Mineral oil is any of various colorless, odorless, light mixtures of higher alkanes from a mineral source, particularly a distillate of petroleum, as distinct from usually edible vegetable oils. The name 'mineral oil' by itself is imprecise, having been used for many specific oils since 1771. Other names, similarly imprecise, include 'white oil', 'paraffin oil', 'liquid paraffin' (a highly refined medical grade), paraffinum liquidum (Latin), and 'liquid petroleum'. Most often, mineral oil is today a liquid obtained from refining crude oil to make gasoline and other petroleum products. Mineral oils used for lubrication are known specifically as base oils. More generally, mineral oil is a transparent, colorless oil, composed mainly of alkanes and cycloalkanes, related to petroleum jelly. It has a density of around 0.8–0.87 g/cm3 (0.029–0.031 lb/cu in).
Nomenclature Some of the imprecision in the definition of the names used for mineral oil (such as 'white oil') reflects usage by consumers and merchants who did not know, and usually had no need of knowing, the oil's precise chemical makeup. Merriam-Webster states the first use of the term "mineral oil" as being 1771. Prior to the late 19th century, the chemical science to determine the makeup of an oil was unavailable in any case. A similar lexical situation occurred with the term "white metal". "Mineral oil", sold widely and cheaply in the United States, is not sold as such in the United Kingdom. Instead, British pharmacologists use the terms "paraffinum perliquidum" for light mineral oil and "paraffinum liquidum" or "paraffinum subliquidum" for somewhat more viscous varieties. The term "paraffinum liquidum" is often seen on the ingredient lists of baby oil and cosmetics. British aromatherapists commonly use the term "white mineral oil". In lubrication, mineral oils make up Group I, II, and III base oils that are refined from petroleum.
Toxicology The World Health Organization classifies minimally treated mineral oils as carcinogens group 1 known to be carcinogenic to humans; Highly refined oils are classified group 3 as not classifiable as carcinogenic, due to a lack of sufficient evidence. The UK Food Standards Agency (FSA) carried out a risk assessment on the migration of components from printing inks used on carton-board packaging—including mineral oils—into food in 2011, based on the findings of a survey conducted in the same year. The FSA did not identify any specific food safety concerns due to inks. People can be exposed to mineral oil mist in the workplace through inhalation, skin contact, or eye contact. In the United States, the Occupational Safety and Health Administration has set the legal limit for mineral oil mist exposure in the workplace as 5 mg/m3 (0.0022 gr/cu ft) over an 8-hour workday, the National Institute for Occupational Safety and Health has set a recommended exposure limit of 5 mg/m3 (0.0022 gr/cu ft) over an 8-hour workday, with a previous limit of 10 mg/m3 (0.0044 gr/cu ft) for short-term exposure rescinded according to the 2019 Guide to Occupational Exposure Values compiled by the ACGIH. Levels of 2,500 mg/m3 (1.1 gr/cu ft) and higher are indicated as immediately dangerous to life and health. However, current toxicological data does not contain any evidence of irreversible health effects due to short-term exposure at any level; the current value of 2,500 mg/m3 (1.1 gr/cu ft) is indicated as being arbitrary.
Applications
Biomedicine
Laxative
Mineral oil is used as a laxative to alleviate constipation by retaining water in stool and the intestines. Although generally considered safe, as noted above, there is a concern of mist inhalation leading to serious health conditions such as pneumonia. Mineral oil can be administered either orally or rectally. It is sometimes used as a lubricant in enema preparations as most of the ingested material is excreted in the stool rather than being absorbed by the body.
Personal lubricant It is recommended by the American Society for Reproductive Medicine for use as a fertility-preserving vaginal lubrication. However, it is known that oils degrade latex condoms.
Cell culture Mineral oil of special purity is often used as an overlay covering micro drops of culture medium in petri dishes, during the culture of oocytes and embryos in IVF and related procedures. The use of oil presents several advantages over the open culture system: it allows for several oocytes and embryos to be cultured simultaneously, but observed separately, in the same dish; it minimizes concentration and pH changes by preventing evaporation of the medium; it allows for a significant reduction of the medium volume used (as few as 20 μl (0.0012 cu in) per oocyte instead of several milliliters for the batch culture); and it serves as a temperature buffer minimizing thermal shock to the cells while the dish is taken out of the incubator for observation.
Veterinary
Over-the-counter veterinarian-use mineral oil is intended as a mild laxative for pets and livestock. Certain mineral oils are used in livestock vaccines, as an adjuvant to stimulate a cell-mediated immune response to the vaccinating agent. In the poultry industry, plain mineral oil can also be swabbed onto the feet of chickens infected with scaly mites on the shank, toes, and webs. Mineral oil suffocates these tiny parasites. In beekeeping, food grade mineral oil-saturated paper napkins placed in hives are used as a treatment for tracheal and other mites. It is also used along with a cotton swab to remove un-shed skin (ashes) on reptiles such as lizards and snakes.
Cosmetics Mineral oil is a common ingredient in baby lotions, cold creams, ointments, and cosmetics. It is a lightweight inexpensive oil that is odorless and tasteless. It can be used on eyelashes to prevent brittleness and breaking and, in cold cream, is also used to remove creme make-up and temporary tattoos. One of the common concerns regarding the use of mineral oil is its presence on several lists of comedogenic substances. These lists of comedogenic substances were developed many years ago and are frequently quoted in the dermatological literature. The type of highly refined and purified mineral oil found in cosmetic and skincare products is noncomedogenic (does not clog pores).
Mechanical, electrical, and industrial
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