080278.
- "Laser Standards and Classifications". Rockwell Laser Industries. Retrieved 10 February 2019.
- "An Overview of the LED and Laser Classification System in EN 60825-1 and IEC 60825-1". Lasermet. Retrieved 10 February 2019.
- "What is the minimum safe distance from the welding arc above which there is no risk of eye damage?". The Welding Institute (TWI Global). Archived from the original on 10 March 2014. Retrieved 10 March 2014.
- James, William D.; et al. (2011). SPEC - Andrews' Diseases of the Skin (11 ed.). Elsevier Health Sciences. pp. 23–24. ISBN 9781437736199.
- Rafnsson, V; Olafsdottir E; Hrafnkelsson J; Sasaki H; Arnarsson A; Jonasson F (2005). "Cosmic radiation increases the risk of nuclear cataract in airline pilots: a population-based case-control study". Arch Ophthalmol. 123 (8): 1102–5. doi:10.1001/archopht.123.8.1102. PMID 16087845.
- Dobson, R. (2005). "Ozone depletion will bring big rise in number of cataracts". BMJ. 331 (7528): 1292–1295. doi:10.1136/bmj.331.7528.1292-d. PMC 1298891.
- Komarnitsky. "Case study of ultraviolet vision after IOL removal for Cataract Surgery".
- Griswold, M. S.; Stark, W. S. (September 1992). "Scotopic spectral sensitivity of phakic and aphakic observers extending into the near ultraviolet". Vision Research. 32 (9): 1739–1743. doi:10.1016/0042-6989(92)90166-G. ISSN 0042-6989. PMID 1455745.
- "Ultraviolet keratitis". Medscape. Retrieved 31 May 2017.
- Mironava, T.; Hadjiargyrou, M.; Simon, M.; Rafailovich, M. H. (20 July 2012). "The effects of UV emission from compact fluorescent light exposure on human dermal fibroblasts and keratinocytes in vitro". Photochemistry and Photobiology. 88 (6): 1497–1506. doi:10.1111/j.1751-1097.2012.01192.x. PMID 22724459.
- Nicole, Wendee (October 2012). "Ultraviolet leaks from CFLs". Environ. Health Perspect. 120 (10): a387. doi:10.1289/ehp.120-a387. PMC 3491932. PMID 23026199.
- U.S. Congress, Office of Technology Assessment (May 1989). Biological Effects of Power Frequency Electric & Magnetic Fields—Background Paper, OTA-BP-E-53 (PDF). Washington, DC: U.S. Government Printing Office. (over 100 pages)
- Li, De-Kun; Chen, Hong; Ferber, Jeannette R.; Odouli, Roxana; Quesenberry, Charles (2017). "Exposure to Magnetic Field Non-Ionizing Radiation and the Risk of Miscarriage: A Prospective Cohort Study". Scientific Reports. 7 (1): 17541. Bibcode:2017NatSR...717541L. doi:10.1038/s41598-017-16623-8. ISSN 2045-2322. PMC 5727515. PMID 29235463.
- Information page on electromagnetic fields at the World Health Organization web site
- CDC - Electric and Magnetic Fields - NIOSH Workplace Safety and Health Topic