Benzalkonium chloride

Dear Editor,

To expand upon our previous letter regarding the epidemic of occupational related facial dermatoses in the Covid-19 pandemic (1), we now raise concerns relating to the introduction of reusable face mask respirators and associated recommended cleansing practices. The Sundström SafetyTM mask has been recently introduced within our trust. Staff are advised to clean this after each use with a ClinellTM Univeral wipe (GAMA Healthcare Ltd), then to leave to dry before wearing once more.

According to the material safety data sheet (2) ClinellTM Universal Wipes contain several disinfectants and antiseptics, namely benzalkonium chloride (CAS no. 68424-85-1), didecyl dimethyl ammonium chloride (CAS no. 7173-51-5) and polyhexamethylene biguanide (PHMB) (CAS no. 27083-27-8).

GAMA Healthcare report ClinellTM Universal Wipes "are effective against coronavirus in 60 seconds" according to EN14476 (3). Interestingly, Kampf et al. (4) in a review of the literature on the persistence of human and veterinary coronaviruses on inanimate surfaces and on inactivation strategies identify that "agents such as 0.05–0.2% benzalkonium chloride or 0.02% chlorhexidine digluconate are less effective" than disinfection with 62-71% ethanol, 0.5% hydrogen peroxide or 0.1% sodium hypochlorite when studied as single agents.

Our concern relates to irritant exposure to facial skin. We are already seeing increasing numbers of staff presenting to our Occupational Dermatology Clinic within one week of switching from disposable FFP3 masks to the reusable model and we are highly suspicious this is a consequence of current recommended cleansing practices. Benzalkonium chloride is a well-recognised irritant, especially with frequent use (5). Although staff are recommended to leave the wipe residue to dry before applying the face mask benzalkonium chloride is not a volatile agent and therefore would persist on surfaces after drying (6). With such prolonged wear as is currently necessary amongst intensive care staff it is unsurprising irritant contact dermatitis develops along the pressure lines of the mask.

In the absence of a widely available alternative to ClinellTM Universal Wipes, we recommend staff rinse masks with tap water after cleaning. Masks should be dried before applying. Staff should always wear gloves when handling the wipes for similar reasons.

References1. Ferguson FJ, Cunningham L, White IR, McFadden JP. Occupational facial dermatitis in the Covid-19 pandemic. https://www.bmj.com/content/369/bmj.m1743/rr-2 (last accessed 18th May 2020)2. Safety Data Sheet version 9, ClinellTM Universal Wipes. https://gama.getbynder.com/m/255ecfc30ab22332/original/Universal-Wipes-S... (last accessed 17th May 2020)3. https://gamahealthcare.com/latest/clinell-efficacy-against-wuhan-coronav... (last accessed 17th May 2020)4. Kampf G, Todt D, Pfaender S, Steinmannb E. Persistence of coronaviruses on inanimate surfaces and their inactivation with biocidal agents. J Hosp Infect. 2020 Mar; 104(3): 246–251.5. Hann S, Hughes TM, Stone NM. Flexural allergic contact dermatitis to benzalkonium chloride in antiseptic bath oil. Br J Dermatol. 2007 Oct; 157(4):795-8.6. Bondurant SW, Duley CM, Harbell JW. Demonstrating the persistent antibacterial efficacy of a hand sanitizer containing benzalkonium chloride on human skin at 1, 2, and 4 hours after application. J Infect Control. 2019 Aug; 47(8):928-932.

Competing interests: No competing interests