Essential oil 281028 226163805 2008-07-17T02:56:26Z Montco 882433 -sfbsc linkspam An '''essential oil''' is any concentrated, [[hydrophobic]] [[liquid]] containing volatile [[aroma compound]]s from [[plant]]s, which are called aromatic herbs or aromatic plants. They are also known as '''volatile''' or '''ethereal''' oils, or simply as the "oil of" the plant material from which they were extracted, such as ''oil of clove''. An oil is "essential" in the sense that it carries a distinctive scent, or essence, of the plant. Essential oils do not as a group need to have any specific chemical properties in common, beyond conveying characteristic fragrances. They are not to be confused with [[essential fatty acid]]s. Essential oils are generally extracted by [[distill]]ation. Other processes include expression, or [[solvent extraction]]. They are used in [[perfumes]], [[cosmetics]] and bath products, for [[flavoring]] food and drink, and for scenting [[incense]] and household [[:Category:Cleaning products|cleaning products]]. Various essential oils have been used medicinally at different periods in history. [[Medicinal properties|Medical applications]] proposed by those who sell medicinal oils range from skin treatments to remedies for cancer, and are often based on historical use of these oils for these purposes. Such claims are now subject to regulation in most countries, and have grown correspondingly more vague, to stay within these regulations. Interest in essential oils has revived in recent decades, with the popularity of [[aromatherapy]], a branch of [[alternative medicine]] which claims that the specific aromas carried by essential oils have curative effects. Oils are volatilized or diluted in a carrier oil and used in massage, or burned as incense, for example. == Production == {{main|Extraction (fragrance)}} ===Distillation=== {{see also|distillation}} Today, most common essential oils, such as lavender, peppermint, and eucalyptus, are distilled. Raw plant material, consisting of the [[flower]]s, [[leaf|leaves]], [[wood]], [[bark]], [[root]]s, [[seed]]s, or [[peel (fruit)|peel]], is put into an [[alembic]] (distillation apparatus) over [[water]]. As the water is heated the steam passes through the plant material, vaporizing the volatile compounds. The vapors flow through a coil where they condense back to liquid, which is then collected in the receiving vessel. Most oils are distilled in a single process. One exception is Ylang-ylang (''[[Cananga odorata]]''), which takes 22 hours to complete through a [[Fractional distillation| fractional distillation]]. The recondensed water is referred to as a hydrosol, hydrolat, [[herbal distillate]] or plant water essence, which may be sold as another fragrant product. Popular hydrosols are [[rose water]], [[lavender water]], [[lemon balm]], [[clary sage]] and [[orange blossom water]]. The use of herbal distillates in [[cosmetics]] is increasing. Some plant hydrosols have unpleasant smells and are therefore not sold. ===Expression=== Most citrus peel oils are expressed mechanically, or ''[[cold-pressed]]''. Due to the large quantities of oil in citrus peel and the relatively low cost to grow and harvest the raw materials, citrus-fruit oils are cheaper than most other essential oils. Lemon or sweet orange oils that are obtained as [[by-product]]s of the citrus industry are even cheaper. Prior to the discovery of [[distillation]], essential oils were extracted by pressing. ===Solvent extraction=== Most flowers contain too little volatile oil to undergo expression and their chemical components are too delicate and easily denatured by the high heat used in steam distillation. Instead, a [[solvent]] such as [[hexane]] or [[supercritical carbon dioxide]] is used to extract the oils. Extracts from hexane and other hydrophobic solvent are called ''[[Concrete (perfumery)|concrete]]s'', which is a mixture of essential oil, waxes, resins, and other [[lipophilic]] (oil soluble) plant material. Although highly fragrant, concretes contain large quantities of non-fragrant waxes and resins. As such another solvent, often [[ethanol|ethyl alcohol]], which only dissolves the fragrant low-molecular weight compounds, is used to extract the fragrant oil from the concrete. The alcohol is removed by a second distillation, leaving behind the ''[[Absolute (substance)|absolute]]''. Supercritical carbon dioxide is used as a solvent in supercritical fluid extraction. This method has many benefits, including avoiding [[petrochemical]] residues in the product. It does not yield an absolute directly. The supercritical carbon dioxide will extract both the waxes and the essential oils that make up the concrete. Subsequent processing with liquid carbon dioxide, achieved in the same extractor by merely lowering the extraction temperature, will separate the waxes from the essential oils. This lower temperature process prevents the decomposition and denaturing of compounds and provides for a superior product. When the extraction is complete, the pressure is reduced to ambient and the carbon dioxide reverts back to a gas, leaving no residue. Although supercritical carbon dioxide is also used for making [[decaffeinated]] [[coffee]], the actual process is different. ===Production quantities=== Estimates of total production of essential oils are difficult to obtain. One estimate, compiled from data in 1989, 1990 and 1994 from various sources gives the following total production, in tonnes, of essential oils for which more than 1,000 tonnes were produced.<ref>{{cite web | url=http://isotc.iso.org/livelink/livelink/971087/ISO_TC_054__Essential_oils_.pdf | title=ISO TC 54 Business Plan &mdash; Essential oils | accessdate=2006-09-14 }} It is unclear from the source what period of time the quoted figures include.</ref> :{| class="wikitable" ! Oil !! Tonnes |- | [[Sweet orange]] || align="right" | 12,000 |- | ''[[Mentha arvensis]]'' || align="right" | 4,800 |- | [[Peppermint]] || align="right" | 3,200 |- | [[Cedar]]wood || align="right" | 2,600 |- | [[Lemon]] || align="right" | 2,300 |- | ''[[Eucalyptus globulus]]'' || align="right" | 2,070 |- | ''[[Litsea cubeba]]'' || align="right" | 2,000 |- | [[Clove]] (leaf) || align="right" | 2,000 |- | [[Spearmint]] || align="right" | 1,300 |} ==Essential oil use in aromatherapy== {{main|Aromatherapy}} Aromatherapy is a form of [[alternative medicine]], in which healing effects are ascribed to the aromatic compounds in essential oils and other plant extracts. Many common essential oils have medicinal properties that have been applied in [[folk medicine]] since ancient times and are still widely used today. For example, many essential oils have [[antiseptic]] properties.<ref>{{cite journal | url=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&rendertype=abstract&artid=1693916 | title=In vitro antibacterial activity of some plant essential oils | author=Seenivasan Prabuseenivasan, Manickkam Jayakumar, and Savarimuthu Ignacimuthu | journal=BMC Complement Altern Med. | date=[[November 30]] [[2006]] | volume=6 | issue=39 | doi=10.1186/1472-6882-6-39 | accessdate=2006-12-22 | pages=39 | pmid=17134518 }}</ref>. Many are also claimed to have an uplifting effect on the mind. The claims are supported in some studies<ref>{{cite journal | url=http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=16780969&query_hl=8&itool=pubmed_docsum | title=Lemon oil vapor causes an anti-stress effect via modulating the 5-HT and DA activities in mice | author=Komiya M, Takeuchi T, Harada E | journal=Behav Brain Res | date=[[September 25]] [[2006]] | volume=172 | issue=2 | pages=240–9 | accessdate=2006-12-24 | pmid=16780969 | doi=10.1016/j.bbr.2006.05.006 }}</ref><ref>{{cite journal | url=http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=16095639&query_hl=8&itool=pubmed_docsum | title=Ambient odors of orange and lavender reduce anxiety and improve mood in a dental office | author=Hiroko Kuriyama, Satoko Watanabe, Takaaki Nakaya, Ichiro Shigemori, Masakazu Kita, Noriko Yoshida, Daiki Masaki, Toshiaki Tadai, Kotaro Ozasa, Kenji Fukui, and Jiro Imanishi | journal=Physiol Behav | date=[[September 15]] [[2005]] | volume=86 | issue=1-2 | pages=92–5 | pmid=16095639 | doi=10.1016/j.physbeh.2005.06.031 | unused_data=|accessdate-2006-12-24 }}</ref> and unconfirmed in others.<ref>{{cite journal | url=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&rendertype=abstract&artid=1142199 | title=Immunological and Psychological Benefits of Aromatherapy Massage | journal=Evid Based Complement Alternat Med | author=Lehrner J, Marwinski G, Lehr S, Johren P, Deecke L | volume=2 | issue=2 | date=June [[2005]] | accessdate=2006-12-24 | doi=10.1093/ecam/neh087 | pages=179 | pmid=15937558 }}</ref> == Dilution == Essential oils are usually [[lipophilic]] (literally: ''"oil-loving"'') compounds that usually are not [[miscible]] with water. Instead, they can be diluted in [[solvent]]s like pure [[ethanol]] (''alcohol''), [[polyethylene glycol]], or [[oil]]s. == Raw Materials ==<!-- This section is linked from [[Vegetable fats and oils]] --> {{main|List of essential oils}} Essential oils are derived from various sections of plants. Some plants, like the [[bitter orange]], are sources of several types of essential oil. :{| class="wikitable" | | valign="top" | '''<big>[[Berry|Berries]]</big>''' * [[Allspice]] * [[Juniper]] '''<big>[[Seed]]s</big>''' * [[Almond]] * [[Anise]] * [[Celery]] * [[Cumin]] * [[Nutmeg oil]] '''<big>[[Bark]]</big>''' * [[Cassia]] * [[Cinnamon]] * [[Sassafras]] '''<big>[[Wood]]</big>''' * [[Camphor]] * [[Cedar]] * [[Rosewood]] * [[Sandalwood]] * [[Agarwood]] '''<big>[[Rhizome]]</big>''' * [[Galangal]] * [[Ginger]] | valign="top" | '''<big>[[Leaf|Leaves]]</big>''' * [[Basil]] * [[Bay leaf]] * [[Cinnamon]] * [[Common sage]] * [[Eucalyptus]] * [[Lemon grass]] * [[Melaleuca]] * [[Oregano]] * [[Patchouli]] * [[Peppermint]] * [[Pine]] * [[Rosemary]] * [[Spearmint]] * [[Tea tree]] * [[Thyme]] * [[Wintergreen]] '''<big>[[Resin]]</big>''' * [[Frankincense]] * [[Myrrh]] | valign="top" | '''<big>[[Flower]]s</big>''' * [[Chamomile]] * [[Clary sage]] * [[Clove]] * [[Geranium]] * [[Hyssop]] * [[Jasmine]] * [[Lavender]] * [[Leptospermum scoparium|Manuka]] * [[Marjoram]] * [[Orange (fruit)|Orange]] * [[Rose]] * [[Ylang-ylang]] '''<big>[[Peel (fruit)|Peel]]</big>''' * [[Bergamot orange|Bergamot]] * [[Grapefruit]] * [[Lemon]] * [[Lime (fruit)|Lime]] * [[Orange (fruit)|Orange]] * [[Tangerine]] '''<big>[[Root]]</big>''' * [[Valerian (herb)|Valerian]] |} === Rose oil === {{main|Rose oil}} The most well-known essential oil is probably [[rose oil]], produced from the petals of ''[[Rosa damascena]]'' and ''[[Rosa centifolia]]''. Steam-distilled rose oil is known as "rose otto" while the solvent extracted product is known as "rose absolute". == Dangers == <!-- please consider updating the aromatherapy article's section on safety/danger when you update this. --> Because of their concentrated nature, essential oils generally should not be applied directly to the skin in their undiluted or "neat" form. Some can cause severe irritation, or provoke an allergic reaction. Instead, essential oils should be blended with a vegetable-based "carrier" oil (a.k.a., a base, or "fixed" oil) before being applied. Common carrier oils include olive, almond, hazelnut and grapeseed. Common ratio of essential oil disbursed in a carrier oil is 0.5&ndash;3% (most under 10%), and depends on its intended purpose. Some essential oils, including many of the [[citrus]] peel oils, are photosensitizers (i.e., increasing the skin's vulnerability to sunlight, making it more likely to burn). Lavender oil, though generally considered the mildest essential oil, is [[cytotoxic]] to human skin cells<ref>"Cytotoxicity of lavender oil and its major components to human skin cells" Prashar A, Locke IC, Evans CS</ref>. Industrial users of essential oils should consult the [[material safety data sheet]]s (MSDS) to determine the hazards and handling requirements of particular oils. === Gynaecomastia === Some essential oils, particularly [[lavender]] and [[tea tree oil]], have been implicated in causing [[gynaecomastia]], an abnormal breast tissue growth, in prepubescent boys. <ref>{{cite journal |title=Prepubertal gynecomastia linked to lavender and tea tree oils |doi= 10.1056/NEJMoa064725 |journal=New England Journal of Medicine |volume=356 |issue=5 |pages=479–85 |year=2007 |pmid=17267908 |author=Henley, D. V.}}</ref> A child hormone specialist at the [[University of Cambridge]] claimed "... these oils can mimic [[oestrogen]]s" and "people should be a little bit careful about using these products". <ref>{{cite news | url=http://news.bbc.co.uk/2/hi/health/6318043.stm | publisher=BBC News | date=2007-02-01 | accessdate=2007-09-09 | title=Oils make male breasts develop}}</ref> === Pesticide residues === There is some concern about [[pesticide]] residues in essential oils, particularly those used therapeutically. For this reason, many practitioners of aromatherapy choose to buy [[Organic farming|organically]] produced oils. ===Ingestion=== While some advocate the ingestion of essential oils for therapeutic purposes, this should never be done except under the supervision of a professional who is licensed to prescribe such treatment. Some very common essential oils such as Eucalyptus are extremely toxic internally. [[Pharmacopoeia]] standards for medicinal oils should be heeded. Essential oils should always be kept out of the reach of children. Some oils can be toxic to some domestic animals, [[cat]]s in particular. Owners must ensure that their pets do not come into contact with potentially harmful essential oils.<ref>{{cite journal | url=http://www.vet-task-force.com/Abstract-tea-tree-oil.htm | title=Australian tea tree (Melaleuca alternifolia) Oil Poisoning in three purebred cats | journal=Journal of Veterinary Diagnostic Investigation | author=K. Bischoff, F. Guale | volume=10 | issue=108 | date=1998 | accessdate=2006-10-17 | format={{dead link|date=June 2008}} &ndash; <sup>[http://scholar.google.co.uk/scholar?hl=en&lr=&q=intitle%3AAustralian+tea+tree+%28Melaleuca+alternifolia%29+Oil+Poisoning+in+three+purebred+cats&as_publication=Journal+of+Veterinary+Diagnostic+Investigation&as_ylo=&as_yhi=&btnG=Search Scholar search]</sup> }}</ref> The internal use of essential oils should be fully avoided during pregnancy without consulting with a licensed professional, as some can be [[abortifacient]]s in dose 0.5&ndash;10 ml. === Smoke === The smoke from burning essential oils may contain potential [[carcinogen]]s, such as [[polycyclic aromatic hydrocarbons]] (PAHs). Essential oils are naturally high in [[volatile organic compound]]s (VOCs). === Flammable Liquid === The [[flash point]] of an essential oil is different for each oil. Many of the common essential oils such as tea tree, lavender, and citrus oils are classed as a [[HAZMAT Class 3 Flammable Liquids|Class 3 Flammable Liquid]] as they have a flash point of 50-60 °C. Care should be taken when shipping essential oils to ensure the correct procedures are followed for transporting dangerous goods. === Toxicology === [[LD50|LD<sub>50</sub>]] of most essential oils or their main components are 0.5-10 g/kg (orally or skin test).{{Fact|date=February 2007}} == Notes and references == <references/> === Additional references === * {{cite book | author=Kurt Schnaubelt | title=Advanced Aromatherapy: The Science of Essential Oil Therapy | publisher=Healing Arts Press | year=1999 | isbn= 0-89281-743-7 }} * {{cite book | author=Wanda Sellar | title=The Directory of Essential Oils | location=Essex | publisher=The C.W. Daniel Company, Ltd | edition=Reprint | year=2001 | isbn= 0-85207-346-1 }} * {{cite book | author=Robert Tisserand | title=Essential Oil Safety: A Guide for Health Care Professionals | publisher=Churchill Livingstone | year=1995 | isbn= 0-443-05260-3 }} == See also == * [[Alternative medicine]] * [[Aromatherapy]] * [[Enfleurage]] * [[Fragrance oil]] * [[List of essential oils]] * [[List of vegetable oils]] * [[Volatility (chemistry)]] [[Category:Essential oils]] [[Category:Oils]] [[ca:Oli essencial]] [[cs:Silice]] [[da:Æterisk olie]] [[de:Ätherisches Öl]] [[es:Aceite esencial]] [[eo:Volatila oleo]] [[fr:Huile essentielle]] [[io:Esencala oleo]] [[id:Minyak atsiri]] [[it:Olio essenziale]] [[he:שמן אתרי]] [[lt:Eterinis aliejus]] [[hu:Illóolaj]] [[nl:Etherische olie]] [[ja:精油]] [[no:Eteriske oljer]] [[pl:Olejek eteryczny]] [[pt:Óleo essencial]] [[ru:Эфирные масла]] [[sk:Éterický olej]] [[sl:Dišavna olja]] [[sr:Етерично уље]] [[fi:Eteerinen öljy]] [[sv:Eterisk olja]] [[th:น้ำมันหอมระเหย]] [[vi:Tinh dầu]] [[uk:Ефірні олії]] [[zh:精油]]