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Scientific bodies overseeing UV radiation protection recommend safety limits for exposure to ultraviolet radiation in the workplace based on published peer-reviewed data. To support this goal, a 3D model of the human cornea was used to assess the wavelength dependence of corneal damage induced by UV-C radiation. In the first set of experiments the models were exposed with or without simulated tears; at each wavelength (215–255 nm) cells with DNA dimers and their distribution within the epithelium were measured. Simulated tears reduced the fraction of damaged cells to an extent dependent on the wavelength and tissue layer. Subsequent experiments were performed with models exposed without simulated tears; yields of DNA-damaged cells and their distribution within the corneal epithelium were evaluated at each wavelength, together with other markers of cell and tissue integrity. Unlike relatively longer wavelengths, the range of wavelengths commonly referred to as far-UV-C (215–235 nm) only induced dimers in the uppermost layers of the epithelium and did not result in lasting damage or halt proliferation of the germinative cells. These results provide evidence for the recommended exposure limits for far-UV-C wavelengths, which have been proposed as a practical technology to reduce the risk of transmission of airborne diseases in occupied locations. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Steven Anthony Marino Sr., a respected scientist, passed away unexpectedly at the age of 77. Marino was born in Brooklyn, New York, and graduated from Rensselaer Polytechnic Institute in 1968. He worked at the Radiological Research Accelerator Facility (RARAF) at Brookhaven National Laboratory and later moved with RARAF to Columbia University. Marino played a crucial role in the development of RARAF into a neutron/charged-particle/microbeam facility. He was known for his dedication to providing accurate dosimetry and creating a biology-friendly environment for visiting radiobiologists. Marino's colleagues and friends remember him as a supportive and knowledgeable individual. He is survived by his wife, children, grandchildren, and siblings. [Extracted from the article]

Scientific bodies overseeing UV radiation protection recommend safety limits for exposure to ultraviolet light in the workplace based on published peer-reviewed data. To support this goal, a 3D model of the human cornea was used to assess the wavelength dependence of corneal damage induced by UVC light. In the first set of experiments the models were exposed with or without simulated tears; at each wavelength (215-255 nm) cells with DNA dimers and their distribution within the epithelium were measured. Simulated tears reduced the fraction of damaged cells to an extent dependent on the wavelength and tissue layer. Another set of models were exposed without tears; yields of DNA-damaged cells and their distribution within the corneal epithelium were evaluated at each wavelength, together with other markers of cell and tissue integrity. Unlike relatively longer wavelengths, the range commonly referred to as far-UVC (215-235 nm) only induced dimers in the uppermost layers of the epithelium and did not result in lasting damage or halt proliferation of the germinative cells. These results provide evidence for the recommended exposure limits for far-UVC wavelengths, which have been proposed as a practical technology to reduce the risk of transmission of airborne diseases in occupied locations., Competing Interests: The authors declare the following pending patent: Patent Title: “Apparatus, method and system for selectively affecting and/or killing a virus”. Applicant: The Trustees of Columbia University in the City of New York. Inventors: Gerhard Randers-Pehrson, David Jonathan Brenner, Alan Bigelow. Application #: US20180169279A1. Aspect of manuscript covered in patent application: Spectrum filtering elements such as multilayer dielectric filters or chemical filters are used to remove unwanted wavelengths, or those wavelengths that can be outside of the preferable range of wavelengths. URL: https://patents.google.com/patent/US20180169279A1/en?oq=20200085984. The other authors have no competing interests.