Alcohols as a component of disinfectants

In the course of official monitoring of genetic engineering facilities, the decades-old practice of using home-made ethanol mixtures has been identified as worthy of criticism in some German states. But what is the basis, what foundations, and what justification for this criticism?

At least these requirements do not come from the Genetic Engineering Safety Ordinance (GenTSV), as it does not specify disinfectant categories. Annex 2 to Section 14, point 15, only mentions: “In the event of a release of genetically modified organisms (GMOs), effective disinfectants and specific disinfection procedures must be available.”

However, the disinfectant effectiveness of ethanol is undisputed. Ethanol penetrates bacteria particularly rapidly, even in the presence of lipid layers. Ethanol works, among other things, by denaturing proteins, inactivating enzymes (e.g., dehydrogenases in E. coli), and prolonging the latency phase of bacteria (e.g., in Enterobacter aerogenes). Ethanol also exerts a bacteriostatic effect by inhibiting the production of metabolites required for rapid cell division. Its spectrum of activity is characterized by good and rapid efficacy against gram-positive and gram-negative pathogens, as well as against mycobacteria and fungi. However, it has no effect against spores. It has some good virucidal activity; it is adequate against enveloped viruses but insufficient against non-enveloped viruses (see also Buschhausen-Denker/Deitenbeck, 1995). The requirements of the GenTSV for disinfectants are therefore met for most biological substances.

However, the reason for avoiding ethanol may be due to its flammability. Alcohol evaporates very quickly and has a low flash point. Furthermore, after prolonged use, alcohol causes rubber and some plastic parts to swell and harden. However, many commercially available surface disinfectants also contain significant amounts of ethanol and other short-chain alcohols, and many of these products are also flammable. A general rejection of homemade ethanol mixtures for disinfection is therefore not entirely understandable.

Conclusion: As with any other hazardous substance, the use of ethanol as a disinfectant must be preceded by a risk assessment (RAA) conducted and documented by qualified personnel. The relevant requirements for this RAA and the health considerations will be further discussed in a subsequent article.