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Disinfect Discriminately
August, 2010
Thorough Cleaning is Often Enough
By Paul Goldin
The terms disinfection and sanitization are often used interchangeably, but they perform different functions. Disinfectants have a higher kill capability for pathogenic bacteria compared to sanitizers. Very few disinfectants or sanitizers can sterilize or completely eliminate all micro-organisms.
Disinfection reduces potential infection hazards by reducing the number of micro-organisms present. This doesn’t necessarily eliminate all micro-organisms, but can reduce them to a level where they can no longer initiate infection. In contrast, a sanitizer must be capable of killing 99.999% (known as a 5 log reduction) of a specific bacterial test population within 30 seconds, but it may not necessarily destroy pathogenic or disease-causing bacteria.
Disinfectants should be used very carefully because they are also potentially harmful to humans and animals. As a general rule, they should never be mixed with other cleaning products because chemical reactions can occur. Some disinfectants will kill nearly all micro-organisms, while others kill a smaller range of disease-causing organisms but might be preferred because they are non-corrosive, non-toxic or inexpensive.
Commonly used disinfectants include:
- Quaternary ammonium compounds (or Quats), such as benzalkonium chloride, are a large group of related compounds. They are odourless, non-staining, non-corrosive to
- metals and relatively non-toxic at use-dilution concentrations. As sanitizers, they exhibit wide latitude in germicidal activity when used in hard water and are effective over a wide pH range.
- Hydrogen peroxide is often used in hospitals to disinfect surfaces and in the food packaging industry to disinfect foil containers. A 3% solution can also be used as an antiseptic. This disinfectant causes far fewer allergic reactions than alternative disinfectants. Nor does it produce residues or gases. Hydrogen peroxide is completely water soluble, thus safety depends on the applied concentration.
- Alcohol – usually ethanol or isopropanol – has wide microbiocidal effectiveness and is non-corrosive, but can constitute a fire hazard. These disinfectants evaporate quickly and have a limited activity in the presence of organic material. They are not effective against fungal or bacterial spores. Alcohols are more effective when combined with purified water – i.e.70% isopropyl alcohol or 62% ethyl alcohol is more effective than 95% alcohol.
- Bleach is a chemical that can remove or lighten color, usually via oxidation.
- Phenolics are effective at sanitization and disinfection in the presence of biological fluids and are tolerant towards a certain level of organic presence. However, they are relatively expensive and react with certain types of plastic surfaces. They are also difficult to oxidize and therefore difficult and expensive to dispose of in an environmentally suitable manner.
TARGETED APPLICATION RECOMMENDED
Facilities/maintenance managers can either select a disinfectant that works on the specific germs they are trying to eradicate, or a broad-spectrum product that works on all of the germs they might encounter. Application instructions are critical.
Cleaning staff must know when cleaning alone is enough and/or when disinfectant is required. The use of disinfectants should be limited to high-risk touch point areas where germs and infections are easily spread. For other areas, a thorough cleaning – preferably using green cleaning products – should suffice.
As an alternative to harsh chemicals, hydrogen peroxide may serve as an effective natural disinfectant. A combination of 3% hydrogen peroxide (the same strength in products sold over-the-counter in pharmacies) and undiluted white or apple cider vinegar is a proven and safe way to get rid of the Salmonella and E. coli bacteria. The two substances should be put into separate spray bottles and sprayed immediately after each other.
When more toxic chemicals are used, take care to review each product's material safety data sheet (MSDS) for other ingredients that may harm the user. For example, be wary of combined cleaner-disinfectants that contain butoxyethanol or ethanolamine.
Leaving the product on a surface for longer than recommended does not increase its effectiveness, but can lead to dangerous and unnecessary chemical exposures. Leaving it on for less time than recommended can inhibit its effectiveness. When using disinfecting wipes, avoid the spread of germs by ensuring that different wipes are used when cloths are passed from one surface to another.
Many chemicals contained in cleaners and disinfectants contribute to poor indoor air quality and have been implicated in the increase of respiratory ailments such as asthma. Exposure to and contact with cleaning chemicals can also cause eye, nose and throat irritation, skin rashes, headaches, dizziness, nausea and sensitization.
In commercial settings, cleaning chemicals are often purchased in concentrated solutions that require mixing and/or dilution by the employee who is responsible for application. Incorrect dilution of these products can cause adverse health effects for janitorial staff.
Certain cleaning chemicals may produce synergistic effects when mixed together, or repercussions more serious than those caused the each chemical by itself. For example, a quaternary ammonium compound used in combination with bleach will release gases called chloramines into the air. (See associated story, page ?)
Disinfectants such as quaternary ammonium compounds, phenols and bleach, which are used for routine cleaning in hospitals, the food service industry and by property managers, are registered pesticides. Health effects from long-term exposure to quaternary ammonium compounds include asthma and hypersensitivity syndrome.
Paul Goldin is Chief Sustainability Officer and Director of Marketing and Technical Services with Avmor.
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