The name mineral oil by itself is imprecise, having been used for many specific oils over the past few centuries. Other names, similarly imprecise, include white oil, paraffin oil, liquid paraffin (a highly refined medical grade), paraffinum liquidum (Latin), and liquid petroleum. Baby oil is a perfumed mineral oil.
Most often, mineral oil is a liquid by-product of refining crude oil to make gasoline and other petroleum products. This type of 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.
Some of the imprecision in the definition of the names (e.g., "mineral oil", "white oil") reflects usage by buyers and sellers who did not know, and usually did not need to care about, the precise chemical makeup. Merriam-Webster states the first use of the term "mineral oil" was 1771. Prior to the late 19th century, the chemical science to determine such makeup was unavailable in any case. A similar lexical situation occurred with the term "white metal".
"Mineral oil", sold widely and cheaply in the US, is not sold as such in Britain. Instead British pharmacologists use the terms "paraffinum perliquidum" for light mineral oil and "paraffinum liquidum" or "paraffinum subliquidum" for somewhat thicker (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 lubricating oils, mineral oil is termed from groups 1 to 2 worldwide and group 3 in certain regions. This is because the high end of group 3 mineral lubricating oils are so pure that they exhibit properties similar to polyalphaolefin - PAO oils (group 4 synthetics).
The World Health Organization classifies untreated or mildly treated mineral oils as group 1 carcinogens to humans; highly refined oils are classified as group 3, meaning that they are not suspected to be carcinogenic, but available information is not sufficient to classify them as harmless.
The UK Food Standards Agency (FSA) carried out a risk assessment on the findings of a survey made in 2011 on risks due to migration of components from printing inks used on carton-board packaging, including mineral oils, into food. The FSA did not identify any specific food safety concerns due to inks.
People can be exposed to mineral oil mist in the workplace by breathing it in, 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 over an 8-hour workday, the National Institute for Occupational Safety and Health has set a recommended exposure limit of 5 mg/m3 over an 8-hour workday, and 10 mg/m3 short-term exposure has been rescinded according to the 2019 Guide to Occupational Exposure Values compiled by the ACGIH. Levels of 2500 mg/m3 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 2500 mg/m3 is indicated as being arbitrary.
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 as an enema. Also, it is sometimes used as a lubricant in enema preparations, because most of the ingested material is excreted in the stool rather than being absorbed by the body.
Mineral oil of special purity is often used as an overlay covering microdrops 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 microlitres per oocyte instead of several millilitres 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.
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.
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).
Mineral oil is used in a variety of industrial/mechanical capacities as a non-conductive coolant or thermal fluid in electric components as it does not conduct electricity and functions to displace air and water. Some examples are in transformers, where it is known as transformer oil, and in high-voltage switchgear, where mineral oil is used as an insulator and as a coolant to disperse switching arcs. The dielectric constant of mineral oil ranges from 2.3 at 50 °C (122 °F) to 2.1 at 200 °C (392 °F).
Mineral oil is used as a lubricant, a cutting fluid, and a jute batching oil.[clarification needed]Spindle oils are light mineral oils used as lubricants in textile industries. Electric space heaters sometimes use mineral oil as a heat transfer oil. Because it is noncompressible, mineral oil is used as a hydraulic fluid in hydraulic machinery and vehicles.
Food grade mineral oil has an E number of E905a, although it has not been approved in food products in the European Union, and incidental amounts in foods are carefully regulated.[dubious ] 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 wooden cutting boards, salad bowls, and utensils. Rubbing a small amount of mineral oil into a wooden kitchen item periodically, will impede absorption of food liquids, and thereby food odors, and ease cleaning. By impeding water absorption, wetting and drying cycles, which can cause cracks or splits in wood, are reduced although some of the mineral oil is picked up by the food and ingested. Outside of the European Union, it is occasionally used in the food industry, particularly for confectionery. In this application, it is typically used for the glossy effect it produces, and to prevent the candy pieces from adhering to each other. It has been discouraged for use in children's foods, though it is still found in many confectioneries, including Swedish Fish. The use of food grade mineral oil is self-limiting because of its laxative effect. The maximum daily intake is calculated to be about 100 mg, of which some 80 mg are contributed from its use on machines in the baking industry.
Mineral oil's ubiquity has led to its use in some niche applications as well. It is used for treating and preserving wooden butcher block counter tops. 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.
Mineral oil is commonly used to create a "wear" effect on new clay poker chips, which can otherwise be accomplished only through prolonged use. Either the chips are placed in mineral oil for a short time, or the oil is applied to each chip then rubbed off. This removes any chalky residue left over from manufacture, and also improve the look and "feel"[clarification needed] of the chips.
It is used as the principal fuel in some types of gel-type scented candles.
It is used for cooling, for example liquid submersion cooling of components in some custom-built computers. Veterinarian-grade mineral oil is inexpensive, and is frequently used by amateur radio operators as coolant in RF dummy loads, as mineral oil is typically used as the insulating and cooling fluid in large electrical equipment such as transformers, see more above.
Mineral oil is burned in specialized "machines" (both manufactured and home-made) to produce a thick white smoke that is then blown into automotive evaporative emissions (EVAP) systems to find leaks.
It is used for polishing alabaster in stonework and lubricating and cleaning pocket knives or food handling tools that use an open bearing, thus needing periodic lubrication. Light mineral oil (paraffinum perliquidum) is used as a honing oil when sharpening edge tools (such as chisels) on abrasive oil stones. Mineral oil USP or light mineral oil can be used as an anti-rust agent for blades.
It is an inexpensive alternative for storing reactive metals (lithium, sodium, etc.).
Horticultural oil is often made of a combination of mineral oil and detergent. It is sprayed on plants to control scale, aphid, and other pest populations by suffocation.
Before the widespread adoption of thermocyclers with heated lids, it was common practice to use mineral oil to overlay polymerase chain reactions in biotechnology to prevent loss of water during heating cycles. It is often used to suspend crystals for use in X-ray crystallography.
Paraffin oil is commonly used to fill Galileo thermometers. Due to paraffin oil's freezing temp being lower than water (approx. 24 °F (-4 °C) or -4 °C), this makes them less susceptible to freezing during shipment or when stored in a cold environment.
Gel candles use liquids such as mineral oil, terpene-type chemicals, or modified hydrocarbons as their primary fuel.