an unstable emulsion results water-in-oil emulsions are less common in food, but still exist: butter – an emulsion of water in butterfat margarine other foods can be turned into products similar to emulsions, for example meat emulsion is a suspension of meat in liquid that is similar to true emulsions. in health care in pharmaceutics, hairstyling, personal hygiene, and cosmetics, emulsions are frequently used. these are usually oil and water emulsions but dispersed, and which is continuous depends in many cases on the pharmaceutical formulation. these emulsions may be called creams, ointments, liniments (balms), pastes, films, or liquids, depending mostly on their oil-to-water ratios, other additives, and their intended route of administration. the first 5 are topical dosage forms, and may be used on the surface of the skin, transdermally, ophthalmically, rectally, or vaginally. a highly liquid emulsion may also be used orally, or may be injected in some cases. microemulsions are used to deliver vaccines and kill microbes. typical emulsions used in these techniques are nanoemulsions of soybean oil, with particles that are 400–600 nm in diameter. the process is not chemical, as with other types of antimicrobial treatments, but mechanical. the smaller the droplet the greater the surface tension and thus the greater the force required to merge with other lipids. the oil is emulsified with detergents using a high-shear mixer to stabilize the emulsion so, when they encounter the lipids in the cell membrane or envelope of bacteria or viruses, they force the lipids to merge with themselves. on a mass scale, in effect this disintegrates the membrane and kills the pathogen. the soybean oil emulsion does not harm normal human cells, or the cells of most other higher organisms, with the exceptions of sperm cells and blood cells, which are vulnerable to nanoemulsions due to the peculiarities of their membrane structures. for this reason, these nanoemulsions are not currently used intravenously (iv). the most effective application of this type of nanoemulsion is for the disinfection of surfaces. some types of nanoemulsions have been shown to effectively destroy hiv-1 and tuberculosis pathogens on non-porous surfaces. applications in pharmaceutical industry oral drug delivery: emulsions may provide an efficient means of administering drugs that are poorly soluble or have low bioavailability or dissolution rates, increasing both dissolution rates and absorption to increase bioavailability and improve bioavailability. by increasing surface area provided by an emulsion, dissolution rates and absorption rates of drugs are increased, improving their bioavailability. topical formulations: emulsions are widely utilized as bases for topical drug delivery formulations such as creams, lotions and ointments. their incorporation allows lipophilic as well as hydrophilic drugs to be mixed together for maximum skin penetration and permeation of active ingredients. parenteral drug delivery: emulsions serve as carriers for intravenous or intramuscular administration of drugs, solubilizing lipophilic ones while protecting from degradation and decreasing injection site irritation. examples include propofol as a widely used anesthetic and lipid-based solutions used for total parenteral nutrition delivery. ocular drug delivery: emulsions can be used to formulate eye drops and other ocular drug delivery systems, increasing drug retention time in the eye and permeating through corneal barriers more easily while providing sustained release of active ingredients and thus increasing therapeutic efficacy. nasal and pulmonary drug delivery: emulsions can be an ideal vehicle for creating nasal sprays and inhalable drug products, enhancing drug absorption through nasal and pulmonary mucosa while providing sustained release with reduced local irritation. vaccine adjuvants: emulsions can serve as vaccine adjuvants by strengthening immune responses against specific antigens. emulsions can enhance antigen solubility and uptake by immune cells while simultaneously providing controlled release, amplifying an immunological response and thus amplifying its effect. taste masking: emulsions can be used to encase bitter or otherwise unpleasant-tasting drugs, masking their taste and increasing patient compliance - particularly with pediatric formulations. cosmeceuticals: emulsions are widely utilized in cosmeceuticals products that combine cosmetic and pharmaceutical properties. these emulsions act as carriers for active ingredients like vitamins, antioxidants and skin lightening agents to provide improved skin penetration and increased stability. in firefighting emulsifying agents are effective at extinguishing fires on small, thin-layer spills of flammable liquids (class b fires). such agents encapsulate the fuel in a fuel-water emulsion, thereby trapping the flammable vapors in the water phase. this emulsion is achieved by applying an aqueous surfactant solution to the fuel through a high-pressure nozzle. emulsifiers are not effective at extinguishing large fires involving bulk/deep liquid fuels, because the amount of emulsifier agent needed for extinguishment is a function of the volume of the fuel, whereas other agents such as aqueous film-forming foam need cover only the surface of the fuel to achieve vapor mitigation. chemical synthesis emulsions are used to manufacture polymer dispersions – polymer production in an emulsion 'phase' has a number of process advantages, including prevention of coagulation of product. products produced by such polymerisations may be used as the emulsions – products including primary components for glues and paints. synthetic latexes (rubbers) are also produced by this process.