SARS-CoV-2: Selecting and applying an appropriate surface disinfectant

Introduction

According to CDC, the novel coronavirus (SARS-CoV-2) is spread from person-to-person1.  This happens most frequently during close contact (within 6 feet) with an infected individual via respiratory droplets when an infected individual coughs or sneezes.

The transmission of SARS-CoV-2 to persons from surfaces contaminated with the virus is not clearly documented1.  There is, however, evidence that suggests SARS-CoV-2 may remain viable for hours to days on surfaces made from a variety of materials2.  Cleaning and disinfecting of surfaces is a best practice measure for prevention of transmission of SARS-CoV-2 and other viral respiratory illness.

Many laboratories already have stocks of disinfectants on hand.  Identifying which of these are effective against SARS-CoV-2 is a critical step in preparing personnel for the re-opening of WSU research facilities and ensuring a safe work environment.

Environmental Protection Agency (EPA) Registered Disinfectants3

EPA Selected Disinfectants will have an EPA Registration Number, which can be found on the label, typically proceeded by the phrase "EPA Registration No.", or "EPA Reg. No.". The number is specific to the company who submitted the disinfectant for registration and the sequence the product was submitted to the EPA4.

Ensure your product is an EPA-approved disinfectant that is effective against SARS-CoV-2.  The list of EPA-approved disinfectants can be found at the following link: https://www.epa.gov/pesticide-registration/list-n-disinfectants-use-against-sars-cov-2.  Use this list to search for the EPA Registration Number found on a label.

  • Examples of EPA-approved disinfectants commonly found in WSU laboratories are listed in Table 1.
  • The EPA number for each product can be found on the original container for registered products.
  • Pay close attention to the required contact time listed on the EPA website for SARS-CoV-2.  This may differ from the recommended duration listed on the container for viricidal activity.

Table 1.  Examples of commonly used surface disinfectants in WSU Research Laboratories and the EPA recommended contact time for SARS-CoV-2.

Product Name EPA Registration Number Active Ingredient EPA Recommended Contact Time (minutes)*
AccelTB** 74559-1 Hydrogen Peroxide 1
Peroxigard RTU** 74559-9 Hydrogen Peroxide 0.5
PREempt RTU 74559-1 Hydrogen Peroxide 1
Spartan Diffense 5741-28 Sodium hypochlorite 0.5
Cavicide Bleach 46781-15 Sodium hypochlorite 3
Clorox Healthcare Bleach Germicidal Cleaner Spray 56392-7 Sodium hypochlorite 1
Lysol Disinfectant Spray 777-99 Quaternary ammonium compounds plus ethanol 10
Cavicide 46781-6 Quaternary ammonium compounds plus isopropanol 2
TB-Cide QUAT 1839-83 Quaternary ammonium compounds 10
BNC-15*** 6836-348 Quaternary ammonium compounds 5
DisCide Ultra Towelettes 10492-4 Quaternary ammonium compounds plus isopropanol 0.5

*Confirm that information for your product is up to date using the EPA online tool: https://www.epa.gov/pesticide-registration/list-n-disinfectants-use-against-sars-cov-2

**These disinfectants are routinely used in the WSU DLAR facilities

***BNC-15 is the primary disinfectant used by WSU FP&M for environmental cleaning

Active Ingredients5,6

Hydrogen Peroxide: Stable and effective on surfaces.  Shelf stable when stored according to manufacturer's recommendations.  Effective concentration range is 3% to 25%, but 7.5% is typically used.

Application – Whole room and surface disinfectant. Wound disinfectant.

Equipment Types – Depending on how it is used, can be safe to use on/around electronic equipment. Some plastics and some metals can have a dramatic effect on the available hydrogen peroxide by absorbing, adsorbing or decomposing it at a higher rate.

Potential Hazards – Concentrated forms can cause severe skin burns and eye damage; harmful if inhaled. As an oxidizer, it can contribute to creation and spread of fire. Whole room disinfection creates a severe inhalation hazard that is controlled by following manufacturer's instructions.

Peracetic acid or Peroxyacetic acid: These are a similar class of disinfectants as hydrogen peroxide and can sometimes be found mixed with hydrogen peroxide. These disinfectants decompose to safe by-products (acetic acid and oxygen); remain active in the presence of organic loads; effective at low temperatures; and leaves no residue. Considered a more potent biocide than hydrogen peroxide, but is unstable, particularly when diluted, which affects efficacy and contact time.

Application – Its main application is as a low-temperature liquid sterilant for medical devices, but it is also used as an environmental surface sterilant.

Equipment Types – Chemically sterilize medical (e.g., endoscopes, arthroscopes), surgical, and dental instruments. Peracetic acid can corrode copper, brass, bronze, plain steel, and galvanized iron. Manufacturers may have reduced these effects through additives and pH modifications. May require water rinse.

Potential Hazards – Flammable, corrosive, and an irritant. Can cause skin burns and eye damage. Harmful if inhaled.

Chlorine and Chlorine Compounds: The most commonly known of these disinfectants is sodium hypochlorite (bleach). Other chlorine compounds include: Chlorine dioxide; Hydrochloric acid; Hydrogen chloride; Hypochlorous acid; Sodium chlorite; Sodium dichloroisocyanurate; Sodium dichloro-S-triazinetrione.

The effectiveness of these compounds is based on the amount of free hypochlorous acid found in solution, which also affects required contact time. All these compounds degrade over time and are inactivated in the presence of organic matter (e.g. blood, tissue, concentration of microbes). 10% bleach solution typically has 5150-6250 ppm free chlorine.

Application – Surface disinfectant; for submerging items; and for disinfecting liquid cultures.

Equipment Types – Floors, countertops, lab benches, surfaces of computers (apply to rag, not directly to computer). Will discolor and degrade fabrics. Not recommended for use on aluminum surfaces. Can be corrosive to stainless steel, soft metals such as brass, as well as to rubber and polyurethane. May require a rinse with 70% ethanol or water to reduce corrosion.

Potential Hazards – Ocular and inhalation irritation. May cause burns to skin. Release of toxic chlorine gas when mixed with ammonia or acid. When pre-cleaning surfaces, must ensure the cleaner is compatible with the chlorine disinfectant to prevent the creation of toxic by-products.

Sodium Hypochlorite:  Standard household bleach (sodium hypochlorite) is broad acting, but once diluted remains effective for limited time periods7. Longer contact times are required for surface disinfection with diluted household bleach (i.e. 30 minutes).  Commercially available sodium hypochlorite products have extended shelf life and have shorter, EPA recommended, contact times. 

Quaternary ammonium compounds: Commonly used for sanitation of noncritical surfaces, such as floors, furniture, and walls and are also appropriate for disinfecting medical equipment that contacts intact skin4. Also typically used in food service industry. Efficacy can be impacted by water hardness and materials such as cotton and gauze pads. Non-woven spun-lace wipes are recommended for application4. Low corrosion and highly stable. More effective in alkaline than acid solutions. Examples: Alkyl dimethyl benzyl ammonium chlorides; alkyl dimethyl ethylbenzyl ammonium chloride; didecyldimethylammonium chloride.

Application – Whole room and surface disinfectant. Limited use for immersion. Quaternary ammonium compounds are cationic detergents, as well as disinfectants, and as such can be used to remove organic material followed by a second application for disinfection

Equipment Types – Floors, furniture, and walls. Appropriate to use for disinfecting medical equipment that contacts intact skin. Requires post use rinse for any surfaces that will contact food.

Potential Hazards – Considered less toxic than many other disinfectants. Skin and eye irritant. May cause an allergic reaction for some individuals. Possible eye and mucous membrane injuries from splashes or contact with mists8.

Phenolic: Effectiveness reduced by alkaline pH, natural soap, organic material. Can leave a gummy residue. Due to toxicity, a post-use rinse is recommended. Example compound: Thymol.

Application – Surface disinfectant.

Equipment Types – Can be used on laboratory surfaces and floors. Prolonged contact deteriorates rubber.

Potential Hazards – Easily absorbed through the skin and can act as a carrier, drawing other substances through the skin with it. Oral, dermal, and inhalation toxicity. Corrosive. Some phenol-based disinfectants are considered carcinogens. Phenolic compounds are more difficult to rinse from equipment than other disinfectants, resulting in exposures long after disinfection and possible skin/mucous membrane irritation/injury. May cause allergic reaction for some individuals.

Alcohols: Effective range 60-80%. 70% ethanol or isopropanol alone are widely used in laboratories, but the rapid evaporation rate makes achieving the required contact time (typically 5 minutes) on surfaces difficult, especially in biosafety cabinets with additional airflow.

Application – Hand sanitation or for submerging items.

Equipment Types – Safe on metal surfaces and laboratory benches. If used to wipe computer screens or cell phones, it is recommended to spray on cloth instead of directly on the surfaces. Prolonged exposure to alcohol has been known to disrupt adhesives, damage seals, cause certain plastics to swell and harden, which could make them more brittle and prone to break. Does not leave any residue.

Potential Hazards – Highly flammable. Need to eliminate ignition sources. Due to this hazard, alcohols should not be the first choice for surface disinfection. Creates intoxicating fumes.

Reducers: Example compounds: Citric acid; Silver ion/ Citric acid; L-Lactic Acid

Application – Surface disinfection. Citric acid used in combination with alcohols as hand sanitizer. Used in dental procedures, disinfecting dialysis lines, and on farms (hoof & mouth disease).

Equipment Types - Will not harm plastics, glass or metal. All food contact surfaces must be rinsed with water.

Potential Hazards - A severe eye and moderate skin irritant.

There are many products on the market.  Further information on active ingredients can be on the CDC website referenced above, or on the WSU OEHS website: https://research.wayne.edu/oehs/pdf/proper-disinfectants.pdf

*Household bleach, alcohol solutions, or topical hydrogen peroxide solutions: Where possible, EPA approved disinfectants should be used. If you cannot locate an EPA approved disinfectant, then dilutions of unexpired household bleach, 70% alcohol, or 3% hydrogen peroxide solutions are an acceptable alternative.

Cleaning, Disinfecting, or Sanitizing9

Cleaning removes germs, dirt, and impurities from surfaces or objects. Cleaning works by using soap (or detergent) and water to physically remove germs from surfaces. This process does not necessarily kill germs, but by removing them, it lowers their numbers and the risk of spreading infection.

Disinfecting kills germs on surfaces or objects. Disinfecting works by using chemicals to kill germs on surfaces or objects. This process does not necessarily clean dirty surfaces or remove germs, but by killing germs on a surface after cleaning, it can further lower the risk of spreading infection.

Sanitizing lowers the number of germs on surfaces or objects to a safe level, as judged by public health standards or requirements. This process works by either cleaning or disinfecting surfaces or objects to lower the risk of spreading infection.

Best Practices: Cleaning and Disinfecting Workspaces10

  1. Create a plan:  Document the cleaning and disinfecting plan.  Ensure that each staff member understands the cleaning and disinfecting requirements, including how frequently each action must be performed. 
  2. What materials do you have available that target SARS-CoV-2?  SARS-CoV-2 is an enveloped virus.  This is important as a wide range of disinfectants effectively disrupt or strip away the lipid membrane on the outer surface of enveloped viruses. As such, many disinfectants available in your laboratory can be utilized to reduce the spread of SARS-CoV-2.
  3. What Personal Protective Equipment (PPE) is required?  Ensure you evaluate the Safety Data Sheet to determine what PPE is required, and what hazards are present due to the chemical nature of the disinfectant.  Chemicals such as hypochlorites, quaternary ammonium compounds, and hydrogen peroxide can be irritants, caustic or toxic to the user.  Ensure adequate ventilation in the locations used.
  4. Determine what needs to be cleaned/disinfected:  Surfaces that are infrequently touched can be cleaned with soap and water and do not need additional disinfection.  Target frequently touched objects and surfaces for disinfection.  High touch areas involving multiple people are primary targets for cleaning and  disinfecting.
  5. Reduce the items that need to cleaned/disinfected:  What items can be moved into storage to reduce the amount of cleaning required?  Consider removing all soft and porous materials to reduce the challenges associated with cleaning and disinfecting such items.
  6. Evaluate your electronic equipment:  Is the equipment sensitive to chemical exposure?  Can it be immersed?  Is it porous, or absorbent?  It is important to consult with the manufacturer to ensure that you use an approved disinfectant.  Inappropriate use of a disinfectant can void the manufacturer's warranty.  Consider the use of wipe-able covers for electronics. For some devices it is better to apply the disinfectant to a cloth used to wipe the device, instead of spraying directly on the device.
  7. Clean work surfaces or object with soap and water to remove contaminants. Cleaning a surface to remove contaminants is important prior to application of disinfectants.  This is especially important in laboratories where incompatible materials may be present. DO NOT MIX CLEANING SOLUTIONS WITH DISINFECTANTS OR MIX DIFFERENT DISINFECTANTS. This may produce toxic fumes or hazardous reactions.
  • Evaluate the organic content of the materials being treated:  Organic load can impact the effectiveness of a disinfectant.  For example, hypochlorites can be inactivated by organic matter (e.g. blood, soil etc). 
  •  
  • Evaluate the buildup of dirt and debris on surfaces: Layers of grime on a surface reduces contact with microbes that may be present. Similar to organic load, some disinfectants lose effective when they interact with certain materials.
  • Consider any potential adverse chemical reactions:  What else is potentially present on the surfaces/work benches to be cleaned?  How will it react with the disinfectant? 
  1. Contact time matters:  EPA registered disinfectants must only be used in a manner that is consistent with the product labeling.  Follow the instructions for the specific disinfectant selected regarding the types of surfaces that can be effectively treated (e.g. metal, wood, porous vs. non-porous etc.). Surfaces must be kept wet for the full time indicated.  
  2. Store and use disinfectants in a responsible and appropriate manner:  Follow the directions on the label.  This is integral to achieving effective decontamination of work surfaces. 
  3. Do not mix bleach or other cleaning and disinfection products:  Mixing of disinfectants has led to workplace fatalities and must be avoided.

References

  1. CDC Coronavirus Disease 2019 (COVID 19)
  2. Van Doremalen et al. Aerosol and surface stability of HCoV-19 (SARS-CoV-2) compared to SARS-CoV-1. NEJM, 2020
  3. United States Environmental Protection Agency
  4. EPA Label Review Training: Module 2: Parts of the Label
  5. CDC – Chemical Disinfectants
  6. McDonnell G and Russell AD. Antiseptics and Disinfectants: Activity, Action, and Resistance. Clinical Microbiology Reviews, Jan. 1999, p. 147–179.
  7. Guideline for Disinfection and Sterilization in Healthcare Facilities (2008)
  8. Quaternary Ammonium Compounds in Cleaning Products: Health & Safety Information for Health Professionals
  9. CDC - How to Clean and Disinfect Schools to Help Slow the Spread of Flu
  10. CDC Guidance for Cleaning and Disinfecting

For a print only version of this guidance, visit here.