Science Behind Sanitizers: Effectiveness of Sanitizers: Quantity and Duration of Exposure

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Sanitizers

  • Hand sanitizers typically come in foam, gel, or liquid form

  • Hand sanitizers can be classified as one of two types: alcohol-based or alcohol-free.

  • Alcohol-based products typically contain between 60 and 95 percent alcohol, usually in the form of ethanol, isopropanol, or n-propanol.

  • At those concentrations, alcohol immediately denatures proteins, effectively neutralizing certain types of microorganisms.

  • Alcohol-free hand sanitizers contain something called quaternary ammonium compounds (usually benzalkonium chloride) instead of alcohol. These can reduce microbes but are less effective than alcohol. Also, antimicrobial agents, such as triclosan.

  • Many hand sanitizers also contain emollients (e.g., glycerin) that soothe the skin, thickening agents, and fragrance

  • Alcohol attacks and destroys the envelope protein that surrounds some viruses, including coronaviruses. This protein is vital for a virus’s survival and multiplication. But a hand sanitizer needs to be at least 60% alcohol in order to kill most viruses.

  • Hand sanitizers with less than 60 percent alcohol were also found to be less effective at killing bacteria and fungi and may only reduce the growth of germs rather than killing them outright.

  • Sneezing or coughing into your hands also requires more than just a pump of hand sanitizer to disinfect them. This is because if your hands are contaminated with mucous, the hand sanitizer might not work as well because mucous acts to protect microbes.

  • As a result, the best and most consistent way of preventing the spread of the coronavirus – and reducing your risk of contracting it – remains washing your hands with soap and water as a first choice and avoiding touching your face as much as possible.

  • Another strength of alcohol is that the bacteria it kills don’t develop a resistance to it, so alcohol doesn’t lose effectiveness with continued use.

Effectiveness of Sanitizers

  • Quantity

  • Duration of Exposure

  • Frequency of use

  • alcohol-based hand sanitizers, if rubbed thoroughly over finger and hand surfaces for a period of 30 seconds, followed by complete air-drying, can effectively reduce populations of bacteria, fungi, and some enveloped viruses (e.g., influenza A viruses)

  • Most hand sanitizers, however, are relatively ineffective against bacterial spores, nonenveloped viruses (e.g., norovirus), and encysted parasites (e.g., Giardia).

  • Research has indicated that certain antimicrobial compounds, such as triclosan, for example, may interfere with the function of the endocrine system. Environmental contamination from triclosan is another concern

  • Concerns -on product flammability and ingestion, both unintentional (e.g., by young children) and intentional (by individuals seeking to abuse alcohol)

  • Expiry: Alcohol is a shelf-stable chemical according to its safety data sheet from chemical-supplier Sigma Aldrich. This means that if alcohol is kept in a sealed container at room temperature it will remain at the same concentration for a very, very long time. However, alcohol evaporates easily because of its relatively low boiling point, and over time, as the bottle is opened and closed, some alcohol may escape and the concentration of alcohol in your hand sanitizer might start to decrease.

  • Benzethonium chloride is corrosive to the eyes and is irritating to the skin. Long-term effects from repeated exposure may cause dermatitis.

  • Triclosan harmful? - Triclosan has been found to be toxic and interferes with hormone systems.

  • Abnormal endocrine system/thyroid hormone signaling.

  • Weakening of immune system.

  • Children exposed to antibacterial products at an early age have an increased chance of developing allergies, asthma and eczema.

  • Uncontrolled cell growth.

  • Developmental and reproductive toxicity.

  • Triclosan is highly toxic to algae; researchers in Japan have observed that at least one species of green algae is especially susceptible to the effects of triclosan.

  • Quaternary ammonium compounds n Attached alkyl group affects activity n Works well with light soils and with detergent n Fairly effective anti-microbial n Fairly environmentally friendly n Not tolerant of mineralized water

  • Chlorine-containing not recommended except for out of control microbial situations n Very effective anti-microbial

  • Iodine-containing little used for wineries n Effective anti-microbial, except when diluted

  • Acid-anionic n Only effective at low pH n Can be corrosive n Not tolerant of mineralized water

  • Fatty acid sanitizers n Only effective at low pH n Can be corrosive n Can be used with acid rinse

  • Peroxides n Hydrogen peroxide, ozone (inorganic), peroxyacetic acid, peroxyborates (organic) n Very effective anti-microbials n Tolerant of mineralized water n Concentration dependent n Not corrosive n Can remove light biofilms in Environmentally friendly.

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