bigarade citrus aurantium l. nutmeg myristica fragrans houtt. onion allium cepa l. orange, bitter, flowers citrus aurantium l. orange, bitter, peel orange leaf citrus sinensis (l.) osbeck. orange, sweet orange, sweet, flowers orange, sweet, peel origanum origanum spp. palmarosa cymbopogon martini stapf. paprika capsicum annuum l. parsley petroselinum crispum (mill.) mansf. pepper, black piper nigrum l. pepper, white peppermint mentha piperita l. peruvian balsam myroxylon pereirae klotzsch. petitgrain citrus aurantium l. petitgrain lemon citrus limon (l.) burm. f. petitgrain mandarin or tangerine citrus reticulata blanco. pimenta pimenta officinalis lindl. pimenta leaf pipsissewa leaves chimaphila umbellata nutt. pomegranate punica granatum l. prickly ash bark xanthoxylum (or zanthoxylum) americanum mill. or xanthoxylum clava-herculis l. rose absolute rosa alba l., rosa centifolia l., rosa damascena mill., rosa gallica l., and vars. of these spp. rose (otto of roses, attar of roses) rose buds rose flowers rose fruit (hips) rose geranium pelargonium graveolens l'her. rose leaves rosa spp. rosemary rosmarinus officinalis l. saffron crocus sativus l. sage salvia officinalis l. sage, greek salvia triloba l. sage, spanish salvia lavandulaefolia vahl. st. john's bread ceratonia siliqua l. savory, summer satureia hortensis l. savory, winter satureia montana l. schinus molle schinus molle l. sloe berries (blackthorn berries) prunus spinosa l. spearmint mentha spicata l. spike lavender lavandula latifolia vill. tamarind tamarindus indica l. tangerine citrus reticulata blanco. tarragon artemisia dracunculus l. tea thea sinensis l. thyme thymus vulgaris l. and thymus zygis var. gracilis boiss. thyme, white thyme, wild or creeping thymus serpyllum l. triticum (see dog grass) elymus repens tuberose polianthes tuberosa l. turmeric curcuma longa l. vanilla vanilla planifolia andr. or vanilla tahitensis j. w. moore. violet flowers viola odorata l. violet leaves violet leaves absolute wild cherry bark prunus serotina ehrh. ylang-ylang cananga odorata hook. f. and thoms. zedoary bark curcuma zedoaria rosc. as antimicrobials the most commonly used essential oils with antimicrobial action are: β-caryophyllene, eugenol, eugenol acetate, carvacrol, linalool, thymol, geraniol, geranyl acetate, bicyclogermacrene, cinnamaldehyde, geranial, neral, 1,8-cineole, methyl chavicol, methyl cinnamate, methyl eugenol, camphor, α-thujone, viridiflorol, limonene, (z)-linalool oxide, α-pinene, p-cymene, (e)-caryophyllene, γ-terpinene. some essential oils are effective antimicrobials and have been evaluated for food incorporation in vitro. however, actual deployment is rare because much higher concentrations are required in real foods. some or all of this lower effectiveness is due to large differences between culture medium and foods in: chemistry (especially lipid content), viscosity, and duration of inoculation/storage. dilution essential oils are usually lipophilic (literally: "oil-loving") compounds that are immiscible (not miscible) with water. they can be diluted in solvents like pure ethanol and polyethylene glycol. raw materials essential oils are derived from sections of plants. some plants, like the bitter orange, are sources of several types of essential oil. bark cassia cinnamon sassafras berries allspice juniper flowers cannabis chamomile clary sage clove hops hyssop jasmine lavender manuka marjoram orange pelargonium (scented geranium) plumeria rose ylang-ylang leaves basil bay leaf buchu cinnamon common sage eucalyptus guava lemon grass melaleuca oregano rose bergamot patchouli peppermint pine rosemary spearmint tea tree thyme tsuga wintergreen peel bergamot grapefruit lemon lime orange tangerine resin benzoin copaiba frankincense labdanum myrrh rhizome galangal ginger roots valerian seeds anise buchu celery cumin flax nutmeg oil woods agarwood camphor cedar rosewood sandalwood balsam of peru balsam of peru, an essential oil derived from myroxylon plants, is used in food and drink for flavoring, in perfumes and toiletries for fragrance, and in animal care products. however, national and international surveys identified balsam of peru among the "top five" allergens most commonly causing patch test allergic reactions in people referred to dermatology clinics. garlic oil garlic oil is an essential oil derived from garlic. eucalyptus oil main article: eucalyptus oil most eucalyptus oil on the market is produced from the leaves of eucalyptus globulus. steam-distilled eucalyptus oil is used throughout asia, africa, latin america and south america as a primary cleaning/disinfecting agent added to soaped mop and countertop cleaning solutions; it also possesses insect and limited vermin control properties. note, however, there are hundreds of species of eucalyptus, and perhaps some dozens are used to various extents as sources of essential oils. not only do the products of different species differ greatly in characteristics and effects, but also the products of the very same tree can vary grossly. lavender oil main article: lavender oil lavender essential oil sold at a market in france lavender oil has long been used in the production of perfume. however, studies have shown it can be estrogenic and antiandrogenic, causing problems for prepubescent boys and pregnant women, in particular. lavender essential oil is also used as an insect repellent. rose oil rose oil is 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". toxicity the potential toxicity of essential oil is related to its level or grade of purity, and to the toxicity of specific chemical components of the oil. many essential oils are designed exclusively for their aroma-therapeutic quality; these essential oils generally should not be applied directly to the skin in their undiluted form. some can cause severe irritation, provoke an allergic reaction and, over time, prove toxic to the liver. if ingested or rubbed into the skin, essential oils can be highly poisonous, causing confusion, choking, loss of muscle coordination, difficulty in breathing, pneumonia, seizures, and possibly severe allergic reactions or coma. some essential oils, including many of the citrus peel oils, are photosensitizers, increasing vulnerability of the skin to sunlight. industrial users of essential oils should consult the safety data sheets to determine the hazards and handling requirements of particular oils. even certain therapeutic-grade oils can pose potential threats to individuals with epilepsy or pregnant women. essential oil use in children can pose a danger when misused because of their thin skin and immature livers. this might cause them to be more susceptible to toxic effects than adults. flammability the flash point of each essential oil is different. many of the common essential oils, such as tea tree, lavender, and citrus oils, are classed as class 3 flammable liquids, as they have a flash point of 50–60 °c. gynecomastia estrogenic and antiandrogenic activity have been reported by in vitro study of tea tree oil and lavender essential oils. two published sets of case reports suggest that lavender oil may be implicated in some cases of gynecomastia, an abnormal breast tissue growth in prepubescent boys. the european commission's scientific committee on consumer safety dismissed the claims against tea tree oil as implausible, but did not comment on lavender oil. in 2018, a bbc report on a study stated that tea tree and lavender oils contain eight substances that when tested in tissue culture experiments, increasing the level of estrogen and decreasing the level of testosterone. some of the substances are found in "at least 65 other essential oils". the study did not include animal or human testing. handling exposure to essential oils may cause contact dermatitis. essential oils can be aggressive toward rubbers and plastics, so care must be taken in choosing the correct handling equipment. glass syringes are often used, but have coarse volumetric graduations. chemistry syringes are ideal, as they resist essential oils, are long enough to enter deep vessels, and have fine graduations, facilitating quality control. unlike traditional pipettes, which have difficulty handling viscous fluids, the chemistry syringe, also known as a positive displacement pipette, has a seal and piston arrangement which slides inside the pipette, wiping the essential oil off the pipette wall. ingestion some essential oils qualify as gras flavoring agents for use in foods, beverages, and confectioneries according to strict good manufacturing practice and flavorist standards. pharmacopoeia standards for medicinal oils should be heeded. some oils can be toxic to some domestic animals, cats in particular. the internal use of essential oils can pose hazards to pregnant women, as some can be abortifacients in dose 0.5–10 ml, and thus should not be used during pregnancy. pesticide residues concern about pesticide residues in essential oils, particularly those used therapeutically, means many practitioners of aromatherapy buy organically produced oils. not only are pesticides present in trace quantities, but also the oils themselves are used in tiny quantities and usually in high dilutions. where there is a concern about pesticide residues in food essential oils, such as mint or orange oils, the proper criterion is not solely whether the material is organically produced, but whether it meets the government standards based on actual analysis of its pesticide content. pregnancy some essential oils may contain impurities and additives that may be harmful to pregnant women. certain essential oils are safe to use during pregnancy, but care must be taken when selecting quality and brand. sensitivity to certain smells may cause pregnant women to have adverse side effects with essential oil use, such as headache, vertigo, and nausea. pregnant women often report an abnormal sensitivity to smells and taste, and essential oils can cause irritation and nausea when ingested. toxicology the following table lists the ld50 or median lethal dose for common oils; this is the dose required to kill half the members of a tested animal population. ld50 is intended as a guideline only, and reported values can vary widely due to differences in tested species and testing conditions. common nameoral ld50dermal ld50notes neem14 g/kg>2 g/kg lemon myrtle2.43 g/kg2.25 g/kg frankincense>5 g/kg>5 g/kgboswellia carterii frankincense>2 g/kg>2 g/kgboswellia sacra indian frankincense>2 g/kg>2 g/kgboswellia serrata ylang-ylang>5 g/kg>5 g/kg cedarwood>5 g/kg>5 g/kg roman chamomile>5 g/kg>5 g/kg white camphor>5 g/kg>5 g/kgcinnamomum camphora, extracted from leaves yellow camphor3.73 g/kg>5 g/kgcinnamomum camphora, extracted from bark hot oil3.80 g/kg>5 g/kgcinnamomum camphora, oil extracted from leaves cassia2.80 g/kg0.32 g/kg standardization of derived products in 2002, iso published iso 4720 in which the botanical names of the relevant plants are standardized. the rest of the standards with regards to this topic can be found in the section of ics 71.100.60 further information: british pharmacopoeia and united states pharmacopoeia history the resins of aromatics and plant extracts were retained to produce traditional medicines and scented preparations, such as perfumes and incense, including frankincense, myrrh, cedarwood, juniper berry and cinnamon in ancient egypt may have contained essential oils. in 1923, when archaeologists opened pharaoh tutankhamun’s tomb, they found 50 alabaster jars of essential oils. essential oils have been used in folk medicine over centuries. the persian physician ibn sina, known as avicenna in europe, was first to derive the fragrance of flowers from distillation, while the earliest recorded mention of the techniques and methods used to produce essential oils may be ibn al-baitar (1188–1248), an arab al-andalusian (muslim spain) physician, pharmacist and chemist. rather than refer to essential oils themselves, modern works typically discuss specific chemical compounds of which the essential oils are composed, such as referring to methyl salicylate rather than "oil of wintergreen". essential oils are used in aromatherapy, a branch of alternative medicine that uses essential oils and other aromatic compounds. oils are volatilized, diluted in a carrier oil and used in massage, diffused in the air by a nebulizer or diffuser, heated over a candle flame, or burned as incense.