Reviewing the evidence of antimicrobial activity of glycols.

In the 1940 s and 1950 s, researchers seeking safe and novel ways to eliminate airborne pathogens from enclosed spaces, investigated glycol vapours as a method of disinfection. More recently, the COVID-19 pandemic highlighted the need for a non-toxic aerial disinfectant that can be used in the presence of people. This scoping review is intended to analyse the early and more recent literature on glycol disinfection, scrutinising the methodologies used, and to determine if the use of glycols as modern-day disinfectants is justified. PRISMA-ScR guidelines were used to assess the 749 articles retrieved from the Web of Science platform, with 46 articles retained after the search strategy was applied. Early studies generally demonstrated good disinfection capabilities against airborne bacteria and viruses, particularly with propylene glycol (PG) vapour. Vapour pressure, relative humidity, and glycol concentration were found to be important factors effecting the efficacy of glycol vapours. Contact times depended mainly on the glycol application method (i.e. aerosolization or liquid formulation), although information on how glycol efficacy is impacted by contact time is limited. Triethylene glycol (TEG) is deemed to have low toxicity, carcinogenicity and mutagenicity and is registered for use in air sanitisation and deodorisation by the US Environmental Protection Agency. Glycols are also used in liquid formulations for their antimicrobial activity against a wide range of microorganisms although when used as a non-active excipient in products, their contribution to antimicrobial efficacy is rarely assessed. The appropriate use of liquid glycol containing formulations were found to positively impact the antimicrobial capabilities of disinfectants when used at temperatures below zero, food preservatives and dental medicaments. Providing modern delivery technology can accurately control environmental conditions, the use of aerosolised glycol formulations should lead to successful disinfection, aiding infection prevention and control regimens.