Tea tree (Melaleuca alternifolia or M. linariifolia) oil is the essential oil obtained by distillation of the leaves of tea tree, a small tree native to the eastern coast of Australia. Tea tree oil is used topically to treat minor wounds and cuts, and to relieve symptoms of the common cold. It is also a popular ingredient in personal care, home care, and cosmetic products.
Adulteration of tea tree oil appears to be fairly widespread. One recent scientific study found that roughly half of 43 commercial samples tested in three analytical laboratories did not have the appropriate chemical composition consistent with authentic samples of Australian tea tree oil.
In some instances, tea tree oil adulteration may be due to confusion regarding the common name: A number of plants are known as “tea tree,” including species in the genus Melaleuca and the closely related genus Leptospermum, plus species in the genera Kunzea and Baeckea from Australia and New Zealand.
However, most of the adulteration of tea tree oil is believed to be for financial gain. Economically motivated adulteration includes dilution with lower-cost byproducts derived from eucalyptus (Eucalyptus globulus and other species of Eucalyptus) oil and other essential oils, or the addition of pure chemical compounds derived from plant material, fermentation, or chemical synthesis.
Stefan Gafner, PhD, chief science officer of the nonprofit American Botanical Council (ABC) and technical director of the Botanical Adulterants Program, explained: “With prices ranging from $30 to $34 per kilogram and an increasing demand, tea tree oil is a prime target for economically motivated adulteration. Materials that are offered at a substantially lower price should be viewed with suspicion.”
The bulletin was authored by Ezra Bejar, PhD, an expert in botanical research in San Diego, California, and peer-reviewed by 19 experts with knowledge of tea tree oil, medicinal plants, analytical chemistry, and related scientific disciplines. The tea tree oil bulletin includes information about the production and market importance of tea tree oil, a list of known adulterants, data on adulteration frequency, and analytical approaches to detect adulterants.
“Tea tree oil has become a highly popular ingredient in numerous consumer health and household products in the past few decades,” said ABC Founder and Executive Director Mark Blumenthal, who is also director of the Botanical Adulterants Program.
“The information we have collected in our tea tree oil Botanical Adulterants Bulletin confirms what many people in the tea tree and essential oil industry have suspected for a long time: that some sellers of ‘tea tree oil’ are either unknowingly or intentionally selling adulterated, fraudulent material incorrectly labeled as ‘tea tree oil,’” Blumenthal continued. “Hopefully, our bulletin will encourage more manufacturers of products containing tea tree oil to perform appropriate testing to ensure that consumers receive authentic tea tree oil in their health and household products.”
Gafner added a note for quality control personnel in industry: “The determination of the exact chemical composition of tea tree oil by gas chromatography analysis, which enables the detection of the more sophisticated types of adulteration, should be considered as a quality control method by any manufacturer that is using tea tree oil in a product.”
The goal of the BABs is to provide summaries on topics regarding botanical identity and adulteration, thus allowing quality control personnel and lab technicians in the herbal medicine, botanical ingredient, dietary supplement, cosmetic, conventional food, and other industries in which botanical ingredients are used, to be aware of adulteration problems that may be widespread and/or imply health and safety concerns.
The tea tree oil bulletin is the 10th publication in the BAB series. As with all publications of the program, the bulletins are freely accessible to all ABC members, registered users of the ABC website, and all members of the public on the program’s website (registration required).