disinfectant disinfectant a disinfectant is a chemical substance or compound used to inactivate or destroy microorganisms on inert surfaces. disinfection does not necessarily kill all microorganisms, especially resistant bacterial spores; it is less effective than sterilization, which is an extreme physical or chemical process that kills all types of life. disinfectants are generally distinguished from other antimicrobial agents such as antibiotics, which destroy microorganisms within the body, and antiseptics, which destroy microorganisms on living tissue. disinfectants are also different from biocides—the latter are intended to destroy all forms of life, not just microorganisms. disinfectants work by destroying the cell wall of microbes or interfering with their metabolism. it is also a form of decontamination, and can be defined as the process whereby physical or chemical methods are used to reduce the amount of pathogenic microorganisms on a surface. disinfection of a floor using disinfectant liquid applied using a mop. levels of resistance of microbes to disinfectants. disinfectants can also be used to destroy microorganisms on the skin and mucous membrane, as in the medical dictionary historically the word simply meant that it destroys microbes. sanitizers are substances that simultaneously clean and disinfect. disinfectants kill more germs than sanitizers. disinfectants are frequently used in hospitals, dental surgeries, kitchens, and bathrooms to kill infectious organisms. sanitizers are mild compared to disinfectants and are used majorly to clean things that are in human contact whereas disinfectants are concentrated and are used to clean surfaces like floors and building premises. bacterial endospores are most resistant to disinfectants, but some fungi, viruses and bacteria also possess some resistance. disinfectants are used to rapidly kill bacteria. they kill off the bacteria by causing the proteins to become damaged and the outer layers of the bacteria cell to rupture. the dna material subsequently leaks out. in wastewater treatment, a disinfection step with chlorine, ultra-violet (uv) radiation or ozonation can be included as tertiary treatment to remove pathogens from wastewater, for example if it is to be discharged to a river or the sea where there body contact immersion recreations is practiced (europe) or reused to irrigate golf courses (us). an alternative term used in the sanitation sector for disinfection of waste streams, sewage sludge or fecal sludge is sanitisation or sanitization. definitions the australian therapeutic goods order no. 54 defines several grades of disinfectant as will be used below. sterilant sterilant means a chemical agent which is used to sterilize critical medical devices or medical instruments. a sterilant kills all micro-organisms with the result that the sterility assurance level of a microbial survivor is less than 10^-6. sterilant gases are not within this scope. low level disinfectant low level disinfectant means a disinfectant that rapidly kills most vegetative bacteria as well as medium-sized lipid containing viruses, when used according to labelling. it cannot be relied upon to destroy, within a practical period, bacterial endospores, mycobacteria, fungi, or all small nonlipid viruses. intermediate level disinfectant intermediate level disinfectant means a disinfectant that kills all microbial pathogens except bacterial endospores, when used as recommended by the manufacturer. it is bactericidal, tuberculocidal, fungicidal (against asexual spores but not necessarily dried chlamydospores or sexual spores), and virucidal. high level disinfectant high level disinfectant means a disinfectant that kills all microbial pathogens, except large numbers of bacterial endospores when used as recommended by its manufacturer. instrument grade instrument grade disinfectant means: a disinfectant which is used to reprocess reusable therapeutic devices; and when associated with the words “low”, “intermediate” or “high” means “low”, “intermediate” or “high” level disinfectant respectively. hospital grade hospital grade disinfectant means a disinfectant that is suitable for general purpose disinfection of building and fitting surfaces, and purposes not involving instruments or surfaces likely to come into contact with broken skin: in premises used for: the investigation or treatment of a disease, ailment or injury; or procedures that are carried out involving the penetration of the human skin; or, in connection with: the business of beauty therapy or hairdressing; or the practice of podiatry; but does not include : instrument grade disinfectants; or sterilant; or an antibacterial clothes preparation; or a sanitary fluid; or a sanitary powder; or a sanitiser. household/commercial grade household/commercial grade disinfectant means a disinfectant that is suitable for general purpose disinfection of building or fitting surfaces, and for other purposes, in premises or involving procedures other than those specified for a hospital-grade disinfectant, but is not: an antibacterial clothes preparation; or a sanitary fluid; or a sanitary powder; or a sanitiser measurements of effectiveness one way to compare disinfectants is to compare how well they do against a known disinfectant and rate them accordingly. phenol is the standard, and the corresponding rating system is called the "phenol coefficient". the disinfectant to be tested is compared with phenol on a standard microbe (usually salmonella typhi or staphylococcus aureus). disinfectants that are more effective than phenol have a coefficient > 1. those that are less effective have a coefficient < 1. the standard european approach for disinfectant validation consists of a basic suspension test, a quantitative suspension test (with low and high levels of organic material added to act as ‘interfering substances’) and a two part simulated-use surface test. a less specific measurement of effectiveness is the united states environmental protection agency (epa) classification into either high, intermediate or low levels of disinfection. "high-level disinfection kills all organisms, except high levels of bacterial spores" and is done with a chemical germicide marketed as a sterilant by the u.s. food and drug administration (fda). "intermediate-level disinfection kills mycobacteria, most viruses, and bacteria with a chemical germicide registered as a 'tuberculocide' by the environmental protection agency. low-level disinfection kills some viruses and bacteria with a chemical germicide registered as a hospital disinfectant by the epa." an alternative assessment is to measure the minimum inhibitory concentrations (mics) of disinfectants against selected (and representative) microbial species, such as through the use of microbroth dilution testing. however, those methods are obtained at standard inoculum levels without considering the inoculum effect. more informative methods are nowadays in demand to determine the minimum disinfectant dose as a function of the density of the target microbial species. properties a perfect disinfectant would also offer complete and full microbiological sterilisation, without harming humans and useful form of life, be inexpensive, and noncorrosive. however, most disinfectants are also, by nature, potentially harmful (even toxic) to humans or animals. most modern household disinfectants contain denatonium, an exceptionally bitter substance added to discourage ingestion, as a safety measure. those that are used indoors should never be mixed with other cleaning products as chemical reactions can occur. the choice of disinfectant to be used depends on the particular situation. some disinfectants have a wide spectrum (kill many different types of microorganisms), while others kill a smaller range of disease-causing organisms but are preferred for other properties (they may be non-corrosive, non-toxic, or inexpensive). there are arguments for creating or maintaining conditions that are not conducive to bacterial survival and multiplication, rather than attempting to kill them with chemicals. bacteria can increase in number very quickly, which enables them to evolve rapidly. should some bacteria survive a chemical attack, they give rise to new generations composed completely of bacteria that have resistance to the particular chemical used. under a sustained chemical attack, the surviving bacteria in successive generations are increasingly resistant to the chemical used, and ultimately the chemical is rendered ineffective. for this reason, some question the wisdom of impregnating cloths, cutting boards and worktops in the home with bactericidal chemicals. types air disinfectants air disinfectants are typically chemical substances capable of disinfecting microorganisms suspended in the air. disinfectants are generally assumed to be limited to use on surfaces, but that is not the case. in 1928, a study found that airborne microorganisms could be killed using mists of dilute bleach. an air disinfectant must be dispersed either as an aerosol or vapour at a sufficient concentration in the air to cause the number of viable infectious microorganisms to be significantly reduced. in the 1940s and early 1950s, further studies showed inactivation of diverse bacteria, influenza virus, and penicillium chrysogenum (previously p. notatum) mold fungus using various glycols, principally propylene glycol and triethylene glycol. in principle, these chemical substances are ideal air disinfectants because they have both high lethality to microorganisms and low mammalian toxicity. although glycols are effective air disinfectants in controlled laboratory environments, it is more difficult to use them effectively in real-world environments because the disinfection of air is sensitive to continuous action. continuous action in real-world environments with outside air exchanges at door, hvac, and window interfaces, and in the presence of materials that adsorb and remove glycols from the air, poses engineering challenges that are not critical for surface disinfection. the engineering challenge associated with creating a sufficient concentration of the glycol vapours in the air have not to date been sufficiently addressed. alcohols automatic hand sanitizer in tomaszów mazowiecki, poland