Mineral oils are colourless, almost tasteless, water-insoluble, oily liquids. They are complex hydrocarbon mixtures derived from crude oil. Mineral oils are soluble in many organic solvents (e.g., benzene, chloroform, carbon disulfide, diethyl ether and petroleum ether). They are incompatible with strong oxidisers (e.g., nitric acid or concentrated hydrogen peroxide).
There are many types of mineral oils. To avoid confusion, the Chemical Abstracts Service (CAS) has assigned unique registry numbers to mineral oil types. When information in the article refers a mineral oil type, the type's CAS number will be used to indicate which mineral oil is being referred to. Some common mineral oil types include nujol oil (8012-95-1), liquid paraffin or deodorised kerosene (8020-83-5), white mineral oil (8042-47-5) and hydrotreated middle petroleum distillates (64742-46-7).
White Mineral Oils (8042-47-5)
White mineral oils are practically odourless. They are saturated hydrocarbons having carbon numbers mostly from C15 to C50 and come in heavy medicinal grade, light medicinal grade and technical grade. White mineral oils range from non-irritating to mildly irritating to eyes and skin. Medicinal grade oils have a flash point of 185 to 122 degrees Celsius (365 to 430 degrees Fahrenheit), and technical grade oils have a flash point of 171 to 185 degrees C (340 to 365 degrees F). They can accumulate a static charge by agitation or when poured and can float on water. The boiling-point range for white mineral oil is 218 to 643 degrees C (217 to 642 degrees C).
Liquid Paraffin (8020-83-5)
Liquid paraffin is mildly toxic by ingestion and is a skin and eye irritant. It has a flash point of 195 degrees C (195 degrees C), an autoignition temperature of 338 degrees C (338 degrees C) and a density of 0.845.
Nujol Oils (8012-95-1)
Nujol oils are skin and eye irritants. Inhalation of nujol oils can cause lipid pneumonia, with coughing and pulmonary oedema. Ingestion of them can cause loose bowel movements, abdominal pain, diarrhoea, nausea and vomiting. They can cause can cause dermatitis, inflammation of the hair follicles and acne after prolonged or repeated skin exposure. The flash point for nujol oils ranges from 77 to 135 degrees C (170 to 275 degrees F); the autoignition temperature ranges from 260 to 371 degrees C (500 to 700 degrees F). Nujol oils with a density of 0.83 to 0.86 are considered light, and those of 0.875 to 0.905 are considered heavy.
Hydrotreated Middle Petroleum Distillates (64742-46-7)
Inhalation of mists or sprays of hydrotreated middle petroleum distillates can cause headache, nausea, ringing in the ears and weakness. The flash point for them ranges from 129 to 135 degrees C (264 to 275 degrees F); the boiling point, from 256 to 295 degrees C (492 to 563 degrees F).
Untreated and mildly treated mineral oils are considered human carcinogens by the state of California, the U.S. National Toxicology Program and the International Agency for Research on Cancer. Highly refined mineral oils are considered unclassifiable as to carcinogenicity in humans by the IARC. In the European Union, hydrotreated middle petroleum distillates are classified as carcinogens unless the full refining history is known and it can be shown that the substance an oil is produced from is not a carcinogen.