Castor oil is a vegetable oil obtained from the castor bean (technically castor seed as the castor plant, Ricinus communis, is not a member of the bean family). Castor oil (CAS number 8001-79-4) is a colorless to very pale yellow liquid with mild or no odor or taste. Its boiling point is 313 °C (595 °F) and its density is 961 kg·m−3. It is a triglyceride in which approximately ninety percent of fatty acid chains are ricinoleic acid. Oleic and linoleic acids are the other significant components.
Ricinoleic acid, a monounsaturated, 18-carbon fatty acid, is unusual in that it has a hydroxyl functional group on the twelfth carbon. This functional group causes ricinoleic acid (and castor oil) to be unusually polar, and also allows chemical derivatization that is not practical with most other seed oils. It is the hydroxyl group which makes castor oil and ricinoleic acid valuable as chemical feedstocks. Compared to other seed oils which lack the hydroxyl group, castor oil commands a higher price. As an example, in July 2007 Indian castor oil sold for about US$0.90 per kilogram (US$0.41 per pound) while U.S. soybean, sunflower and canola oil sold for about US$0.30 per kilogram (US$0.14 per pound).
Castor oil and its derivatives have applications in the manufacturing of soaps, lubricants, hydraulic and brake fluids, paints, dyes, coatings, inks, cold resistant plastics, waxes and polishes, nylon, pharmaceuticals and perfumes.
Sulfonated castor oil, also called sulfated castor oil, or Turkey Red Oil, is the only oil that completely disperses in water. It is made by adding sulfuric acid to pure castor oil. This allows easy use for making bath oil products. It was the first synthetic detergent after ordinary soap. It is used in formulating lubricants, softeners, and dyeing assistants.
The castor seed contains ricin, a toxic protein removed by cold pressing and filtering. However, harvesting castor beans is not without risk. Allergenic compounds found on the plant surface can cause permanent nerve damage, making the harvest of castor beans a human health risk. India, Brazil, and China are the major crop producers and the workers suffer harmful side effects from working with these plants. These health issues, in addition to concerns about the toxic byproduct (ricin) from castor oil production, have encouraged the quest for alternative sources for hydroxy fatty acids. Alternatively, some researchers are trying to genetically modify the castor plant to prevent the synthesis of ricin.
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In the food industry, castor oil (food grade) is used in food additives, flavorings, candy (e.g., chocolate), as a mold inhibitor, and in packaging. Polyoxyethylated castor oil (e.g., Cremophor EL) is also used in the foodstuff industries.
The United States Food and Drug Administration (FDA) has categorized castor oil as "generally recognized as safe and effective" (GRASE) for over-the-counter use as a laxative, with its major site of action the small intestine. However, although it may be used for constipation, it is not a preferred treatment. Undecylenic acid, a castor oil derivative, is also FDA-approved for over-the-counter use on skin disorders or skin problems.
Castor oil penetrates deep into the skin thanks to its molecular weight, which is low enough to penetrate into the stratum corneum. Castor Isostearate Succinate is a polymeric mixture of esters with Isostearic Acid and Succinic Acid used for skin conditioning, such as in shampoo, lipstick and lip balm.
Therapeutically, modern drugs are rarely given in a pure chemical state, so most active ingredients are combined with excipients or additives. Castor oil, or a castor oil derivative such as Cremophor EL (polyethoxylated castor oil, a nonionic surfactant), is added to many modern drugs, including:
The use of cold pressed castor oil in folk medicine predates government medical regulations. Cold pressed castor oil is tasteless and odorless when pure. Uses include skin problems, burns, sunburns, skin disorders, skin cuts, and abrasions. Castor oil has also been used to draw out styes in the eye by pouring a small amount into the eye and allowing it to circulate around the inside of the eyelid. Note that most bottles of castor oil indicate the oil is to be kept away from the eyes. The oil is also used as a rub or pack for various ailments, including abdominal complaints, headaches, muscle pains, inflammatory conditions, skin eruptions, lesions, and sinusitis. A castor oil pack is made by soaking a piece of flannel in castor oil, then putting it on the area of complaint and placing a heat source, such as a hot water bottle, on top of it. This remedy was often suggested by the American psychic Edgar Cayce, given in many healing readings in the early mid-1900s. Castor oil has also been noted for its acne-healing abilities.
Castor oil has been used to induce childbirth in pregnant women, though it is not always effective in application. Castor oil, when ingested, triggers cramping in the bowel (making it an effective laxative). Thus, it is intended that such cramping extend to the uterus. In an overdue pregnancy in which the mother's cervix is already effacing and partially dilated, this cramping can lead to labor contractions. The irregular, painful contractions of castor-oil-induced labor can be stressful on the mother and fetus. It also leaves the laboring woman quite dehydrated as a result of the vomiting and diarrhea which result when the recommended dose of castor oil for labor induction is taken—2 oz, or about 8 tbsp. This leaves her without access to the energy she could otherwise derive from food or drink throughout her labor process. Using castor oil for induction is not recommended without consulting a medical practitioner and is not recommended in a complex pregnancy.. In south Egypt, women use a dose of full large spoon of castor oil to prevent pregnancy for one year. It has also been claimed that castor promotes eyelash growth, however there's no supporting scientific data. 
Castor oil has numerous applications in transportation, cosmetics and pharmaceutical, and manufacturing industries, for example: adhesives, brake fluids, caulks, dyes, electrical liquid dielectrics, humectants, hydraulic fluids, inks, lacquers, leather treatments, lubricating greases, machining oils, paints, pigments, polyurethane adhesives, refrigeration lubricants, rubbers, sealants, textiles, washing powders, and waxes.
Vegetable oils, due to their good lubricity and biodegradability are attractive alternatives to petroleum-derived lubricants, but oxidative stability and low temperature performance limit their widespread use. Castor oil has better low temperature viscosity properties and high temperature lubrication than most vegetable oils, making it useful as a lubricant in jet, diesel, and race-car engines. However, castor oil tends to form gums in a short time, and its use is therefore restricted to engines that are regularly rebuilt, such as race engines. Biodegradability results in decreased persistence in the environment (relative to petroleum-based lubricants) in case of an accidental release. The lubricants company Castrol took its name from castor oil.
Castor oil is the raw material for the production of a number of chemicals, notably sebacic acid, undecylenic acid, nylon-11. A review listing numerous chemicals derived from castor oil is available.
Castor oil was the preferred lubricant for the early aviation powerplant design known as the rotary engine, such as the Gnome engines used in pre-World War I "pioneer aircraft", after that engine's widespread adoption for aviation in Europe in 1909, and was used almost universally by the rotary engines in World War I Allied aircraft.
The methanol-fuelled glow plug engines used for aeromodelling purposes, since their adoption in the model airplane hobby in 1948, have used castor oil as a dependable lubricant that is highly resistant to degradation when the engine has its fuel-air mixture "leaned out" for maximum engine speed. The aforementioned gummy residue problem can still be troublesome for aeromodelling powerplants lubricated with castor oil, however, usually resulting in eventual ball bearing replacement when the residue builds up too much within the engine's bearing races.
Castor biofuel farming started in 2008 in Ethiopia. Families in the Waletia and Goma Gofa regions of Ethiopia began by seeding castor beans for use in biodiesel. The initiative is run by energy company Global Energy Ethiopia, who are also conducting a research and development programme to create new varieties of castor with better yields. (Sub-Saharan Africa gateway, Science and Development Network website, 2008)
In Fascist Italy under the regime of Benito Mussolini, castor oil was one of the tools of the blackshirts. Political dissidents were force-fed large quantities of castor oil by Fascist paramilitary groups. This technique was said to have been originated by Gabriele D'Annunzio. Victims of this treatment rarely died, though often had to bear the humiliation of the laxative effects resulting from excessive consumption of the oil.
It is said that Mussolini's power was backed by "the bludgeon and castor oil". In lesser quantities, castor oil was also used as an instrument of intimidation, for example to discourage civilians or soldiers who would call in sick either in the factory or in the military. Since its healing properties were widely exaggerated, abuse could be easily masked under pretense of a doctor's prescription. It took decades after Mussolini's death before the myth of castor oil as a panacea for a wide range of diseases and medical conditions was totally demystified, as it was also widely administered to pregnant women, elderly or mentally-ill patients in hospitals in the false belief that it had no negative side effects.
Today the Italian terms manganello and olio di ricino, even used separately, still carry strong political connotations (expecially the latter). These words are still used to satirize patronizing politicians, or the authors of disliked legislation. They should be used with caution in common conversation. The terms Usare l'olio di ricino, ("to use castor oil") and usare il manganello ("use the bludgeon") mean "to coerce or abuse," and can be misunderstood in the absence of proper context.
CASTOR OIL, the fixed oil obtained from the seeds of the castor oil plant or Palma Christi, Ricinus communis, belonging to the natural order Euphorbiaceae. The botanical name is from Lat. ricinus, a tick, from the form and markings of the seed. The plant is a native of tropical Africa, but it has been introduced, and is now cultivated in most tropical and in the warmer temperate countries. In size it varies from a shrubby plant to a tree of from 30 to 40 ft. in height according to the climate in which it grows, being arborescent in tropical latitudes. On account of its very large beautiful palmate-peltate leaves, which sometimes measure as much as 2 ft. in diameter, it is cultivated as an ornamental plant. In the south of England, with the habit of an annual, it ripens its seeds in favourable seasons; and it has been known to come to maturity as far north as Christiania in Norway. Plants are readily grown from seed, which should be sown singly in small pots and placed in heat early in March. The young plants are kept under glass till early in June when they are hardened and put out. The fruit consists of a three-celled capsule, covered externally with soft yielding prickles, and each cell develops a single seed. The seeds of the different cultivated varieties, of which there are a great number, differ much in size and in external markings; but average seeds are of an oval laterally compressed form, with their longest diameter about four lines. They have a shining, marble-grey and brown, thick, leathery outer coat, within which is a thin dark-coloured brittle coat. A large distinct leafy embryo lies in the middle of a dense, oily tissue (endosperm). The seeds contain a toxic substance, which makes them actively poisonous; so much so that three have been known to kill an adult.
The oil is obtained from the seeds by two principal methods - expression and decoction - the latter process being largely used in India, where the oil, on account of its cheapness and abundance is extensively employed for illuminating as well as for other domestic and medicinal purposes. The oil exported from Calcutta to Europe is prepared by shelling and crushing the seeds between rollers. The crushed mass is then placed in hempen cloths and pressed in a screw or hydraulic press. The oil which exudes is mixed with water and heated till the water boils, and the mucilaginous matter in the oil separates as a scum. It is next strained, then bleached in the sunlight, and stored for exportation. A considerable quantity of castor oil of an excellent quality is also made in Italy; and in California the manufacture is conducted on an extensive scale. The following is an outline of the process adopted in a Californian factory. 'The seeds are submitted to a dry heat in a furnace for an hour or thereby, by which they are softened and prepared to part easily with their oil. They are then pressed in a large powerful screw-press, and the oily matter which flows out is caught, mixed with an equal proportion of water, and boiled to purify it from mucilaginous and albuminous matter. After boiling about an hour, it is allowed to cool, the water is drawn off, and the oil is transferred to zinc tanks or clarifiers capable of holding from 60 to loo gallons. In these it stands about eight hours, bleaching in the sun, after which it is ready for storing. By this method loo lb of good seeds yield about 5 gallons of pure oil.
Castor oil is a viscid liquid, almost colourless when pure, possessing only a slight odour, and a mild yet highly nauseous and disagreeable taste. Its specific gravity is 96, a little less than that of water, and it dissolves freely in alcohol, ether and glacial acetic acid. It contains palmitic and several other fatty acids, among which there is one - ricinoleic acid - peculiar to itself. This occurs in combination with glycerin, constituting the greater part of the bulk of the oil.
The active principle to which the oil owes its purgative properties has not been isolated. It is, indeed, probable that it is formed in the intestine, as a result of some decomposition as yet unknown. The dose is from a drachm to an ounce. The pharmacopoeial mixture is best avoided, being almost uniquely nauseous. By far the best way to administer the oil is in capsules. It acts in about five hours, affecting the entire length of the bowel, but not increasing the flow of bile except in very large doses. The mode of its action is unknown. The oil will purge when rubbed into the skin or injected per rectum. It is an invaluable drug in temporary constipation and whenever a mild action is essential, as in pregnancy. It is extremely useful for children and the aged, but must not be employed in cases of chronic constipation, which it only aggravates, whilst relieving the symptoms.