 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. Many are also claimed to have an uplifting effect on the mind. The claims are supported in some studies and unconfirmed in others. See also: Aromatherapy.
Dilution
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.
Raw Materials
Essential oils are derived from various sections of plants. Some, like orange oil, are derived from any of several sections of the plant.- Berries - Allspice, Juniper.
- Seeds - Almond, Anise, Celery, Cumin, Nutmeg oil.
- Bark - Cassia, Cinnamon, Sassafras.
- Wood - Camphor, Cedar, Rosewood, Sandalwood.
- Rhizome - 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 - Chamomile, Clary sage, Clove, Geranium, Hyssop, Jasmine, Lavender, Manuka, Marjoram, Orange, Rose, Ylang-ylang.
- Peel - Bergamot, Grapefruit, Lemon, Lime, Orange, Tangerine.
- Root - Valerian.
See also: List of essential oils.
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
Because of their concentrated nature, EOs 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 carrier oil (also referred to 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% (most less than 10%) and depends on its purpose. Some EO's including many of the citrus peel oils, are photosensitizers, increasing the skin's reaction to sunlight and making it more likely to burn. Lavender oil, though generally considered the mildest essential oil, is cytotoxic to human skin cells.
Industrial users of essential oils should consult the material safety data sheets (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. A child hormone specialist at the University of Cambridge claimed "... these oils can mimic oestrogens" and "people should be a little bit careful about using these products".
Pesticide residues
There is some concern about pesticide residues in EOs, particularly those used therapeutically. For this reason, many practitioners of aromatherapy choose to buy 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 EOs such as Eucalyptus are extremely toxic internally. Pharmacopoeia standards for medicinal oils should be heeded. EOs 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.
Smoke
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). 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.
Toxicology
LD50 of most EO's or their main components are 0.5-10 g/kg (orally or skin test).
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