In Part 2 of our“Ask the Experts” series, Peter Teska, Global Prevention Application Expert at Diversey, tackles some more pressing questions from our members. Read the full Q&A below.
What is disinfectant surface dwell/contact time and why it is critical to achieving effective disinfection?
“Contact time” or “wet surface contact time” is the amount of time the entire surface stays visibly wet after disinfectant is applied to a hard non-porous surface. This concept is important in understanding how to disinfect properly because several studies have specifically investigated this question and shown that once a surface with disinfectant is dry, there is minimal additional efficacy, regardless of the disinfectant active. Thus the efficacy primarily occurs while the surface is wet and to achieve the efficacy claimed on a product label, the surface must maintain wetness for the full contact time.
What are the fundamental differences between cleaning, sanitizing and disinfecting?
These words describe related, but different things. Cleaning is the removal of soil, which is likely to remove some amount of pathogenic microorganisms, but makes no claim of specific levels of microorganism removal. As a result, cleaning is a commonly used hygiene term, but not a regulatory term, which means it does not have a specific regulatory definition. Sanitizing and disinfection are regulatory terms, and thus have specific regulatory definitions of efficacy. Sanitizing refers to a specific level of reduction of vegetative bacteria, but makes no claims about reductions of viruses, fungi, bacterial spores, or mycobacteria. Disinfection refers to a specific level of reduction of vegetative bacteria, and typically a higher level than sanitizing, but also allows for claims against viruses, fungi, bacterial spores, and mycobacteria. Using a disinfectant is common in environments where a wide range of different types of pathogenic microorganisms may be present, such as a hospital, school, airport, or hotel. Using a sanitizer is most commonly associated with food contact surfaces, such as in a restaurant, kitchen, or food retail setting, but many countries also allow for non-food contact sanitizer claims as well, which is a reduction in bacteria levels on non-food contact surfaces.
Do you know the difference between a ‘hospital-grade’ disinfectant and a limited or general disinfectant?
These are regulatory terms used in the US, but less used in other countries. The term “hospital grade” is no longer commonly used in the US and is being replaced with “hospital use” or “healthcare use” to indicate it is appropriate for healthcare facilities. Limited and general disinfectants are regulatory terms used for disinfectants that show some ability to kill vegetative bacteria, but are not as capable of broad-spectrum efficacy. Since broad spectrum disinfectants are capable of killing or inactivating microorganisms in many classes, they are preferred over limited or general disinfectants.
How does the disinfectant regulatory landscape vary across different countries and regions?
All countries have some regulation of pesticidal products (products that make claims of killing other organisms). The main differences have to do in how claims are allowed to be made about disinfectants, the data required to be provided to the government prior to manufacture, and the testing methods required to be used to generate the data. A few countries do not actually register a disinfectant, but require that the same type of data be generated and maintained by a company, but this is relatively rare. The two main pathways for registration are the European requirements and the US requirements. Most other countries will accept one or both of these data packages. The data package for a disinfectant registration requires chemistry data, toxicity data, and efficacy data. While the test methods used in the US and EU are different, they provide the same type of information. Other countries (outside the EU and US) will generally accept this data as part of a registration package, but may require some additional testing or repeated testing done in the country.
How can business owners effectively implement disinfection solutions in order to achieve more efficiency and lower cost?
Understanding the drivers of cost should be the starting point. Products that are simpler to use, require less training, or less labor to use may provide lower overall operating costs. When evaluating operating costs, ensure that all relevant costs are considered. As examples, launderable wiping cloths may have a cost associated with commercial laundering, but also costs associated with transportation, sorting, and allocation to the work teams. Alternative programs that use prewetted disposable cloths may reduce operating costs for some facilities, but may be more expensive for others. Another comparison may be between programs that use on-site and off-site laundering which should track the cost of chemicals used for laundering and costs associated with the washing machine, water, sewer, electricity, and the value of the space for the laundering operation. In some circumstances on-site laundering may be more cost effective and in others, off-site laundering may be a better option. Products that are easier for workers to use may result in higher compliance and better hygiene outcomes. Comparisons of the various options should be as “apples to apples” as possible by including all relevant costs and performance metrics. Lastly, hygiene outcomes may be of varying importance to facilities. Knowing how to demonstrate improved hygiene outcomes, such as by monitoring cleaning compliance, using ATP or microbial swabbing to provide a measurable hygiene outcome will matter to some facilities more than others. When performing cleaning for contracts with specific hygiene outcomes, it is important to be able to validate the hygiene level. Having ongoing programs that measure hygiene make it easier to understand the costs needed to achieve a certain hygiene level.
An effective disinfection program will help not only reduce the spread of COVID-19, but also the spread of infections from influenza to the common cold, MRSA, Norovirus and more. Can you speak to the importance of how cleaning services help to lower the frequency of these common illnesses in the workplace through an effective disinfection program?
Pathogenic organisms can be spread many ways. The classic model is to consider contact, droplet, and airborne transmission. Contact transmission can be skin to skin contact with another person (direct contact) or person to surface to person (indirect contact). Droplet transmission refers to small respiratory droplets (i.e. >5 microns) and close contact (<2 meters). Airborne refers to small respiratory droplets but over larger distances since small droplets can stay airborne for longer periods of time. In most cases pathogens are not transmitted via one route, but can be transmitted via multiple routes at the same time. Transmission via surfaces (indirect contact) occurs frequently and is more common with certain pathogens than others. Because measuring transmission via a specific route is incredibly complicated, it is rarely possible to determine the portion of transmission that occurred via any given mode after an outbreak. While generally droplet transmission is the most common route of transmission for respiratory viruses, such as SARS-CoV-2 and Influenza, contact transmission does occur, just less frequently. For bacteria such as Staphylococcus aureus, they are most commonly transmitted via direct and indirect contact, but can be transmitted via droplets in certain instances. As a result, interventions are designed to interrupt multiple potential modes simultaneously. Thus cleaning and disinfecting surfaces may have a lesser impact on respiratory virus transmission, but more impact in preventing transmission of E. coli. Since these organisms are invisible to the naked eye on surfaces, we generally assume there is some potential for transmission of a wide range of pathogens on all surfaces, prioritizing those that receive the most hand contact as likely to be the highest risk. While the risk of any specific hand to surface contact may be low risk for transmission of a pathogen, the cumulative risk for a facility based on traffic and the number of hand to surface contacts that occur each day is substantial and needs to be addressed in part by an environmental hygiene program of effective cleaning and disinfection of surfaces.