Lessons we learned about alcohol as a disinfectant here at EadsCo Cleaning.

A Brief History of Fighting Infection

Early Discoveries and Natural Immunity

430 BC: General Thucydides observed natural immunity in survivors of the plague in Athens, noting that those who recovered did not get sick again.
1000 AD: The Chinese practiced variolation, an early form of inoculation against smallpox, by using material from smallpox pustules.

The Birth of Vaccination

1798: Edward Jenner pioneered the first official vaccination by using cowpox to protect against smallpox, laying the foundation for modern immunology.

Germ Theory and Antiseptic Practices

1837: Theodore Schwann described the role of microorganisms in putrefaction and fermentation.
1847: Ignaz Semmelweis demonstrated that hand disinfection dramatically reduced death rates in maternity wards, though his findings were initially dismissed.
1854-1885: Louis Pasteur developed the germ theory of disease, pasteurization, and vaccines for rabies and chicken cholera.
1867: Joseph Lister introduced aseptic techniques in surgery using carbolic acid, significantly reducing postoperative infections.

Advances in Immunology and Antibiotics

1883: Elie Metchnikoff proposed that cells (phagocytes) are involved in the body’s defense against microorganisms.
1890: Emil von Behring and Shibasaburo Kitasato discovered antitoxins (antibodies), leading to the development of diphtheria and tetanus antitoxins.
1928: Alexander Fleming discovered penicillin, the first true antibiotic, revolutionizing the treatment of bacterial infections.

A Brief History of the Use of Alcohol as a Disinfectant

The use of alcohol as a disinfectant has a rich history, evolving over centuries as our understanding of microorganisms and infection control has improved. Here are some key milestones:

Early Uses of Alcohol as a Disinfectant

Ancient Times: Alcoholic beverages like wine and beer were used for their antiseptic properties, although their effectiveness was limited due to low alcohol content and high sugar levels.
Middle Ages: Alcohol was used in wound care, but its high concentration needed for effective disinfection also caused damage to tissues, inhibiting healing.

Scientific Discoveries

1676: Antonie van Leeuwenhoek discovered microorganisms using a microscope, which laid the groundwork for understanding the role of microbes in infection.
19th Century: The development of germ theory by Louis Pasteur and the introduction of antiseptic techniques by Joseph Lister highlighted the importance of disinfectants in medical practice.

Alcohol as a Disinfectant

Late 1800s: The use of alcohol as a disinfectant became more widespread. Joseph Lister’s work with carbolic acid (phenol) in surgical antisepsis paved the way for the use of other antiseptics, including alcohol.
20th Century: The combination of alcohol with other disinfectants, such as quaternary ammonium compounds, was found to enhance their effectiveness, leading to broader use in healthcare settings.

Modern Applications

Today: Isopropyl alcohol and ethanol are commonly used as disinfectants in healthcare, laboratories, and households. They are effective against a wide range of pathogens, including bacteria and viruses.

Differences Between 70% and 90% Isopropyl Alcohol

Isopropyl alcohol (IPA) is a widely used disinfectant and antiseptic. The primary difference between 70% and 90% IPA lies in their concentration of alcohol and water.

70% Isopropyl Alcohol: Contains 70% alcohol and 30% water. This concentration is often considered optimal for disinfecting purposes because the water content slows the evaporation rate, allowing the alcohol to remain in contact with the surface longer and penetrate cell walls more effectively.
90% Isopropyl Alcohol: Contains 90% alcohol and 10% water. This higher concentration evaporates quickly, which can limit its effectiveness in killing microorganisms as it may not stay on the surface long enough to penetrate cell walls.

Effectiveness in Fighting Disease and Infections

70% IPA is generally more effective for disinfecting surfaces and killing bacteria and viruses compared to 90% IPA. The presence of water in 70% IPA is crucial as it facilitates the denaturation of proteins, which is essential for killing microorganisms.

Bacteria: 70% IPA can penetrate the cell wall more effectively, leading to the coagulation of proteins and the death of the bacterial cell.
Viruses: Alcohol solutions with at least 60% alcohol are effective against enveloped viruses (e.g., influenza, HIV, SARS-CoV-2) by disrupting their lipid membranes. Non-enveloped viruses (e.g., norovirus) are more resistant to alcohol-based disinfectants.

Differences Between Bacteria and Viruses

Bacteria: Single-celled microorganisms that can live in various environments. They have a cell wall and can reproduce independently. Some bacteria are beneficial, while others can cause infections.
Viruses: Much smaller than bacteria, viruses consist of genetic material (DNA or RNA) enclosed in a protein coat. They require a host cell to replicate and can cause a range of diseases.

Interaction with Cell Walls

70% IPA is more effective at penetrating cell walls due to its water content, which helps to open up the cell membrane and allows the alcohol to enter and denature proteins.

90% IPA: The higher concentration can coagulate proteins on the cell surface too quickly, creating a protective barrier that prevents the alcohol from penetrating deeper into the cell.

Disinfecting Surfaces

70% IPA is recommended for disinfecting surfaces because it remains on the surface longer, ensuring thorough disinfection. It is effective against a wide range of pathogens and is commonly used in healthcare settings, households, and industries.

Use on Human Skin

70% IPA is also preferred for use on human skin as it is less harsh and less likely to cause irritation compared to higher concentrations. It is commonly used for disinfecting minor cuts and scrapes, as well as in hand sanitizers.

Conclusion

The journey of alcohol as a disinfectant from an ancient remedy to a modern disinfectant underscores the importance of scientific discovery and innovation in improving public health. Alcohol remains a vital tool in infection control, thanks to its proven efficacy and versatility.

In summary, 70% isopropyl alcohol as a disinfectant is generally more effective for disinfecting purposes due to its optimal balance of alcohol and water, which allows it to penetrate cell walls and denature proteins more effectively. It is suitable for both surface disinfection and use on human skin, making it a versatile and essential disinfectant.

Here at EadsCo Cleaning, we broadly and liberally use spray bottles containing 70% iso-propyl alcohol as a disinfectant. We provide them in the office and in our vehicles. When we are experiencing a peak cold or flu season, we have our staff spray their hand and surfaces regularly to defend against the spread of infection. Ironically, we have found that the 70% solution actually results in soft and health skin when compared to ‘fancy’ or brand named hand sanitizers.

Please see the references below for additional information on alcohol as a disinfectant or to investigate further.