Ethanol Alcohol vs Isopropyl Alcohol

Ethanol Alcohol vs Isopropyl Alcohol: Which is better?

The two most popular alcohols used as disinfectants are ethyl alcohol (or ethanol) and isopropyl alcohol . While both show potent germicidal activity, they have different applications in dental/medical environments. Let's review the similarities and differences between them and understand which one is better suited for your dental facility.

Physical Properties

Both ethanol and isopropyl alcohol are colorless and flammable liquids. Although their chemical composition varies slightly, they exhibit similar properties to each other. The vital difference between isopropyl alcohol and ethyl alcohol is that the latter is safe for human consumption, while the former is hazardous for ingestion. However, denaturants added to ethanol in industrial disinfecting and cleaning products make it unpalatable for consumption.

Mechanism of action

The viricidal activity of both these alcohols is similar. Both collapse the protein and lipid structure of bacterial and viral cell walls and membranes, eventually culminating in cell death. The Centre for Disease Control (CDC) suggests using between 60% and 90% of either ethyl alcohol or propanol for optimal efficacy.

Contact time

Contact time, also called "wet time", is the time required for a disinfectant to remain on a surface long enough to kill pathogens. A short contact time means that a disinfectant is potent and can quickly eliminate microbes, often within 30-60 seconds. Maxill's Tb Minuteman Nex Gen boasts a one minute kill time for SARS-CoV-2 and HIV-1. Hand sanitizers are great examples of short contact times and disinfect within 15 seconds. Conversely, a disinfectant with a long contact time means that the virus or bacteria will survive for a longer time. Water content in the disinfectant slows down evaporation; therefore, higher concentrations of alcohol also means that the solution evaporates rapidly, especially in high temperatures and humid conditions. Often, the alcohol solution evaporates before the contact time is reached, rendering the disinfectant ineffective.

Microbial activity

Both ethyl and isopropyl alcohol can kill common bacteria like salmonella, E. Coli, and Staphylococcus Aureus, as well as resistant bacteria like Mycobacterium tuberculosis and MRSA (antibiotic-resistant Staphylococcus Aureus). Alcohols are often the first choice for disinfecting tuberculosis bacteria. However, bacteria like E. Faecalis are growing more immune to alcohol-based disinfectants these days. Ethanol at its recommended concentrations (between 60% to 80%) is highly effective in wiping out all viruses encased in a lipid bilayer (enveloped viruses), such as herpes virus and influenza virus. It demonstrates potent viricidal activity against many non-enveloped viruses, such as rhinovirus, adenovirus, human immunodeficiency virus, and SARS-CoV-2 virus. However, it does not destroy the Hepatitis A virus or the poliovirus. 70% Isopropyl Alcohol is potent against lipid enveloped viruses but not fully active against non-enveloped viruses. Research shows that both ethanol and IPA are viricidal against the hepatitis B virus (HBV) and the herpes virus. In addition, according to the WHO, 70% ethyl alcohol is more efficient against the influenza virus than isopropyl alcohol.

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