Difference between revisions of "Essential oil" - New World Encyclopedia

Latest revision as of 12:06, 5 March 2021

Glass vial containing Sandalwood (Santalum album) Essential Oil

Essential oil is any concentrated, hydrophobic (immiscible with water), typically lipophilic (oil or fat soluble) liquid of plants that contains highly volatile aroma compounds and carries a distinctive scent, flavor, or essence of the plant. This large and diverse class of oils also are referred to as volatile oils or ethereal oils. They usually are named for the plants from which they are extracted, such as oil of clove or peppermint oil. Essential oils do not as a group need to have any specific chemical properties in common, beyond conveying characteristic fragrances.

Essential oils are found in diverse parts of plants, including leaves, seeds, flowers, roots, and bark. They are extracted by a variety of techniques, including distillation, expression, and solvent extraction. Essential oils can be very complex chemically, with some essential oils with more than 200 identified chemical substances (Dupler and Odle 2005).

For the plant, essential oils are thought to be vital for the life of the plant, containing compounds that help to fight parasites and infections; many essential oils have anti-bacterial, anti-fungal, and anti-parasitic properties (Dupler and Odle 2005).

For people, essential oils are used in perfumes, cosmetics, and bath products, for flavoring food and drink, for scenting incense and household cleaning products, and for medicinal purposes. They have a long history, being used by the ancient civilizations of Egypt, Greece, India, and Rome; more than 5,000 years ago, the ancient civilizations of Mesopotamia utilized machines for obtaining essential oils from plants (Dupler and Odle 2005).

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

Distillation

Today, most common essential oils, such as lavender, peppermint, and eucalyptus, are distilled, using water and steam to remove the oils from the fresh or dried plants. Raw plant material, consisting of the flowers, leaves, wood, bark, roots, seeds, or 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.

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, using machines to squeeze the oil from the plant material. 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-products of the citrus industry are even cheaper.

Prior to the discovery of distillation, all 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 concretes, which is a mixture of essential oil, waxes, resins, and other lipophilic (miscible with other fats, oils, and so on) plant material.

Although highly fragrant, concretes contain large quantities of non-fragrant waxes and resins. As such another solvent, often 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.

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

Essential oils are very concentrated. One drop of essential oil is equivalent in concentration of plant essence to roughly thirty cups of herbal tea (Dupler and Odle 2005). Some essential oils produced from rose plants require 4,000 pounds of rose petals to make a pound of essential oil and thus are very expensive; however, only one 1000 pounds of lavender plant material is required to produce a pound of lavender oil (Dupler and Odle 2005).

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 metric ton, of essential oils for which more than 1,000 metric ton were produced (ISO Technical Committees (ISO/TCs 2004).

Oil	Metric tons
Sweet orange	12,000
Mentha arvensis	4,800
Peppermint	3,200
Cedarwood	2,600
Lemon	2,300
Eucalyptus globulus	2,070
Litsea cubeba	2,000
Clove (leaf)	2,000
Spearmint	1,300

Types of essential oils and plant part

Essential oils are derived from various sections of plants. Some plants, like the bitter orange, are sources of several types of essential oil.

Berries Allspice Juniper Seeds Almond Anise Celery Cumin Nutmeg oil Bark Cassia Cinnamon Sassafras Wood Camphor Cedar Rosewood Sandalwood Agarwood Rhizome Galangal Ginger	Leaves Basil Bay leaf Cinnamon Common sage Eucalyptus Lemon grass Melaleuca Oregano Patchouli Peppermint Pine Rosemary Spearmint Tea tree Thyme Wintergreen Resin Frankincense Myrrh	Flowers Cannabis Chamomile Clary sage Clove Geranium Hops Hyssop Jasmine Lavender Manuka Marjoram Orange Rose Ylang-ylang Peel Bergamot Grapefruit Lemon Lime Orange Tangerine Root Valerian

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."

Essential oils are usually lipophilic (literally: "Oil-loving") compounds that usually are not miscible with water. Instead, they can be diluted in solvents like pure ethanol (alcohol), polyethylene glycol, or oils.

Uses

Essential oils have been used for thousands of years. In addition to ancient civilizations in Mesopotamia having machines for obtaining essential oils, they have been found in 3,000-year-old tombs in the pyramids of Egypt, and early Greek physicians, such as Hippocrates mentioned the use of plant essences and oil massages for healing and enhancing mood (Dupler and Odle 2005).

Essential oils are used as perfumes, medicines, food flavoring, and as additives for antiseptic and fragrant purposes. They have been used in such healing systems as aromatherapy, massage therapy, and Ayurvedic medicine. They are used for skin conditions (acne, burns, cuts, athlete's foot, sunburn, and so on), muscle and circulation problems (arthritis, high blood pressure, varicose veins), respiratory problems, infections, allergies, asthma, colds, flu, as a digestive aid, and for anxiety, depression, exhaustion, and so forth (Dupler and Olde 2005). Treatment claims are now subject to regulation in most countries, and have grown correspondingly more vague, to stay within these regulations.

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 (Prabuseenivasan et al. 2006). Many essential oils are also claimed to have an uplifting effect on the mind. The claims are supported in some studies (Komiya et al. 2006; Kuriyama et al. 2005), and unconfirmed in others (Lehrner et al. 2005).

Dangers associated with use

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 (also known as, 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 0.5–3 percent (most under 10 percent), and depends on its intended purpose. Some essential oils, including many of the citrus peel oils, are photosensitizers (that is, 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 (Prashar et al. 2004).

Estrogenic and antiandrogenic activity have been reported by in vitro study of tea tree oil and lavender essential oils. Case reports suggest that the oils may be implicated in some cases of gynecomastia, an abnormal breast tissue growth, in prepubescent boys (Henley et al. 2007.; BBC 2007).

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, cats in particular. Owners must ensure that their pets do not come into contact with potentially harmful essential oils (Bischoff and Buale 1998). The internal use of essential oils should be fully avoided during pregnancy without consulting with a licensed professional, as some can be abortifacients in dose 0.5–10 ml.

The smoke from burning essential oils may contain potential carcinogens, such as polycyclic aromatic hydrocarbons (PAHs). Essential oils are naturally high in volatile organic compounds (VOCs).

References
ISBN links support NWE through referral fees

BBC. 2007. Oils "make male breasts develop." BBC News February 1, 2007.
Bischoff, K., and F. Guale. 1998. Australian tea tree (Melaleuca alternifolia): Oil poisoning in three purebred cats. Journal of Veterinary Diagnostic Investigation 10 (108): 208-210. Retrieved September 27, 2008.
Dupler, D., and T. G. Odle. 2005. Essential oils. In J. L. Longe, The Gale Encyclopedia of Alternative Medicine, Farmington Hills, Mich: Thomson/Gale, ISBN 0787693960.
Henley, D. V., N. Lipson, K. S. Korach, and C. A. Bloch 2007. Prepubertal gynecomastia linked to lavender and tea tree oils. New England Journal of Medicine 356(5): 479–85. PMID 17267908. Retrieved September 27, 2008.
ISO Technical Committees (ISO/TCs). 2004. ISO TC 54 Business Plan: Essential oils. ISO Technical Committees. Retrieved September 27, 2008.
Komiya, M., T. Takeuchi, and E. Harada. 2006. Lemon oil vapor causes an anti-stress effect via modulating the 5-HT and DA activities in mice. Behav Brain Res 172(2): 240–9. PMID 16780969. Retrieved September 27, 2008.
Kuriyama, H., S. Watanabe, T. Nakaya, I. Shigemori, M. Kita, N. Yoshida, D. Masaki, T. Tadai, K. Ozasa, K. Fukui, and J. Imanishi. 2005. Immunological and psychological benefits of aromatherapy massage. Evid Based Complement Alternat Med 2(2): 179–184. PMID 15937558. Retrieved September 27, 2008.
Lehrner, J., G. Marwinski, S. Lehr, P. Johren, and L. Deecke. 2005. Ambient odors of orange and lavender reduce anxiety and improve mood in a dental office. Physiol Behav 86(1-2): 92–5. PMID 16095639. Retrieved September 27, 2008.
Prabuseenivasan, S., M. Jayakumar, and S. Ignacimuthu. 2006. In vitro antibacterial activity of some plant essential oils. BMC Complement Altern Med. 6(39): 39. PMID 17134518.
Prashar, A., I. C. Locke, and C. S. Evans. 2004. Cytotoxicity of lavender oil and its major components to human skin cells. Cell Proliferation 37(3): 221-229. Retrieved September 27, 2008.
Schnaubelt, K. 1999. Advanced Aromatherapy: The Science of Essential Oil Therapy. Healing Arts Press. ISBN 0892817437.
Sellar, W. 2001. The Directory of Essential Oils. Essex: The C.W. Daniel Company. ISBN 0852073461.
Tisserand, R. 1995. Essential Oil Safety: A Guide for Health Care Professionals. Churchill Livingstone. ISBN 0443052603.

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History of "Essential oil"

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@@ Line 1: / Line 1: @@
-[[Image:DSCF9677.JPG|thumb|250px|Oil of cloves, also known as clove oil, is an essential oil from the [[clove]] plant, ''[[Syzygium aromaticum]]''. It can be purchased over the counter at [[pharmacies]].]]
+{{Images OK}}{{Approved}}{{copyedited}}
-'''Essential oil''' is any concentrated, hydrophobic (immiscible with water), typically lipophilic (oil or fat soluble) liquid of plants that contains highly volatile [[aroma compound]]s and carries a distinctive scent, flavor, or essence of the plant. This large and diverse class of oils also are referred to as '''volatile oils''' or '''ethereal oils'''. They usually are named for the plants from which they are extracted, such as oil of clove or peppermint oil.  Essential oils do not as a group need to have any specific chemical properties in common, beyond conveying characteristic fragrances.
-Essential oils are found in diverse parts of plants, including leaves, seeds, flowers, roots, and bark. They are extracted by a variety of techniques, including distillation, expression, and solvent extraction. Essential oils can be very complex chemically, with some essential oils with more than 200 identified chemical substances (Dupler and Odle 2005).
+[[Image:SandalwoodEssOil.png|thumb|250px|Glass vial containing Sandalwood (Santalum album) Essential Oil]]
+'''Essential oil''' is any concentrated, hydrophobic (immiscible with water), typically lipophilic (oil or fat soluble) liquid of plants that contains highly volatile [[aroma compound]]s and carries a distinctive scent, flavor, or essence of the plant. This large and diverse class of oils also are referred to as '''volatile oils''' or '''ethereal oils.''' They usually are named for the plants from which they are extracted, such as oil of clove or peppermint oil. Essential oils do not as a group need to have any specific chemical properties in common, beyond conveying characteristic fragrances.
+Essential oils are found in diverse parts of plants, including [[leaf|leaves]], [[seed]]s, [[flower]]s, [[root]]s, and [[bark]]. They are extracted by a variety of techniques, including distillation, expression, and solvent extraction. Essential oils can be very complex chemically, with some essential oils with more than 200 identified chemical substances (Dupler and Odle 2005).
 For the plant, essential oils are thought to be vital for the life of the plant, containing compounds that help to fight parasites and infections; many essential oils have anti-bacterial, anti-fungal, and anti-parasitic properties (Dupler and Odle 2005).
-For people, essential oils are used in [[perfume]]s, [[cosmetics]] and bath products, for [[flavoring]] food and drink, for scenting [[incense]] and household cleaning products, and for medicinal purposes. They have a long history, being used by the ancient civilizations of [[Egypt]], [[Greece]], [[India]], and [[Rome]]; more than 5,000 years ago, the ancient civilizations of Mesopotamia utilized machines for obtaining essential oils from plants (Dupler and Odle 2005).
+For people, essential oils are used in [[perfume]]s, [[cosmetics]], and bath products, for [[flavoring]] food and drink, for scenting [[incense]] and household cleaning products, and for medicinal purposes. They have a long history, being used by the ancient civilizations of [[Egypt]], [[Greece]], [[India]], and [[Rome]]; more than 5,000 years ago, the ancient civilizations of Mesopotamia utilized machines for obtaining essential oils from plants (Dupler and Odle 2005).
 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 ==
 ===Distillation===
+Today, most common essential oils, such as [[lavender]], [[peppermint]], and [[eucalyptus]], are distilled, using water and steam to remove the oils from the fresh or dried plants. 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.
-Today, most common essential oils, such as [[lavender]], [[peppermint]], and [[eucalyptus]], are distilled, using water and steam to remove the oils from the fresh or dried plants.  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]].
-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]]'', using machines to squeeze the oil from the plant material. 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.
+Most citrus peel oils are expressed mechanically, or ''[[cold-pressed]],'' using machines to squeeze the oil from the plant material. 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]], all 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, [[wax]]es, [[resin]]s, and other [[lipophilic]] (miscible with other fats, oils, etc.) plant material.
+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, [[wax]]es, [[resin]]s, and other [[lipophilic]] (miscible with other fats, oils, and so on) 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.
+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===
-Essential oils are very concentrated. One drop of essential oil is equivalent in concentration of plant essence to roughly thirty cups of herbal tea (Dupler and Odle 2005). Some essential oils produced from rose plants require 4,000 pounds of rose petals to make a pound of essential oil and thus is very expensive; however, only one 1000 pounds of lavender plant material is required to produce a pound of lavender oil (Dupler and Odle 2005).
+Essential oils are very concentrated. One drop of essential oil is equivalent in concentration of plant essence to roughly thirty cups of herbal tea (Dupler and Odle 2005). Some essential oils produced from rose plants require 4,000 pounds of rose petals to make a pound of essential oil and thus are very expensive; however, only one 1000 pounds of [[lavender]] plant material is required to produce a pound of lavender oil (Dupler and Odle 2005).
 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 metric ton, of essential oils for which more than 1,000 metric ton were produced (ISO Technical Committees (ISO/TCs 2004).
@@ Line 60: / Line 61: @@
 == Types of essential oils and plant part ==
 Essential oils are derived from various sections of plants. Some plants, like the [[bitter orange]], are sources of several types of essential oil.
@@ Line 150: / Line 150: @@
 |}
-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".
+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."
+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.
 ==Uses==
-:Add history here
+Essential oils have been used for thousands of years. In addition to ancient civilizations in Mesopotamia having machines for obtaining essential oils, they have been found in 3,000-year-old tombs in the pyramids of Egypt, and early Greek physicians, such as [[Hippocrates]] mentioned the use of plant essences and oil massages for healing and enhancing mood (Dupler and Odle 2005).
-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.
-==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.
-== Dangers ==
-<!-- please consider updating the aromatherapy article's section on safety/danger when you update this. —>
+Essential oils are used as perfumes, medicines, food flavoring, and as additives for antiseptic and fragrant purposes. They have been used in such healing systems as aromatherapy, massage therapy, and Ayurvedic medicine. They are used for skin conditions (acne, burns, cuts, athlete's foot, sunburn, and so on), muscle and circulation problems (arthritis, high blood pressure, varicose veins), respiratory problems, infections, allergies, asthma, colds, [[influenza|flu]], as a digestive aid, and for anxiety, depression, exhaustion, and so forth (Dupler and Olde 2005). Treatment claims are now subject to regulation in most countries, and have grown correspondingly more vague, to stay within these regulations.
-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>.
+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 (Prabuseenivasan et al. 2006). Many essential oils are also claimed to have an uplifting effect on the mind. The claims are supported in some studies (Komiya et al. 2006; Kuriyama et al. 2005), and unconfirmed in others (Lehrner et al. 2005).
-Industrial users of essential oils should consult the [[material safety data sheet]]s (MSDS) to determine the hazards and handling requirements of particular oils.
+===Dangers associated with use===
+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 (also known as, 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 percent (most under 10 percent), and depends on its intended purpose. Some essential oils, including many of the [[citrus]] peel oils, are [[photosensitizers]] (that is, 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 (Prashar et al. 2004).
-=== Gynecomastia ===
+[[Estrogen]]ic and [[antiandrogen]]ic activity have been reported by in vitro study of [[tea tree oil]] and [[lavender]] essential oils. Case reports suggest that the oils may be implicated in some cases of [[gynecomastia]], an abnormal breast tissue growth, in prepubescent boys (Henley et al. 2007.; BBC 2007).
-[[Estrogen]]ic and [[antiandrogen]]ic activity have been reported by ''in vitro'' study of [[tea tree oil]] and [[lavender]] essential oils. Case reports suggest that the oils may be implicated in some cases of [[gynecomastia]], an abnormal breast tissue growth, in prepubescent boys.<ref>{{cite journal
+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 (Bischoff and Buale 1998). 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&nbsp;ml.
- |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><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&nbsp;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}}
 == References ==
+* BBC. 2007. [http://news.bbc.co.uk/2/hi/health/6318043.stm Oils "make male breasts develop."] ''BBC News'' February 1, 2007.
+* Bischoff, K., and F. Guale. 1998. [http://www.jvdi.org/cgi/reprint/10/2/208 Australian tea tree ''(Melaleuca alternifolia)'': Oil poisoning in three purebred cats.] ''Journal of Veterinary Diagnostic Investigation'' 10 (108): 208-210. Retrieved September 27, 2008.
-* Dupler, D., and T. G. Odle. 2005. Essential oils. In J. L. Longe, ''The Gale Encyclopedia of Alternative Medicine,'' Farmington Hills, Mich: Thomson/Gale,  ISBN 0787693960.
+* Dupler, D., and T. G. Odle. 2005. Essential oils. In J. L. Longe, ''The Gale Encyclopedia of Alternative Medicine,'' Farmington Hills, Mich: Thomson/Gale, ISBN 0787693960.
+* Henley, D. V., N. Lipson, K. S. Korach, and C. A. Bloch 2007. [http://content.nejm.org/cgi/content/abstract/356/5/479 Prepubertal gynecomastia linked to lavender and tea tree oils.] ''New England Journal of Medicine'' 356(5): 479–85. PMID 17267908. Retrieved September 27, 2008.
-* ISO Technical Committees (ISO/TCs). 2004. [http://isotc.iso.org/livelink/livelink/fetch/2000/2122/687806/ISO_TC_054__Essential_oils_.pdf?nodeid=971087&vernum=0 ISO TC 54 Business Plan: Essential oils]. ''ISO Technical Committees''. Retrieved September 27, 2008.</ref>
+* ISO Technical Committees (ISO/TCs). 2004. [http://isotc.iso.org/livelink/livelink/fetch/2000/2122/687806/ISO_TC_054__Essential_oils_.pdf?nodeid=971087&vernum=0 ISO TC 54 Business Plan: Essential oils.] ''ISO Technical Committees''. Retrieved September 27, 2008.
+* Komiya, M., T. Takeuchi, and E. Harada. 2006. [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=16780969&query_hl=8&itool=pubmed_docsum Lemon oil vapor causes an anti-stress effect via modulating the 5-HT and DA activities in mice.] ''Behav Brain Res'' 172(2): 240–9. PMID 16780969. Retrieved September 27, 2008.
+* Kuriyama, H., S. Watanabe, T. Nakaya, I. Shigemori, M. Kita, N. Yoshida, D. Masaki, T. Tadai, K. Ozasa, K. Fukui, and J. Imanishi. 2005. [http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&rendertype=abstract&artid=1142199 Immunological and psychological benefits of aromatherapy massage.] ''Evid Based Complement Alternat Med'' 2(2): 179–184. PMID 15937558. Retrieved September 27, 2008.
-* {{cite book
+* Lehrner, J., G. Marwinski, S. Lehr, P. Johren, and L. Deecke. 2005. [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=16095639&query_hl=8&itool=pubmed_docsum Ambient odors of orange and lavender reduce anxiety and improve mood in a dental office.] ''Physiol Behav'' 86(1-2): 92–5. PMID 16095639. Retrieved September 27, 2008.
- | author=Kurt Schnaubelt
+* Prabuseenivasan, S., M. Jayakumar, and S. Ignacimuthu. 2006. [http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&rendertype=abstract&artid=1693916 In vitro antibacterial activity of some plant essential oils.] ''BMC Complement Altern Med.'' 6(39): 39. PMID 17134518.
- | title=Advanced Aromatherapy: The Science of Essential Oil Therapy
+* Prashar, A., I. C. Locke, and C. S. Evans. 2004. [http://www3.interscience.wiley.com/journal/118794300/abstract?CRETRY=1&SRETRY=0 Cytotoxicity of lavender oil and its major components to human skin cells.] ''Cell Proliferation'' 37(3): 221-229. Retrieved September 27, 2008.
- | publisher=Healing Arts Press
+* Schnaubelt, K. 1999. ''Advanced Aromatherapy: The Science of Essential Oil Therapy''. Healing Arts Press. ISBN 0892817437.
- | year=1999
+* Sellar, W. 2001. ''The Directory of Essential Oils''. Essex: The C.W. Daniel Company. ISBN 0852073461.
- | isbn= 0-89281-743-7
+* Tisserand, R. 1995. ''Essential Oil Safety: A Guide for Health Care Professionals''. Churchill Livingstone. ISBN 0443052603.
-}}
-* {{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:Life sciences]]