Biology:Electromagnetic radiation and health

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Short description: Aspect of public health
Types of radiation in the electromagnetic spectrum
Types of radiation in the electromagnetic spectrum

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 atoms or break chemical bonds.[1] Extreme ultraviolet and higher frequencies, such as X-rays or gamma rays are ionizing, and these pose their own special hazards: see radiation poisoning.

The most common health hazard of radiation is sunburn, which causes between approximately 100,000 and 1 million new skin cancers annually in the United States.[2][3]

In 2011, the World Health Organization (WHO) and the International Agency for Research on Cancer (IARC) have classified radiofrequency electromagnetic fields as possibly carcinogenic to humans (Group 2B).[4]

Hazards

Dielectric heating from electromagnetic radiation can create a biological hazard. For example, touching or standing around an antenna while a high-power transmitter is in operation can cause burns (the mechanism is the same as that used in a microwave oven).[5]

The heating effect varies with the power and the frequency of the electromagnetic energy, as well as the inverse square of 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.[6]

Workplace exposure

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.[6] A measure of the heating effect is the specific absorption rate or SAR, which has units of watts per kilogram (W/kg). The IEEE[7] and many national governments have established safety limits for exposure to various frequencies of electromagnetic energy based on SAR, mainly based on ICNIRP Guidelines,[8] which guard against thermal damage.

Industrial installations for induction hardening and melting or on welding equipment may produce considerably higher field strengths and require further examination. If the exposure cannot be determined upon manufacturers' information, comparisons with similar systems or analytical calculations, measurements have to be accomplished. The results of the evaluation help to assess possible hazards to the safety and health of workers and to define protective measures. Since electromagnetic fields may influence passive or active implants of workers, it is essential to consider the exposure at their workplaces separately in the risk assessment.[9]

Low-level exposure

The World Health Organization (WHO) 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. In 2011, the WHO/International Agency for Research on Cancer (IARC)[10] has classified radiofrequency electromagnetic fields as possibly carcinogenic to humans (Group 2B), based on an increased risk for glioma, a malignant type of brain cancer, associated with wireless phone use.

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.[11] 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[12][13] and modulated RF and microwave fields.[14][15]

Effects by frequency

Warning sign next to a transmitter with high field strengths

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.[16][17][3][18]

Extremely low frequency

Extremely low frequency EM waves can span from 0 Hz to 3 kHz, though definitions vary across disciplines. The maximum recommended exposure for the general public is 5 kV/m.[19]

ELF waves around 50 Hz to 60 Hz are emitted by power generators, transmission lines and distribution lines, power cables, and electric appliances. Typical household exposure to ELF waves ranges in intensity from 5 V/m for a light bulb to 180 V/m for a stereo, measured at 30 centimetres (12 in) and using 240V power.[19] (120V power systems would be unable to reach this intensity unless an appliance has an internal voltage transformer.) Overhead power lines range from 1kV for local distribution to 1,150 kV for ultra high voltage lines. These can produce electric fields up to 10kV/m on the ground directly underneath, but 50 m to 100 m away these levels return to approximately ambient.[19] Metal equipment must be maintained at a safe distance from energized high-voltage lines.[20]

Exposure to ELF waves can induce an electric current. Because the human body is conductive, electric currents and resulting voltages differences typically accumulate on the skin but do not reach interior tissues.[21] People can start to perceive high-voltage charges as tingling when hair or clothing in contact with the skin stands up or vibrates.[21] In scientific tests, only about 10% of people could detect a field intensity in the range of 2-5 kV/m.[21] Such voltage differences can also create electric sparks, similar to a discharge of static electricity when nearly touching a grounded object. When receiving such a shock at 5 kV/m, it was reported as painful by only 7% of test participants and by 50% of participants at 10 kV/m.[21]

The International Agency for Research on Cancer (IARC) finds "inadequate evidence" for human carcinogenicity.[22]

Shortwave

Shortwave (1.6 to 30 MHz) diathermy (where EM waves are used to produce heat) 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.[23] 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.[24]

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, for example by overheating or inducing electrical currents.[25] 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 to 3.0 MHz. For uncontrolled exposure to the general public, the limit is 180/f2 between 1.34 and 30 MHz.[6]

Radio and microwave frequencies

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.[26]

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.[27] 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."[28][29]

Since 1962, the microwave auditory effect or tinnitus has been shown from radio frequency exposure at levels below significant heating.[30] 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.[31][32]

In 2019, reporters from the Chicago Tribune tested the level of radiation from smartphones and found that certain models emitted more than reported by the manufacturers and in some cases more than the U.S. Federal Communications Commission exposure limit. It is unclear if this resulted in any harm to consumers. Some problems apparently involved the phone's ability to detect proximity to a human body and lower the radio power. In response, the FCC began testing some phones itself rather than relying solely on manufacturer certifications.[33]

Microwave and other radio frequencies cause heating, and this can cause burns or eye damage if delivered in high intensity,[34] or hyperthermia as with any powerful heat source. Microwave ovens use this form of radiation, and have shielding to prevent it from leaking out and unintentionally heating nearby objects or people.

Millimeter waves

In 2009, the US TSA introduced full-body scanners as a primary screening modality in airport security, first as backscatter X-ray scanners, which use ionizing radiation and which the European Union banned in 2011 due to health and safety concerns. These were followed by non-ionizing millimeter wave scanners.[35] Likewise 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.[36][relevant? – discuss]

Infrared

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.[16]

Exposing skin to infrared radiation near visible light (IR-A) leads to increased production of free radicals.[37] Short-term exposure can be beneficial (activating protective responses), while prolonged exposure can lead to photoaging.[38]

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.[citation needed]

Visible light

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.[39]

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.[40][41] 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.[42]

Ultraviolet

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.[citation needed] 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.[43]

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.[17] 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.[44] 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.[45] Note that the lens filters UV light, so if it is removed via surgery, one may be able to see UV light.[46][47][undue weight? – discuss]

Prolonged exposure to ultraviolet radiation from the sun can lead to melanoma and other skin malignancies.[3] 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.[3] 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.[18]

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.[48]

ISO 7010 W005 Warning sign: Non-ionizing radiation

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.[49][50]

Regulation

In the United States, nonionizing radiation is regulated in the Radiation Control for Health and Safety Act of 1968 and the Occupational Safety and Health Act of 1970.[51]

See also


References

  1. ↑ Cleveland Jr, Robert F.; Ulcek, Jerry L. (August 1999). Questions and Answers about Biological Effects and Potential Hazards of Radiofrequency Electromagnetic Fields (4th ed.). Washington, D.C.: OET (Office of Engineering and Technology) Federal Communications Commission. https://transition.fcc.gov/Bureaus/Engineering_Technology/Documents/bulletins/oet56/oet56e4.pdf. Retrieved 2019-01-29. 
  2. ↑ "Cancer statistics, 2020". CA: A Cancer Journal for Clinicians 70 (1): 7–30. January 2020. doi:10.3322/caac.21590. PMID 31912902. 
  3. ↑ 3.0 3.1 3.2 3.3 "15. Ultraviolet Radiation Carcinogenesis". Holland-Frei Cancer Medicine (5th ed.). Hamilton, Ontario: B.C. Decker. 2000. ISBN 1-55009-113-1. https://www.ncbi.nlm.nih.gov/books/NBK20854/. Retrieved 31 January 2011. 
  4. ↑ Gaudin, Ph.D., Nicolas (31 May 2011). "IARC Classifies Radiofrequency Electromagnetic Fields As Possibly Carcinogenic to Humans". International Agency for Research on Cancer. https://www.iarc.who.int/wp-content/uploads/2018/07/pr208_E.pdf. 
  5. ↑ Barnes, Frank S.; Greenebaum, Ben, eds (2018). Biological and Medical Aspects of Electromagnetic Fields (3 ed.). CRC Press. p. 378. ISBN 978-1420009460. https://books.google.com/books?id=B-bKBQAAQBAJ&pg=PT378. Retrieved 29 January 2019. 
  6. ↑ 6.0 6.1 6.2 Cleveland Jr, Robert F.; Ulcek, Jerry L. (August 1999). "Questions and Answers about Biological Effects and Potential Hazards of Radiofrequency Electromagnetic Fields". OET Bulletin 56. Office of Engineering and Technology, Federal Communications Commission. p. 7. https://transition.fcc.gov/Bureaus/Engineering_Technology/Documents/bulletins/oet56/oet56e4.pdf. 
  7. ↑ "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. https://standards.ieee.org/findstds/standard/C95.1-2005.html. Retrieved 23 May 2015. 
  8. ↑ 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). International Commission on Non-Ionizing Radiation Protection". Health Physics 74 (4): 494–522. PMID 9525427. http://www.icnirp.de/documents/emfgdl.pdf. 
  9. ↑ Institute for Occupational Safety and Health of the German Social Accident Insurance. "Electromagnetic fields: key topics and projects". https://www.dguv.de/ifa/fachinfos/strahlung/elektromagnetische-felder/index-2.jsp. 
  10. ↑ [1]
  11. ↑ "What are electromagnetic fields? – Summary of health effects". https://www.who.int/peh-emf/about/WhatisEMF/en/index1.html. 
  12. ↑ "Embryological changes induced by weak, extremely low frequency electromagnetic fields". Journal of Anatomy 134 (Pt 3): 533–551. May 1982. PMID 7107514. 
  13. ↑ "Environmental magnetic fields inhibit the antiproliferative action of tamoxifen and melatonin in a human breast cancer cell line". Bioelectromagnetics 18 (8): 555–562. 1997. doi:10.1002/(SICI)1521-186X(1997)18:8<555::AID-BEM4>3.0.CO;2-1. PMID 9383244. https://zenodo.org/record/1235522. Retrieved 29 June 2019. 
  14. ↑ "Mobile phone affects cerebral blood flow in humans". Journal of Cerebral Blood Flow and Metabolism 26 (7): 885–890. July 2006. doi:10.1038/sj.jcbfm.9600279. PMID 16495939. 
  15. ↑ "Microwave frequency electromagnetic fields (EMFs) produce widespread neuropsychiatric effects including depression". Journal of Chemical Neuroanatomy 75 (Pt B): 43–51. September 2016. doi:10.1016/j.jchemneu.2015.08.001. PMID 26300312. 
  16. ↑ 16.0 16.1 Fry, Luther L.; Garg, Ashok; Guitérrez-Camona, Francisco et al., eds (2004). Clinical Practice in Small Incision Cataract Surgery. CRC Press. p. 79. ISBN 0203311825. https://books.google.com/books?id=Gswq6FvdU7oC&pg=PA79. Retrieved 31 January 2019. 
  17. ↑ 17.0 17.1 "UV radiation ocular exposure dosimetry". Documenta Ophthalmologica. Advances in Ophthalmology 88 (3–4): 243–254. 1994. doi:10.1007/bf01203678. PMID 7634993. 
  18. ↑ 18.0 18.1 "UV Exposure & Your Health". UV Awareness. http://www.uvawareness.com/uv-info/uv-exposure.php. 
  19. ↑ 19.0 19.1 19.2 World Health Organization (4 August 2016). "Radiation: Electromagnetic fields - Q&A". https://www.who.int/news-room/questions-and-answers/item/radiation-electromagnetic-fields. 
  20. ↑ Ubong Edet (Dec 6, 2017). "How to identify powerline voltage level and safe clearance level". https://www.hsewatch.com/powerline. 
  21. ↑ 21.0 21.1 21.2 21.3 Extremely Low Frequency Fields Environmental Health Criteria Monograph No.238, chapter 5, page 121, WHO
  22. ↑ "Power Lines, Electrical Devices, and Extremely Low Frequency Radiation". https://www.cancer.org/cancer/cancer-causes/radiation-exposure/extremely-low-frequency-radiation.html. 
  23. ↑ Fishman, Scott; Ballantyne, Jane; Rathmell, James P., eds (2010). Bonica's Management of Pain. Lippincott Williams & Wilkins. p. 1589. ISBN 978-0781768276. https://books.google.com/books?id=Pms0hxH8f-sC&pg=PA1589. Retrieved 1 February 2019. 
  24. ↑ Therapeutic Modalities: The Art and the Science. Lippincott Williams & Wilkins. 2008. p. 288. ISBN 978-0781757447. https://books.google.com/books?id=aMwKx91zI18C&pg=PA288. Retrieved 1 February 2019. 
  25. ↑ "Biological effects and mechanisms of shortwave radiation: a review". Military Medical Research 4: 24. 2017. doi:10.1186/s40779-017-0133-6. PMID 28729909. 
  26. ↑ "Cell phones, cancer, and children". Journal of the National Cancer Institute 103 (16): 1211–1213. August 2011. doi:10.1093/jnci/djr285. PMID 21795667. 
  27. ↑ "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. Archived (PDF) from the original on 1 June 2011. Retrieved 2 June 2011.
  28. ↑ "Electromagnetic fields and public health: mobile phones – Fact sheet N°193". World Health Organization. October 2014. https://www.who.int/mediacentre/factsheets/fs193/en/. 
  29. ↑ Limits of Human Exposure to Radiofrequency Electromagnetic Fields in the Frequency Range from 3 kHz to 300 GHz , Canada Safety Code 6, p. 63
  30. ↑ "Human auditory system response to modulated electromagnetic energy". Journal of Applied Physiology 17 (4): 689–692. July 1962. doi:10.1152/jappl.1962.17.4.689. PMID 13895081. 
  31. ↑ Bergman W (1965), The Effect of Microwaves on the Central Nervous System (trans. from German), Ford Motor Company, pp. 1–77, http://www.magdahavas.com/wordpress/wp-content/uploads/2010/12/German_Ford_Motor_company_The_Effect_of_Microwaves_on_The_Central_Nervous_System.pdf, retrieved 19 December 2018 
  32. ↑ Michaelson, Sol M. (1975). "Radio-Frequency and Microwave Energies, Magnetic and Electric Fields". in Calvin, Melvin; Gazenko, Oleg G. Ecological and Physiological Bases of Space Biology and Medicine. Washington, D.C.: NASA Scientific and Technical Information Office. pp. 409–452 [427–430]. https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19760019731.pdf. Retrieved 19 December 2018. 
  33. ↑ Sam Roe (August 21, 2019). "We tested popular cellphones for radiofrequency radiation. Now the FCC is investigating.". Chicago Tribune. https://www.chicagotribune.com/investigations/ct-cell-phone-radiation-testing-20190821-72qgu4nzlfda5kyuhteiieh4da-story.html. 
  34. ↑ "Microwaves, Radio Waves, and Other Types of Radiofrequency Radiation." American Cancer Society, http://www.cancer.org/cancer/cancer-causes/radiation-exposure/radiofrequency-radiation.html
  35. ↑ Khan, Farah Naz (2017-12-18). "Is That Airport Security Scanner Really Safe?" (in en). Scientific American. https://blogs.scientificamerican.com/observations/is-that-airport-security-scanner-really-safe/. 
  36. ↑ "Characterization of 60GHz Millimeter-Wave Focusing Beam for Living-Body Exposure Experiments, Tokyo Institute of Technology, Masaki KOUZAI et al., 2009". http://www.ieice.org/proceedings/EMC09/pdf/22S1-1.pdf. 
  37. ↑ "Cutaneous effects of infrared radiation: from clinical observations to molecular response mechanisms". Photodermatology, Photoimmunology & Photomedicine 19 (5): 228–234. October 2003. doi:10.1034/j.1600-0781.2003.00054.x. PMID 14535893. 
  38. ↑ "Biological effects and medical applications of infrared radiation". Journal of Photochemistry and Photobiology B: Biology 170: 197–207. May 2017. doi:10.1016/j.jphotobiol.2017.04.014. PMID 28441605. 
  39. ↑ Sullivan, John Burke; Krieger, Gary R., eds (2001). Clinical Environmental Health and Toxic Exposures. Lippincott Williams & Wilkins. p. 275. ISBN 978-0683080278. https://books.google.com/books?id=PyUSgdZUGr4C&pg=PA275. 
  40. ↑ "Laser Standards and Classifications". https://www.rli.com/resources/articles/classification.aspx. 
  41. ↑ "An Overview of the LED and Laser Classification System in EN 60825-1 and IEC 60825-1". https://www.lasermet.com/resources/classification_overview.php. 
  42. ↑ "What is the minimum safe distance from the welding arc above which there is no risk of eye damage?". The Welding Institute (TWI Global). http://www.twi-global.com/technical-knowledge/faqs/health-and-safety-faqs/faq-what-is-the-minimum-safe-distance-from-the-welding-arc-above-which-there-is-no-risk-of-eye-damage/. 
  43. ↑ James, William D.; Elston, Dirk; Berger, Timothy (2011). SPEC – Andrews' Diseases of the Skin (11 ed.). Elsevier Health Sciences. pp. 23–24. ISBN 978-1437736199. https://books.google.com/books?id=Ef_HllqkdqEC&pg=PA24. 
  44. ↑ "Cosmic radiation increases the risk of nuclear cataract in airline pilots: a population-based case-control study". Archives of Ophthalmology 123 (8): 1102–1105. August 2005. doi:10.1001/archopht.123.8.1102. PMID 16087845. 
  45. ↑ "Ozone depletion will bring big rise in number of cataracts". BMJ 331 (7528): 1292–1295. 2005. doi:10.1136/bmj.331.7528.1292-d. 
  46. ↑ Komarnitsky. "Case study of ultraviolet vision after IOL removal for Cataract Surgery". http://www.komar.org/faq/colorado-cataract-surgery-crystalens/ultra-violet-color-glow/. 
  47. ↑ "Scotopic spectral sensitivity of phakic and aphakic observers extending into the near ultraviolet". Vision Research 32 (9): 1739–1743. September 1992. doi:10.1016/0042-6989(92)90166-G. PMID 1455745. 
  48. ↑ "Ultraviolet keratitis". Medscape. http://emedicine.medscape.com/article/799025-overview. 
  49. ↑ "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. 20 July 2012. doi:10.1111/j.1751-1097.2012.01192.x. PMID 22724459. 
  50. ↑ "Ultraviolet Leaks from CFLs". Environmental Health Perspectives 120 (10): a387. October 2012. doi:10.1289/ehp.120-a387. PMID 23026199. 
  51. ↑ Michaelson, Solomon, ed (2012). Fundamental and Applied Aspects of Nonionizing Radiation. Springer Science & Business Media. p. xv. ISBN 978-1468407600. https://books.google.com/books?id=bezTBwAAQBAJ. Retrieved 30 January 2019. 

Further reading

External links



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