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Cadet J, Angelov D, Di Mascio P, Wagner JR. Contribution of oxidation reactions to photo-induced damage to cellular DNA. Photochem Photobiol 2024; 100:1157-1185. [PMID: 38970297 DOI: 10.1111/php.13990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2024] [Revised: 06/14/2024] [Accepted: 06/15/2024] [Indexed: 07/08/2024]
Abstract
This review article is aimed at providing updated information on the contribution of immediate and delayed oxidative reactions to the photo-induced damage to cellular DNA/skin under exposure to UVB/UVA radiations and visible light. Low-intensity UVC and UVB radiations that operate predominantly through direct excitation of the nucleobases are very poor oxidizing agents giving rise to very low amounts of 8-oxo-7,8-dihydroguanine and DNA strand breaks with respect to the overwhelming bipyrimidine dimeric photoproducts. The importance of these two classes of oxidatively generated damage to DNA significantly increases together with a smaller contribution of oxidized pyrimidine bases upon UVA irradiation. This is rationalized in terms of sensitized photooxidation reactions predominantly mediated by singlet oxygen together with a small contribution of hydroxyl radical that appear to also be implicated in the photodynamic effects of the blue light component of visible light. Chemiexcitation-mediated formation of "dark" cyclobutane pyrimidine dimers in UVA-irradiated melanocytes is a recent major discovery that implicates in the initial stage, a delayed generation of reactive oxygen and nitrogen species giving rise to triplet excited carbonyl intermediate and possibly singlet oxygen. High-intensity UVC nanosecond laser radiation constitutes a suitable source of light to generate pyrimidine and purine radical cations in cellular DNA via efficient biphotonic ionization.
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Affiliation(s)
- Jean Cadet
- Département de Médecine nucléaire et Radiobiologie, Faculté de Médecine, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Dimitar Angelov
- Laboratoire de Biologie et de Modélisation de la Cellule LMBC, Ecole Normale Supérieure de Lyon, CNRS, Université de Lyon, Lyon, France
- Izmir Biomedicine and Genome Center IBG, Dokuz Eylul University, Balçova, Izmir, Turkey
| | - Paolo Di Mascio
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, Brazil
| | - J Richard Wagner
- Département de Médecine nucléaire et Radiobiologie, Faculté de Médecine, Université de Sherbrooke, Sherbrooke, Quebec, Canada
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2
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Görlitz M, Justen L, Rochette PJ, Buonanno M, Welch D, Kleiman NJ, Eadie E, Kaidzu S, Bradshaw WJ, Javorsky E, Cridland N, Galor A, Guttmann M, Meinke MC, Schleusener J, Jensen P, Söderberg P, Yamano N, Nishigori C, O'Mahoney P, Manstein D, Croft R, Cole C, de Gruijl FR, Forbes PD, Trokel S, Marshall J, Brenner DJ, Sliney D, Esvelt K. Assessing the safety of new germicidal far-UVC technologies. Photochem Photobiol 2024; 100:501-520. [PMID: 37929787 DOI: 10.1111/php.13866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 09/28/2023] [Accepted: 09/29/2023] [Indexed: 11/07/2023]
Abstract
The COVID-19 pandemic underscored the crucial importance of enhanced indoor air quality control measures to mitigate the spread of respiratory pathogens. Far-UVC is a type of germicidal ultraviolet technology, with wavelengths between 200 and 235 nm, that has emerged as a highly promising approach for indoor air disinfection. Due to its enhanced safety compared to conventional 254 nm upper-room germicidal systems, far-UVC allows for whole-room direct exposure of occupied spaces, potentially offering greater efficacy, since the total room air is constantly treated. While current evidence supports using far-UVC systems within existing guidelines, understanding the upper safety limit is critical to maximizing its effectiveness, particularly for the acute phase of a pandemic or epidemic when greater protection may be needed. This review article summarizes the substantial present knowledge on far-UVC safety regarding skin and eye exposure and highlights research priorities to discern the maximum exposure levels that avoid adverse effects. We advocate for comprehensive safety studies that explore potential mechanisms of harm, generate action spectra for crucial biological effects and conduct high-dose, long-term exposure trials. Such rigorous scientific investigation will be key to determining safe and effective levels for far-UVC deployment in indoor environments, contributing significantly to future pandemic preparedness and response.
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Affiliation(s)
- Maximilian Görlitz
- Massachusetts Institute of Technology, Media Lab, Cambridge, Massachusetts, USA
- SecureBio, Inc., Cambridge, Massachusetts, USA
| | - Lennart Justen
- Massachusetts Institute of Technology, Media Lab, Cambridge, Massachusetts, USA
- SecureBio, Inc., Cambridge, Massachusetts, USA
| | - Patrick J Rochette
- Centre de recherche du CHU de Québec-Université Laval, Axe Médecine Régénératrice Quebec, Quebec City, Quebec, Canada
| | - Manuela Buonanno
- Center for Radiological Research, Columbia University Medical Center, New York City, New York, USA
| | - David Welch
- Center for Radiological Research, Columbia University Medical Center, New York City, New York, USA
| | - Norman J Kleiman
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York City, New York, USA
| | - Ewan Eadie
- Photobiology Unit, Ninewells Hospital, Dundee, UK
| | - Sachiko Kaidzu
- Department of Ophthalmology, Shimane University Faculty of Medicine, Izumo, Japan
| | - William J Bradshaw
- Massachusetts Institute of Technology, Media Lab, Cambridge, Massachusetts, USA
- SecureBio, Inc., Cambridge, Massachusetts, USA
| | - Emilia Javorsky
- Wyss Institute for Biologically Inspired Engineering at Harvard University, Boston, Massachusetts, USA
- Future of Life Institute, Cambridge, Massachusetts, USA
| | - Nigel Cridland
- Radiation, Chemicals and Environment Directorate, UK Health Security Agency, Didcot, UK
| | - Anat Galor
- Miami Veterans Affairs Medical Center, University of Miami Health System Bascom Palmer Eye Institute, Miami, Florida, USA
| | | | - Martina C Meinke
- Department of Dermatology, Venerology and Allergology, Center of Experimental and Applied Cutaneous Physiology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Johannes Schleusener
- Department of Dermatology, Venerology and Allergology, Center of Experimental and Applied Cutaneous Physiology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Paul Jensen
- Final Approach Inc., Port Orange, Florida, USA
| | - Per Söderberg
- Ophthalmology, Department of Surgical Sciences, Uppsala Universitet, Uppsala, Sweden
| | - Nozomi Yamano
- Division of Dermatology, Department of Internal Related, Kobe University, Kobe, Japan
| | - Chikako Nishigori
- Division of Dermatology, Department of Internal Related, Kobe University, Kobe, Japan
- Japanese Red Cross Hyogo Blood Center, Kobe, Japan
| | - Paul O'Mahoney
- Optical Radiation Effects, UK Health Security Agency, Chilton, UK
| | - Dieter Manstein
- Department of Dermatology, Cutaneous Biology Research Center, Harvard Medical School, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Rodney Croft
- International Commission on Non-Ionizing Radiation Protection (ICNIRP), Chair, Wollongong, New South Wales, Australia
- University of Wollongong, Wollongong, New South Wales, Australia
| | - Curtis Cole
- Sun & Skin Consulting LLC, New Holland, Pennsylvania, USA
| | - Frank R de Gruijl
- Department of Dermatology, Universiteit Leiden, Leiden, South Holland, The Netherlands
| | | | - Stephen Trokel
- Department of Ophthalmology, Columbia University Vagelos College of Physicians and Surgeons, New York City, New York, USA
| | - John Marshall
- Institute of Ophthalmology, University College London, London, UK
| | - David J Brenner
- Center for Radiological Research, Columbia University Medical Center, New York City, New York, USA
| | - David Sliney
- IES Photobiology Committee, Chair, Fallston, Maryland, USA
- Consulting Medical Physicist, Fallston, Maryland, USA
| | - Kevin Esvelt
- Massachusetts Institute of Technology, Media Lab, Cambridge, Massachusetts, USA
- SecureBio, Inc., Cambridge, Massachusetts, USA
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3
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Zhao J, Shang C, Yin R. A High-Radical-Yield Advanced Oxidation Process Coupling Far-UVC Radiation with Chlorinated Cyanurates for Micropollutant Degradation in Water. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:18867-18876. [PMID: 37158565 DOI: 10.1021/acs.est.3c00255] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Increasing the radical yield and reducing energy consumption would enhance the sustainability and competitiveness of advanced oxidation processes (AOPs) for micropollutant degradation in water. We herein report a novel AOP coupling far-UVC radiation at 222 nm with chlorinated cyanurates (termed the UV222/Cl-cyanurates AOP) for radical generation and micropollutant abatement in water. We experimentally determined the concentrations of HO•, Cl•, and ClO• in the UV222/Cl-cyanurates AOP in deionized water and swimming pool water. The radical concentrations are 10-27 times and 4-13 times, respectively, higher than those in the UV254/Cl-cyanurates AOP and the well-documented UV254/chlorine AOP under comparable conditions (e.g., same UV fluence and oxidant dosing). We determined the molar absorption coefficients and innate quantum yields of two chlorine species and two Cl-cyanurates at 222 nm and incorporated these parameters into a kinetic model. The model enables accurate prediction of oxidant photodecay rates as well as the pH impact on radical generation in the UV222/Cl-cyanurates AOP. We predicted the pseudo-first-order degradation rate constants of 25 micropollutants in the UV222/Cl-cyanurates AOP and demonstrated that many micropollutants can be degraded by >80% with a low UV fluence of 25 mJ cm-2. This work advances the fundamental photochemistry of chlorine and Cl-cyanurates at 222 nm and offers a highly effective engineering tool in combating micropollutants in water where Cl-cyanurates are suitable to use.
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Affiliation(s)
- Jing Zhao
- Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, P. R. China
| | - Chii Shang
- Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, P. R. China
- Hong Kong Branch of Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, P. R. China
| | - Ran Yin
- Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, P. R. China
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Young AR. The adverse consequences of not using sunscreens. Int J Cosmet Sci 2023; 45 Suppl 1:11-19. [PMID: 37799076 DOI: 10.1111/ics.12897] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Accepted: 03/10/2023] [Indexed: 10/07/2023]
Abstract
The adverse effects of solar ultraviolet radiation (UVR) on normal skin are well established, especially in those with poorly melanized skin. Clinically, these effects may be classified as acute, such as erythema or chronic such as keratinocyte and melanocyte skin cancers. Apart from skin type genetics, clinical responses to solar UVR are dependent on geophysical (e.g., solar intensity) and behavioural factors. The latter are especially important because they may result in 'solar overload' with unwanted clinical consequences and ever greater burdens to healthcare systems. Correctly used, sunscreens can mitigate the acute and chronic effects of solar UVR exposure. Laboratory studies also show that sunscreens can inhibit the initial molecular and cellular events that are responsible for clinical outcomes. Despite public health campaigns, global trends continue to show increasing incidence of all types of skin cancer. Large-scale epidemiological studies have shown the benefits of sunscreen use in preventing skin cancer, though it is likely that sunscreen use has not been optimal in such studies. It is evident that without substantial changes in sun-seeking behaviour, sunscreen use is a very important part of the defence against the acute and chronic effects of solar exposure. Ideally, sunscreens should be able to provide the level of protection that reduces the risk of skin cancer in susceptible skin types to that observed in heavily melanized skin.
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Affiliation(s)
- Antony R Young
- St John's Institute of Dermatology, King's College London, London, UK
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5
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Jmerik V, Kozlovsky V, Wang X. Electron-Beam-Pumped UVC Emitters Based on an (Al,Ga)N Material System. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:2080. [PMID: 37513091 PMCID: PMC10383474 DOI: 10.3390/nano13142080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 07/08/2023] [Accepted: 07/12/2023] [Indexed: 07/30/2023]
Abstract
Powerful emitters of ultraviolet C (UVC) light in the wavelength range of 230-280 nm are necessary for the development of effective and safe optical disinfection technologies, highly sensitive optical spectroscopy and non-line-of-sight optical communication. This review considers UVC emitters with electron-beam pumping of heterostructures with quantum wells in an (Al,Ga)N material system. The important advantages of these emitters are the absence of the critical problem of p-type doping and the possibility of achieving record (up to several tens of watts for peak values) output optical power values in the UVC range. The review consistently considers about a decade of world experience in the implementation of various UV emitters with various types of thermionic, field-emission, and plasma-cathode electron guns (sources) used to excite various designs of active (light-emitting) regions in heterostructures with quantum wells of AlxGa1-xN/AlyGa1-yN (x = 0-0.5, y = 0.6-1), fabricated either by metal-organic chemical vapor deposition or by plasma-activated molecular beam epitaxy. Special attention is paid to the production of heterostructures with multiple quantum wells/two-dimensional (2D) quantum disks of GaN/AlN with a monolayer's (1 ML~0.25 nm) thickness, which ensures a high internal quantum efficiency of radiative recombination in the UVC range, low elastic stresses in heterostructures, and high-output UVC-optical powers.
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Affiliation(s)
- Valentin Jmerik
- Ioffe Institute, 26 Politekhnicheskaya, 194021 St. Petersburg, Russia
| | - Vladimir Kozlovsky
- P. N. Lebedev Physical Institute, Leninsky Ave. 53, 119991 Moscow, Russia
| | - Xinqiang Wang
- State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nanooptoelectronics, School of Physics, Peking University, Beijing 100871, China
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Welch D, Kleiman NJ, Arden PC, Kuryla CL, Buonanno M, Ponnaiya B, Wu X, Brenner DJ. No Evidence of Induced Skin Cancer or Other Skin Abnormalities after Long-Term (66 week) Chronic Exposure to 222-nm Far-UVC Radiation. Photochem Photobiol 2023; 99:168-175. [PMID: 35614842 PMCID: PMC9691791 DOI: 10.1111/php.13656] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Accepted: 05/23/2022] [Indexed: 01/25/2023]
Abstract
Far-UVC radiation, typically defined as 200-235 nm, has similar or greater anti-microbial efficacy compared with conventional 254-nm germicidal radiation. In addition, biophysical considerations of the interaction of far-UVC with tissue, as well as multiple short-term safety studies in animal models and humans, suggest that far-UVC exposure may be safe for skin and eye tissue. Nevertheless, the potential for skin cancer after chronic long-term exposure to far-UVC has not been studied. Here, we assessed far-UVC induced carcinogenic skin changes and other pathological dermal abnormalities in 96 SKH-1 hairless mice of both sexes that were exposed to average daily dorsal skin doses of 400, 130 or 55 mJ cm-2 of 222 nm far-UVC radiation for 66 weeks, 5 days per week, 8 h per day, as well as similarly-treated unexposed controls. No evidence for increased skin cancer, abnormal skin growths or incidental skin pathology findings was observed in the far-UVC-exposed mice. In addition, there were no significant changes in morbidity or mortality. The findings from this study support the long-term safety of long-term chronic exposure to far-UVC radiation, and therefore its potential suitability as a practical anti-microbial approach to reduce airborne viral and bacterial loads in occupied indoor settings.
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Affiliation(s)
- David Welch
- Center for Radiological Research, Columbia University Irving Medical Center, New York, NY,Corresponding author: (David Welch)
| | - Norman J. Kleiman
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University Irving Medical Center, New York, NY
| | - Peter C. Arden
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University Irving Medical Center, New York, NY
| | - Christine L. Kuryla
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University Irving Medical Center, New York, NY
| | - Manuela Buonanno
- Center for Radiological Research, Columbia University Irving Medical Center, New York, NY
| | - Brian Ponnaiya
- Center for Radiological Research, Columbia University Irving Medical Center, New York, NY
| | - Xuefeng Wu
- Center for Radiological Research, Columbia University Irving Medical Center, New York, NY
| | - David J. Brenner
- Center for Radiological Research, Columbia University Irving Medical Center, New York, NY
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7
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Effect of ultraviolet C emitted from KrCl excimer lamp with or without bandpass filter to mouse epidermis. PLoS One 2022; 17:e0267957. [PMID: 35503791 PMCID: PMC9064105 DOI: 10.1371/journal.pone.0267957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 04/19/2022] [Indexed: 11/29/2022] Open
Abstract
It has been reported that 222-nm ultraviolet C (UVC) exerts a germicidal effect on bacteria and viruses as well as UV radiation emitted from a conventional germicidal lamp but is less toxic to the mammalian cells than that from a germicidal lamp. An excimer lamp filled with krypton chloride (KrCl) gas principally emits 222-nm UVC. However, the lamp also emits a wide band of wavelengths other than 222 nm, especially UVC at a longer wavelength than 222 nm and ultraviolet B, which cause DNA damage. There are some reports on the critical role of bandpass filters in reducing the harmful effect of UVC emitted from a KrCl excimer lamp in a human skin model and human subjects. However, the effectiveness of a bandpass filter has not been demonstrated in animal experiments. In the present study, mice were irradiated with UVC emitted from a KrCl excimer lamp with or without a bandpass filter. UVC emitted from an unfiltered KrCl lamp at doses of 50, 150 and 300 mJ/cm2 induced cyclobutyl pyrimidine dimer (CPD)-positive cells, whereas UVC emitted from a filtered lamp did not significantly increase CPD-positive cells in the epidermis. The present study suggested that the bandpass filter serves a critical role in reducing the harmful effect of emission outside of 222 nm to mouse keratinocytes.
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Welch D, Aquino de Muro M, Buonanno M, Brenner DJ. Wavelength-dependent DNA Photodamage in a 3-D Human Skin Model over the far-UVC and Germicidal-UVC Wavelength Ranges from 215 to 255 nm. Photochem Photobiol 2022; 98:1167-1171. [PMID: 35104367 PMCID: PMC9544172 DOI: 10.1111/php.13602] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Accepted: 01/28/2022] [Indexed: 11/27/2022]
Abstract
The effectiveness of UVC to reduce airborne‐mediated disease transmission is well established. However, conventional germicidal UVC (~254 nm) cannot be used directly in occupied spaces because of the potential for damage to the skin and eye. A recently studied alternative with the potential to be used directly in occupied spaces is far UVC (200–235 nm, typically 222 nm), as it cannot penetrate to the key living cells in the epidermis. Optimal far‐UVC use is hampered by limited knowledge of the precise wavelength dependence of UVC‐induced DNA damage, and thus we have used a monochromatic UVC exposure system to assess wavelength‐dependent DNA damage in a realistic 3‐D human skin model. We exposed a 3‐D human skin model to mono‐wavelength UVC exposures of 100 mJ/cm2, at UVC wavelengths from 215 to 255 nm (5 nm steps). At each wavelength, we measured yields of DNA‐damaged keratinocytes, and their distribution within the layers of the epidermis. No increase in DNA damage was observed in the epidermis at wavelengths from 215 to 235 nm, but at higher wavelengths (240–255 nm) significant levels of DNA damage was observed. These results support use of far‐UVC radiation to safely reduce the risk of airborne disease transmission in occupied locations.
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Affiliation(s)
- David Welch
- Center for Radiological Research, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | - Marilena Aquino de Muro
- Center for Radiological Research, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | - Manuela Buonanno
- Center for Radiological Research, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | - David J Brenner
- Center for Radiological Research, Columbia University Irving Medical Center, New York, NY, 10032, USA
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9
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Lawrence KP, Delinasios GJ, Premi S, Young AR, Cooke MS. Perspectives on Cyclobutane Pyrimidine Dimers-Rise of the Dark Dimers †. Photochem Photobiol 2021; 98:609-616. [PMID: 34706095 DOI: 10.1111/php.13551] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 10/14/2021] [Indexed: 02/06/2023]
Abstract
Some early reports demonstrate that levels of cyclobutane pyrimidine dimers (CPD) may increase after UVR exposure had ended, although these observations were treated as artifacts. More recently, it has been shown unequivocally that CPD formation does occur post-irradiation, with maximal levels occurring after about 2-3 h. These lesions have been termed "dark CPD" (dCPD). Subsequent studies have confirmed their presence in vitro, in mouse models and in human skin in vivo. Melanin carbonyls have a role in the formation of dCPD, but they have also been observed in amelanotic systems, indicating other, unknown process(es) exist. In both cases, the formation of dCPD can be prevented by the presence of certain antioxidants. We lack data on the spectral dependence of dCPD, but it is unlikely to be the same as for incident CPD (iCPD), which are formed only during irradiation. There is evidence that iCPD and dCPD may have different repair kinetics, although this remains to be elucidated. It is also unknown whether iCPD and dCPD have different biological properties. The formation of dCPD in human skin in vivo has implications for post solar exposure photoprotection, and skin carcinogenesis, with a need for this to be investigated further.
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Affiliation(s)
- Karl P Lawrence
- St. John's Institute of Dermatology, King's College London, London, UK
| | | | - Sanjay Premi
- Tumor Biology Department, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, USA
| | - Antony R Young
- St. John's Institute of Dermatology, King's College London, London, UK
| | - Marcus S Cooke
- Oxidative Stress Group, Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, Tampa, FL, USA
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10
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Sliney DH, Stuck BE. A Need to Revise Human Exposure Limits for Ultraviolet UV-C Radiation †. Photochem Photobiol 2021; 97:485-492. [PMID: 33590879 PMCID: PMC8252557 DOI: 10.1111/php.13402] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 01/28/2021] [Accepted: 02/09/2021] [Indexed: 01/03/2023]
Abstract
The COVID‐19 pandemic has greatly heightened interest in ultraviolet germicidal irradiation (UVGI) as an important intervention strategy to disinfect air in medical treatment facilities and public indoor spaces. However, a major drawback of UVGI is the challenge posed by assuring safe installation of potentially hazardous short‐wavelength (UV‐C) ultraviolet lamps. Questions have arisen regarding what appear to be unusually conservative exposure limit values in the UV‐C spectral band between 180 and 280 nm. We review the bases for the current limits and proposes some adjustments that would provide separate limits for the eye and the skin at wavelengths less than 300 nm and to increase both skin and eye limits in the UV‐C below 250 nm.
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Affiliation(s)
- David H Sliney
- Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, USA
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