Mineral oil is any of various colorless, odorless, light mixtures ofhigher alkanes from amineral source, particularly a distillate ofpetroleum,[1] as distinct from usually ediblevegetable 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 refinedmedical grade),paraffinum liquidum (Latin), and 'liquid petroleum'.
Most often, mineral oil is a liquid obtained fromrefiningcrude oil to makegasoline and otherpetroleum products. Mineral oils used for lubrication are known specifically asbase oils. More generally, mineral oil is atransparent, colorless oil, composed mainly ofalkanes[2] andcycloalkanes, related topetroleum jelly. It has adensity of around 0.8–0.87 g/cm3 (0.029–0.031 lb/cu in).[3]
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.[4] 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 andcosmetics. Britisharomatherapists commonly use the term "white mineral oil". Inlubrication, mineral oils make up Group I, II, and III base oils that are refined from petroleum.[5][6]
TheWorld Health Organization classifies minimally treated mineral oils ascarcinogens group 1 known to be carcinogenic to humans;[7] Highly refined oils are classified group 3 as not classifiable as carcinogenic, due to a lack of sufficient evidence.[8]
The UKFood 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.[9]
People can be exposed to mineral oil mist in the workplace through inhalation, skin contact, or eye contact. In the United States, theOccupational Safety and Health Administration has set thelegal limit for mineral oil mist exposure in the workplace as 5 mg/m3 (0.0022 gr/cu ft) over an 8-hour workday, theNational Institute for Occupational Safety and Health has set arecommended 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 theACGIH. Levels of 2,500 mg/m3 (1.1 gr/cu ft) and higher are indicated asimmediately dangerous to life and health. However, current toxicological data[which?][whose?] 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.[10]
Mineral oil is used as alaxative to alleviateconstipation by retaining water instool and theintestines.[11] Although generally considered safe, as noted above, there is a concern of mist inhalation leading to serious health conditions such aspneumonia.[12]
Mineral oil can be administered either orally[13] or rectally.[14] It is sometimes used as a lubricant inenema preparations as most of the ingested material is excreted in the stool rather than being absorbed by the body.[15]
It is recommended by theAmerican Society for Reproductive Medicine for use as a fertility-preservingvaginal lubrication.[16] However, it is known that oils degradelatex condoms.[17]
Mineral oil of special purity is often used as an overlay covering micro drops ofculture medium inpetri dishes, during the culture of oocytes and embryos inIVF 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.
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Over-the-counterveterinarian-use mineral oil is intended as a mild laxative for pets and livestock.[18] Certain mineral oils are used in livestockvaccines, as anadjuvant to stimulate a cell-mediated immune response to the vaccinating agent. In thepoultry industry, plain mineral oil can also be swabbed onto the feet of chickens infected withscaly mites on the shank, toes, and webs. Mineral oil suffocates these tiny parasites.[19] Inbeekeeping, food grade mineral oil-saturated paper napkins placed in hives are used as a treatment for tracheal and othermites. It is also used along with a cotton swab to remove un-shed skin (ashes) on reptiles such as lizards and snakes.
Mineral oil is a common ingredient inbaby lotions,cold creams,ointments, and cosmetics. It is a lightweight inexpensive oil that is odorless and tasteless. It can be used oneyelashes to prevent brittleness and breaking and, incold cream, is also used to remove creme make-up andtemporary tattoos. One of the common concerns regarding the use of mineral oil is its presence on several lists ofcomedogenic substances.[citation needed] 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).[20]
Mineral oil is used in a variety of industrial/mechanical capacities as a non-conductivecoolant or thermal fluid in electric components, as it does not conduct electricity and functions to displace air and water. Some examples are intransformers, where it is known astransformer oil, and in high-voltageswitchgear, where mineral oil is used as an insulator and coolant to disperse switching arcs.[21] Because it is noncompressible, mineral oil is used as ahydraulic fluid inhydraulic machinery and vehicles.
Thedielectric constant of mineral oil ranges from 2.3 at 50 °C (122 °F) to 2.1 at 200 °C (392 °F).[22]Electric space heaters sometimes use mineral oil as aheat transfer oil. Lubricants used for olderrefrigerator andair conditioningcompressors are based on mineral oil, especially those usingR-22refrigerant.
Mineral oil is used as alubricant, acutting fluid, and as a conditioning oil forjute fibres selected fortextile production, a process known as 'jute batching'.[23]Spindle oils are light mineral oils used as lubricants intextile industries.
An often-cited limitation of mineral oil is that it is poorly biodegradable; in some applications,vegetable oils such ascottonseed oil orrapeseed oil may be used instead.[24]
Because of its properties that prevent water absorption, combined with its lack of flavor and odor, food grade mineral oil is a popular preservative for woodencutting boards, countertops,salad bowls, andutensils. Periodically rubbing a small amount of mineral oil into a wooden kitchen item impedes absorption of food liquids, and thereby food odors, easing the process of hygienically cleaning wooden utensils and equipment. The use of mineral oil to impede water absorption can also prevent cracks and splits from forming in wooden utensils due to wetting and drying cycles. However, some of the mineral oil used on these items, if in contact with food, will be picked up by it and therefore ingested.[citation needed]
Mineral oil is occasionally used in the food industry, particularly forconfectionery. In this application, it is typically used for the glossy effect it produces, and to prevent the candy pieces from adhering to each other, such as inSwedish Fish.[25] The use of food grade mineral oil is self-limiting because of its laxative effect, and is not considered a risk in food for any age class.[26] The maximum daily intake is calculated to be about 100 mg (1.5 gr), of which some 80 mg (1.2 gr) are contributed from its use on machines in the baking industry.[15]
Mineral oil, under various names, is one of the most widely usedinsecticides.[27] SeeHorticultural oil.
Mineral oil's ubiquity has led to its use in some niche applications as well:
Gel candles use liquids such as mineral oil, terpene-type chemicals, or modified hydrocarbons as their primary fuel.
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