Disinfectants and sanitizers
Disinfectants and sanitizers are essential antimicrobial agents used for reducing harmful microorganisms and preventing the spread of infectious diseases. A disinfectant is defined as a substance that destroys pathogens, but it does not eliminate all viruses or bacterial spores. In contrast, a sanitizer reduces harmful microorganisms to levels that are not considered infectious. Both processes require that surfaces be cleaned of soil and organic matter for effective action. The U.S. Environmental Protection Agency (EPA) regulates these products, categorizing them into disinfectants, sanitizers, sterilizers, and antiseptics.
Effective disinfectants must achieve at least a 99.999% reduction in pathogenic bacteria within a specific timeframe, while sanitizers must accomplish similar reductions within a much shorter period, often around 30 seconds. Various chemical agents, such as alcohols, chlorine, and hydrogen peroxide, are commonly used, functioning primarily through oxidization to disrupt bacterial cell structures. Historically, advancements in sanitation practices significantly contributed to the decrease in mortality rates linked to infectious diseases, particularly in the late 19th and early 20th centuries.
Despite progress in developed countries, many in the developing world continue to lack access to safe drinking water and basic sanitation. Efforts by the World Health Organization aim to address these disparities, emphasizing the importance of clean water and sanitation as critical components of public health initiatives worldwide.
Disinfectants and sanitizers
Definition
Disinfectants and sanitizers are antimicrobial agents. A “disinfectant” destroys pathogens (disease-causing microorganisms, such as bacteria) but not spores and not all viruses. A “sanitizer” reduces the number of harmful microorganisms, or germs, so that they are not an infectious hazard. Disinfection and sanitization are effective only if a surface area is clean. “Clean” means that a surface has been cleared of soil, dust, organic matter (such as blood or stool), and microorganisms. Cleaning usually can remove large amounts of harmful microorganisms, but it usually does not kill them and does not disinfect or sanitize surfaces.
According to industry standards, a disinfectant must be capable of reducing the level of pathogenic bacteria by 99.999 percent during a time frame greater than five but less than ten minutes under conditions of the Association of Official Agricultural Chemists (AOAC) Use-Dilution Test. A disinfectant destroys all pathogens on a surface or object. Disinfectant products or processes can be ranked as low, medium, or high level. A sanitizer must reduce the level of harmful microorganisms in a specific bacterial test population 99.999 percent (in a process known as a 5-log reduction) within thirty seconds under conditions of the AOAC Germicidal and Detergent Sanitizers Test (GDS).
One substance may work both as a sanitizer and a disinfectant. For example, an iodophor, when used at 25 ppm (parts per million of available iodine), is a sanitizer. However, that same product, when applied at 75 ppm, is a disinfectant. After using the sanitizer, which kills 99.999 percent of bacteria, five thousand bacteria per square foot would remain. These remaining microorganisms reproduce by splitting into two every fifteen minutes. The result is that those five thousand bacteria per square foot have now become 1 million bacteria per square foot within, for example, five hours.
The US Environmental Protection Agency (EPA) is the governing body for antimicrobials. It places antimicrobials into four categories: sterilizers, disinfectants, sanitizers, and antiseptics and germicides. A sterilizer is equipment used in medical procedures. Cleaning professionals are concerned only with disinfectants and sanitizers, which are chemical antimicrobial agents, in contrast to physical antimicrobial agents, such as heat and radiation. Antiseptics and germicides are for use on living beings and are governed by the US Food and Drug Administration (FDA). A sanitizer may be called an antiseptic when it is used on tissue. (Antiseptics are safe to use in this case because they do not have the same killing power as disinfectants.)
Development of Sanitizers and Disinfectants
Infection control was pioneered by hospitals in the nineteenth century. Out of the filth, disease, and poverty of the early nineteenth century came sanitary reform. One of the more significant contributors to the health revolution was the technological, sociological, and environmental phenomenon now known as the sanitary era or the public health campaign. The goal of this campaign was to destroy all possible harmful microorganisms.
Health officials believed it was practical to allow a minimum of ten minutes of contact time with a sanitizer or disinfectant to accomplish this objective. As a result, most disinfectant tests were developed to ascertain whether any bacteria could survive exactly ten minutes of contact. When contact times that are significantly less than ten minutes are allowed, it becomes difficult to get a meaningful result from the Use-Dilution Test.
In food service and public-health-related industries, interest in antimicrobials appeared much later than it did in hospitals. Conditions of use were different, so tests based on ten minutes of contact were not practical. In many cases, thirty seconds is about the maximum time one can realistically expect for contact in food and drink service (such as when a bartender washes a glass).
Because it is not realistic to expect a complete kill in thirty seconds, the GDS test was developed to count microbes. (The Use-Dilution Test, in contrast, indicates the presence of bacteria but yields no counts.) Experts figured that it was possible to get, in thirty seconds, a 99.999 percent reduction in the amount of bacteria with the use of practical agents (such as detergents).
Common Mechanism of Action
A wide range of substances are used as disinfectants. These include alcohols, aldehydes, hydrogen peroxide, iodine, and potassium permanganate solution. Bromine and chlorine are the most common disinfectants and sanitizers for drinking and recreational waters.
The most widely used disinfectants and sanitizers are powerful oxidizers, which means that the atoms of these elements can accept electrons or hydrogen atoms, or both. Hydrogen peroxide, bromine, and chlorine compounds oxidize the complex molecules present on the surface of bacteria, causing their cell walls and cell membranes to disrupt. The proteins on the surface become irreversibly damaged and start to stick together, forming clumps. This happens quickly: A strong solution of sodium hypochlorite (NaOCl, also known as household bleach) solution that is used to disinfect a toilet, for example, kills bacteria within seconds. The bacterial cell cannot respond to the damage quickly enough, and the whole cell simply splits open and dies.
Later research has shown that bacteria do have some capacity to resist an attack by bleach. Contact with hypochlorous acid was found to switch on a gene in some bacteria. This gene is part of the pathway that bugs use to cope with heat stress and the bleach-like substances that cells of the immune system produce to fight infection. If the concentration of bleach solution is low, bacteria with genes that resist this sort of cellular attack might survive.
Impact
It has been claimed that the major decline in mortality in the late nineteenth and early twentieth centuries resulted from innovations in environmental sanitation. About one century later, in 1997, Life magazine considered drinking water chlorination and filtration to be “probably the most significant public health advancement[s] of the millennium.”
Modern hospital disinfectants must show efficacy in eliminating three primary organisms: Staphylococcus aureus, Salmonella, and Pseudomonas aeruginosa. However, hospital administrations generally require disinfectants with even more efficacy.
Many people in developed countries have grown to accept reduced rates of illness as the norm, and outbreaks that once would have been accepted as an unavoidable part of life are now considered crises of public health that require swift and decisive interventions. However, much of the developing world has yet to reap the benefits. According to the World Health Organization (WHO), in 2022, about 27 percent of people globally (2.2 billion people) lived with no source of safe drinking water, and 43 percent (3.5 billion people) lacked safely managed sanitation. Additionally, 25 percent of the global population (2.0 billion people) did not have access at home to a handwashing facility with soap and water.
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