PIVUC V1.0
Research type
Research Study
Full title
A two-Stage preliminary investigation of the visual and histological changes to healthy volunteer skin from single and repetitive exposure to virucidal Krypton-Chloride (KrCl) Far-UVC-emitting excimer lamps
IRAS ID
301627
Contact name
Sally H Ibbotson
Contact email
Sponsor organisation
University of Dundee
Clinicaltrials.gov Identifier
researchregistry7125, researchregistry.com
Duration of Study in the UK
1 years, 0 months, 1 days
Research summary
Far-UVC light can kill viruses and bacteria in the air. It can be used to sterilise indoor spaces, e.g. offices, shops and cafes, reducing the spread of infections such as the one that causes COVID-19 disease. We want to study the effect of Far-UVC light on peoples' skin. We will invite a total of 20 healthy volunteers, who have skin that tends to be sensitive to the sun, to take part. In Stage 1 of the study We will expose patches of the skin on their lower back/upper buttock of 8 participants to different amounts of Far-UVC and look for changes in the skin. We will measure changes by noting how the skin looks after the exposure, taking a type of photograph of the skin and also taking biopsies of the skin. A total of 4 skin biopsies will then be taken under a local anaesthetic. In Stage 2 we will also investigate the effect of exposing 12 participants’ lower back / upper buttock skin to Far-UVC over a number of days to see whether repeated doses cause any change to skin. Again, the look of the skin, specialised photographs and 3 skin biopsies will be used to measure any changes in the skin. The results of this study will help us understand whether Far-UVC has any effect on skin and whether it can be used safely to sterilise indoor air.
Lay Summary of results:
We wish to thank the individuals who participated in this research, without their voluntary involvement this study would not have been possible.
PIVUC: A two-stage preliminary investigation of the visual and histological changes to healthy volunteer skin from single and repetitive exposure to virucidal Krypton-Chloride (KrCl) Far-UVC-emitting excimer lamps The study was performed by Professor Sally H. Ibbotson and team at the Photobiology Unit, Ninewells Hospital, Dundee. The study was sponsored by the University of Dundee and funded by the Department of Health and Social Care, UK. There are no competing interests to declare.
The study was discussed with, and Participant Information Sheets (PIS) reviewed by, the Tayside Public and Patient Involvement (PPI) Group. The comments from this group were invaluable in informing the content of the protocol and PIS.
The study took place from the 19th of January 2022 to the 22nd of December 2022. Far-UVC light kills bacteria and viruses, including the coronavirus that causes COVID-19 disease. Special bulbs that give off Far-UVC light can be used to disinfect the air in public places, such as shops, cafes, bars and offices. This may be a way to reduce transmission of COVID-19 and other infections in the future. To make sure that Far-UVC light is safe, we needed to undertake this study to investigate its effect on people’s skin.
The main questions studied were:
• (Stage 1) What is the effect of different quantities of Far-UVC light on the skin?
• (Stage 2) What is the effect on the skin of repeated exposure to Far-UVC light?
In total 20 volunteers participated in the study, 8 in Stage 1 and 12 in Stage 2. The average age of volunteer in Stage 1 was 38 years (range 21 – 48 years) and in Stage 2 was 31.5 years (range 18 – 46 years).
In Stage 1 volunteers had small areas of skin on their upper buttock exposed to varying quantities of Far-UVC from a Krypton Chloride lamp and small areas on the lower back exposed to ultraviolet-B from a fluorescent lamp. The skin on the lower back / upper buttock was then assessed every hour for 8 hours and assessed again the following day. A few days later, skin on the upper buttock was then exposed to quantities of UVB and Far-UVC that were twice the highest quantity used previously that caused any visible change. Four small biopsies were then taken under local anaesthetic.
In Stage 2, volunteers had a small area of skin on the upper buttock exposed to Far-UVC. Around 5 hours later the same area was exposed to Far-UVC. This was repeated for the following 3 days. After the final Far-UVC exposure, a small area of the upper buttock was also exposed to ultraviolet-B. Skin biopsies were then taken from 3 sites: the Far-UVC exposed site, the ultraviolet-B site and unirradiated skin.
There were no adverse reactions during either stage of the study.
Stage 1:
No visual evidence of any change in skin appearance at any time point at any of the exposure doses. There was a small change in skin reflectance as measured using a reflectance spectrophotometer. The reflectance change appeared to peak around 4 hours and observations from 4 – 8 hours were statistically significantly different from baseline. 11 of the 16 biopsy samples from Far-UVC exposed sites were negative for DNA damage in the form of Cyclobutane Pyrimidine Dimers (CPD). Five biopsy samples were positive for CPD, of which four displayed only a few positive cells near the surface of the epidermis and one weakly expressed CPD in the superficial epidermis.
Stage 2:
There was no visual skin changes prior to or immediately following exposure to Far-UVC. There was a change in skin reflectance as measured using a reflectance spectrophotometer. The increase was cumulative with increasing exposure. The reflectance changes measured exceed the changes from Stage 1 but were not visible to the human eye. All biopsy samples from the Far-UVC site were negative for DNA damage in the form of CPD.
The results from this study, along with information from other studies, tells us that Far-UVC does not cause visible changes to the skin, even at very high quantities. This is because Far-UVC has very limited penetration into the top layer of skin; known as the epidermis and causes only minimal amounts of direct DNA damage in the very top layers of the epidermis. This is much less DNA damage than would be typically expected from normal daily sun exposure or that occurred after UVB exposure.
However, unlike sun exposure, Far-UVC is highly absorbed in the very top layer of “dead” skin cells called the Stratum Corneum (SC). Our hypothesis from the reflectance measurements is that the absorption of Far-UVC causes chemical changes within the SC. It is unlikely that these reflectance changes would have been observed at lower exposure doses, such as the current exposure limits. This does not mean that chemical changes would not have taken place, just that our ability to observe this with reflectance would not have been possible. What the chemical changes are, and whether they are significant from a health perspective, is unknown and requires further investigation.REC name
London - Bloomsbury Research Ethics Committee
REC reference
21/PR/1359
Date of REC Opinion
1 Dec 2021
REC opinion
Further Information Favourable Opinion