Botanical name Betula lenta L.
Synonyms Black birch, cherry birch, mahogany birch, southern birch
Description / Colour / Consistency A thin, colorless to pale yellow liquid.
Aromatic Summary/ Strength of Aroma Birch Sweet has a sweet, sharp, camphoraceous scent that is very fresh and similar to Wintergreen (smells like root beer), and offers a strong top note in perfumery.
Blends With Sweeter citruses, herbs and woody oils, and spice oils.
Birch essential oil (Betula lenta) is a rare and hard to produce oil created from the steam distillation of the Bark of the tree. Because of the challenge to sustainably, safely, and frequently harvest, it's difficult to find a quality supplier of this oil. Many companies offer birch only seasonal and in very limited quantities, or it'll be diluted or of weaker potency.
The Birch tree is a graceful tree about 25m high, which has a pyramidal shape while young. It has bright green leaves and a dark reddish-brown aromatic bark, which his broken into plates or patches.
barked birches in particular are cultivated as ornamental trees, largely for their appearance in winter. The Himalayan birch, Betula utilis, especially the variety or subspecies jacquemontii, is among the most widely planted for this purpose. It has been cultivated since the 1870s, and many cultivars are available, including 'Doorenbos', 'Grayswood Ghost' and 'Silver Shadow'; 'Knightshayes' has a slightly weeping habit
Sweet Birch (Betula Lenta) oil is toxic and can cause skin irritations. Pregnant women should avoid birch oil due to its powerful effects that could hurt their unborn child.
Methyl salicylate 90.4%
Ethyl salicylate 5.5%
Linalyl acetate 1.1%
Specific gravity 1.160 - 1.195 20ºC 1.181
Refractive index 1.523 - 1.543 20ºC 1.5353
Optical rotation -1.0º to + 1.0º 20ºC Compile
Assay >99.0 %
Hazards: Drug interaction; inhibits blood clotting; toxicity; high doses may be teratogenic.
Contraindications (all routes) Anticoagulant medication, major surgery, hemophilia, other bleeding disorders. Pregnancy, breastfeeding. Should not be used on or given to children. Should not be given to people with salicylate sensitivity.
Contraindications (oral) Gastroesophageal reflux disease.
Maximum adult daily oral dose 182 mg
Maximum dermal use level 2.5%
Our safety advice Our oral and dermal restrictions are based on a total of 95.9%total salicylate and methyl salicylate limits of 2.5 mg/kg/day and 2.4% . Oral use of methyl salicylate-rich essential oils should be avoided in GERD, and salicylates are contraindicated in children due to the risk of developing Reye’s syndrome. Essential oils with a high methyl salicylate content should be avoided in pregnancy and lactation, and by anyone concurrently taking anticoagulant drugs. Caution is advised in those with hypersensitivity to salicylates, or dermatological conditions where the integrity of the skin is impaired.
Regulatory guidelines An ADI for methyl salicylate was set at 0.5 mg/kg bw by the Joint FAO/WHO Expert Committee on Food Additives in 1967 based on a dog NOAEL of 50 mg/kg and an uncertainty factor of 100. The same ADI, based on a two year rat study in 1963, was adopted by the Council of Europe Committee of Experts on Flavoring Substances. The Health Canada maximum for methyl salicylate is 1% in topical products.
Adverse skin reactions Undiluted sweet birch oil was moderately irritating to rabbits and was irritating to both mice and pigs; tested at 4% on 25 volunteers it was neither irritating nor sensitizing. It is non-phototoxic
Acute toxicity (human) Numerous cases of poisoning have been reported from ingestion of wintergreen oil or methyl salicylate, with a 50–60% mortality rate; 4–8 mL is considered a lethal dose for a child. Methyl salicylate could be 1.5–4.5 times more toxic in humans than in rodents. In the years 1926, 1928 and 1939–1943, 427 deaths occurred in the US from methyl salicylate or wintergreen oil poisoning. Common signs of methyl salicylate poisoning are: CNS excitation; rapid breathing; fever; high blood pressure; convulsions; coma. Death results from respiratory failure after a period of unconsciousness. Methyl salicylate can be absorbed transdermally in sufficient quantities to cause poisoning in humans.
Comments The ethyl salicylate content probably also contributes to the toxicity of the oil. The oil does not pre-exist in the bark, but is formed by the interaction of a glucoside, gaultherin, and an enzyme, betulase. Many ‘sweet birch oils’ are in fact synthetic methyl salicylate. Many liniments, mouthwashes, inhalants and soft drink flavorings contain methyl salicylate. Knowing that the LD50 in rodents is 1.0 g/kg, and assuming that methyl salicylate is five times more toxic in humans, this would give a human LD50 of 200 mg/kg, which is equivalent to 13 g in an adult or 4–8 g in a child.