No Evidence of Induced Skin Cancer or Other Skin Abnormalities after Long‐Term (66 week) Chronic Exposure to 222‐nm Far‐UVC Radiation

Abstract

Far-UVC radiation, typically defined as 200-235 nm, has similar or greater anti-microbial efficacy compared to 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 396 mJ/cm 2 , 126 mJ/cm 2 or 56 mJ/cm 2 of 222 nm far-UVC radiation for 66 weeks, 5 days per week, 8 hours 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..

Evaluation of Single-Pass Disinfection Performance of Far-UVC Light on Airborne Microorganisms in Duct Flows

“…The use of far-UVC irradiation is considered a promising solution for efficient and safe disinfection based on the limited results of recent studies. ,− , Although some studies ,, showed that far-UVC exposure is likely to be safe for human skin and eyes, more long-term evidence on the harmlessness of far-UVC exposure is needed. Currently, there are regulatory exposure limits for 222 nm far-UVC irradiation.…”

“…Currently, there are regulatory exposure limits for 222 nm far-UVC irradiation. For example, ACGIH (American Conference of Governmental and Industrial Hygienists) 8 h threshold limit values for 222 nm far-UVC are around 160 mJ/cm 2 for the eyes and 480 mJ/cm 2 for skin, which are much higher than the limit for 254 nm UV (6 mJ/cm 2 ). ,, However, the health issues related to exposure to 222 nm far-UVC are not concerns for in-duct or in-channel applications.…”

Disinfecting the air with far-ultraviolet light

“…On the safety side, Brenner and colleagues reported in May that they had exposed hairless mice to the radiation for 66 weeks without detecting any skin cancer 7 . Their upcoming research will focus on the risk to the eyes, and further investigate the mechanisms of how 222 nm radiation damages pathogens.…”

Far-UVC Radiation for Disinfecting Hands or Gloves?

“…However, almost 20 years ago, Sosnin et al [ 6 ] found that there is short-wavelength UVC radiation, which damages eukaryotic cells less than prokaryotic cells. Meanwhile, it has been found that human skin tolerates UV radiation in the so-called far-UVC range of about 200–230 nm relatively well [ 7 , 8 , 9 , 10 , 11 , 12 , 13 ]. This radiation is almost completely absorbed in the stratum corneum and does not reach deeper skin layers.…”