Do essential oils and their chemical components present health concerns? Whether or not lavender and tea tree contain endocrine or hormone disrupting chemicals (EDCs) remains unresolved as a debate rages between the players in this protracted essential oil drama. This debate has now been pushed far beyond just essential oils to what we eat and what we put in and on our bodies.
It is likely that you and your children are exposed every day to the common chemical components that are discussed in this article and that are now in the crosshairs of a March 2018 US Federal Government study.
In fact, many of us have recently ingested these compounds. The purpose of these articles is to fully examine the available technical information, facts, reports, data, and opinions to form a well-founded conclusion on this important question that affects millions of people daily.
This issue is complex and emotional to many in that it involves deeply held beliefs and agendas, vast sums of money, the US federal government, its labyrinth of agencies (and other governments worldwide), and the cosmetics, pharmaceutical, essential oils, and food and flavor industries.
This issue also affects the millions of people worldwide that rely upon and believe in natural and/or organic forms of remedies, the hundreds (even thousands) of companies that use lavender and tea tree oils in their products, researchers that may or may not be somehow beholden to any the above interests, and the natural compounds (and/or synthetic variants) that have been relied upon by humans for many generations. As with any topic of this complexity, the truth is elusive.
The genesis of this essential oil controversy:
Bigger Breasts, Lavender, and Tea Tree, Oh my!
The infamous 2007 Report.
The controversy regarding the alleged safety of lavender and tea tree oils originated with a study and report published in The New England journal of medicine on February 1, 2007 entitled: Prepubertal Gynecomastia Linked to Lavender and Tea Tree Oils. (“The 2007 Report”)
As detailed below, many professionals opined on and rebutted this report on many grounds. The original authors of the report produced nearly nothing of substance on the issue to respond to the harsh criticism about the study, the report, its methods, and the ultimate conclusions.
(In addition, despite the certainty of the report’s title, the body of the report uses language that is anything but certain, such as: “probably”, “suggest that”, “may contribute to”, “we suspect that”, “the possibility of”, etc.
After exactly 11 years, this debate was resurrected with a vengeance by the presentation of a study on March 19, 2018 at the Endocrine Society’s 100th meeting in Chicago entitled: Steroid Receptor Hormonal Actions of Lavender and Tea Tree Oil Components. (“The 2018 Report”)
The authors of this (in vitro) study claim that: “… our study has identified eight components of [lavender oil] and [tea tree oil] as endocrine disruptor chemicals (EDCs).”
[Note that the 2018 report studied 8 constituent components (of hundreds total) contained in lavender and tea tree essential oils, which are detailed below, not the actual essential oils. It’s also important to note that these 8 compounds are widely used in the cosmetics, pharmaceutical, food, and flavor industries.]
Both of the above reports are referred to as “the 2007 report” and “the 2018 report”, collectively, “the reports”. Part I of this paper addresses the 2007 report; Part II will address the 2018 report.
The stakes in this essential oil controversy have been raised considerably.
Not only has this debate been re-ignited, but now the investigators/authors of the 2018 report have called into question the public health and safety of all essential oils, including very common and widely-used chemical components such as linalool, terpineol, and limonene.
The primary author of the 2018 report, Jeffrey Tyler Ramsey states:
“Lavender oil and tea tree oil pose potential environmental health concerns and should be investigated further.”
Background of Terms, Compounds, and the Players in this drama
The Key Terminology
Essential oils are concentrated hydrophobic (repellent to water) and volatile (they dissipate or evaporate) extracts from plants and botanicals including flowers, leaves, berries, barks, peels, resins, woods, seeds roots, and rhizomes. The word “essential” arises from the fact that the oils contain the essence of the plant/botanical material from which it was extracted, (including the material’s fragrance).
Endocrine disruptors (EDCs, also sometimes called hormone disruptors, endocrine-disrupting compounds/chemicals, and hormonally-active agents) are chemical compounds that can interfere with the human body’s endocrine (hormone) systems. These endocrine-system disruptions can cause a host of problems including cancers, birth defects, developmental disorders, sexual development problems. Any bodily functions controlled by hormones can be impacted by hormone-disrupting chemicals.
Gynecomastia is characterized by enlarged breast tissue and usually results from disrupted estrogen and/or androgen signaling which leads to an increase in or unopposed estrogen action on breast tissue. Prepubertal Gynecomastia is typically rare and is prior to the onset of puberty.
Estrogen is the primary female sex hormone. It is responsible for the development and regulation of the female reproductive system and secondary sex characteristics.
Anti-androgenic or antiandrogens, also known as androgen antagonists or testosterone blockers are compounds or drugs that prevent androgens (like testosterone) from carrying out their effects on the human body. They act by blocking the androgen receptor (AR) and/or inhibiting or suppressing the body’s androgen production. (Antiandrogens are one of three types of “sex-hormone antagonists”, the other two being antiprogestogens and antiestrogens.)
Topical exposure (or application) refers to a substance applied to the body (usually skin) rather than taken internally or injected subcutaneous. Oils, lotions, creams, balms, ointments, etc. are topically applied to the skin.
In vitro comes from Latin and literally means “in glass”. Refers to studies, tests, or experiments typically done in a test tube or other glass vessel (as opposed to on a human or other living animal.)
In vivo comes from Latin and literally means “within the living” and refers to studies, tests, or experiments conducted with a living person or animal.
(Note: It’s critical to understand that an in vitro experiment does not equate with an in vivo experiment.)
Idiopathic means when an underlying cause is not identified.
Phytochemicals are chemical compounds that are produced by plants.
Terpenes are a large class of organic compounds that are produced by many different types of plants. Terpenes are the primary components of essential oils. Terpenes are used extensively in the cosmetics, food, drug, and biotechnology industries.
Lavender and Tea Tree Essential Oils
Lavender is a widely spread genus of flowering plants in the mint family, has been cultivated and used by humans for centuries, and has 47 known species, the most common of which is (Lavandula Angustifolia). Lavender is extensively cultivated as an ornamental, for garden and landscape uses, for culinary purposes, and commercially for the extraction of essential oils. Lavender essential oil is a complex mixture of over 100 phytochemical compounds, the most common of which are linalool, Linalyl acetate, and eucalyptol.
Lavender essential oil reputedly has antiseptic and anti-inflammatory properties and is also used as a bug and mosquito repellent. It has been used in perfumes for centuries and is very widely used in the cosmetics industry as a fragrance ingredient for nearly every type of cosmetic product on the market. Lavender oil has been approved by the US Food and Drug Administration (FDA) as “generally recognized as safe” (GRAS) in the Code of Federal Regulations.
Tea Tree (Melaleuca Alternifolia) is an essential oil extracted from the leaves of the “tea tree” which is native to Southeast Queensland and the Northeast coast of New South Wales Australia. It has a fresh, pleasant camphor-like aroma and ranges in color from clear to pale yellow. It contains nearly 100 different chemical compounds and is used to treat acne, dandruff, lice, insect bites, scabies and as an anti-fungal and anti-bacterial. The commercial tea tree industry developed in the early 1900s. Tea tree is commonly sold in its pure, extracted form and is an ingredient in thousands of commercial products for skin, hair, and face.
Key chemical components of Lavender and Tea Tree Essential Oils
Linalool Is a naturally-occurring monoterpene that is present in high concentrations in over 200 species of flowers, spices, and plants including lavender, orange, rose, coriander, cilantro, basil, bay, hops, and cannabis. Linalool is usually a pale yellow liquid, has an unusually pleasant floral/spicy aroma, and is very widely used as a fragrance ingredient in cosmetics and cleaning products. Most interestingly, it has shown preliminary promise for treatment of Alzheimer’s, cancers, and leukemia.
https://www.ncbi.nlm.nih.gov/pubmed/24858101 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5124981/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4691036/
Limonene Is a stable and mostly clear liquid monoterpene which is a major component in the oils of citrus fruit peels. It is typically extracted from citrus fruits via steam distillation or centrifugal separation. The more common D-isomer (“d-limonene”) smells of oranges, is very common in nature, and is widely used as a fragrance for cosmetics, a dietary supplement, a food flavoring ingredient, in cleaning products and many personal care products such as bath products, and hand cleansers.
Linalyl acetate is a naturally occurring phytochemical found in many flowers and spice plants. It is one of the principal components of the essential oils of bergamot and lavender. Chemically, it is the acetate ester of linalool, and the two often occur in conjunction. It is considered as a perfume and essence compound and imparts a distinct and pleasant flavor and fragrance of lavender to many commercial products.
Eucalyptol has a fresh mint-like smell and a spicy, cooling taste. It comprises up to 90 percent of the essential oil of some species of the generic product Eucalyptus oil hence the common name of the compound. It is also found in camphor laurel, bay leaves, tea tree, sweet basil, wormwood, rosemary, common sage, cannabis sativa and other aromatic plant foliage.
In very low amounts, it can be used internally as a flavoring and medicine ingredient. Because of its pleasant spicy aroma and taste, eucalyptol is used in flavorings, fragrances, and cosmetics. Eucalyptus oil is used as a flavoring at low levels (0.002%) in various products, including baked goods, confectionery, meat products and beverages. It is also used as an additives to cigarettes. It is claimed that it is added to improve the flavor.
4-Terpineol (Terpinen-4-ol) is a monoterpene and is an isomer of Terpineol. It has strong antifungal/antibacterial effects. It is considered to be the primary active chemical in tea tree oil and is also the compound with the highest concentration in nutmeg essential oil. It is used in its pure form in commercially-available products for cleaning eyelashes, eyelids, and the face.
Alpha-Terpineol is a monoterpene alcohol that has been isolated from many sources including lavender, tea tree, cajuput, pine, and petitgrain oils. Terpineol has a pleasant floral aroma similar to lilac and is a common ingredient in flavors, cosmetics, and perfumes. In fact, it’s known as ONE OF THE MOST COMMONLY USED OF ALL PERFUME CHEMICALS. It’s one of the two most abundant aroma constituents of lapsang souchong tea.
Alpha-Terpinene is a monoterpene that’s widely used as a flavoring and fragrance chemical in the personal care, cosmetic, pharmaceutical, and food industries. It has a citrusy, spicy, woody, camphoraceous, and thymol aroma and is present in many different essential oils, but is usually isolated from cardamom and marjoram oils (and from other natural sources). It is one of the components responsible for the antioxidant activity of tea tree oil.
Gamma-Terpinene is a volatile monoterpene and is a major component of essential oils made from citrus fruits and shows strong antioxidant activity. It is also derived from tea tree (Melaleuca alternifolia), and shows antimicrobial properties against various human pathogens. It has been isolated from a variety of plant sources, such like coriander, lemon, cumin, and fragrant celery oils. It is also present in grapes, celery, cinnamon, cloves, cumin seeds, ginger, pepper and tea.
The Federal Government Agencies Responsible for the 2007 and 2018 Reports
These studies and reports were conducted and issued under the National Institutes of Health (NIH) Intramural Research Program (IRP) and the National Institute of Environmental Health Sciences (NIEHS). The NIH IRP states as its prime directive
“One program; many people; infinite possibilities. A premier environment where creative scientists conduct fundamental biomedical research for the betterment of human health—we are the IRP.”
The IRP also claims “… 1,200 principal investigators and more than 4,000 Postdoctoral Fellows … the largest biomedical research institution on earth … more than 50 buildings on NIH campuses … Our 240 bed research hospital …” et cetera.
The NIEHS bio and mission asserts that:
“The NIEHS aims to reduce the burden of human illness and disability by understanding how the environment influences the development and progression of human disease. To have the greatest impact on preventing disease and improving human health, the NIEHS focuses on basic science, disease-oriented research, global environmental health, and multidisciplinary training for researchers.”
The Federal agency above this vast labyrinth of institutes, programs, and agencies is the United States Department of Health and Human Services (HHS). It’s a cabinet level department of the Federal Government with a stated goal of protecting the health of all Americans and providing essential human services. The HHS motto is “Improving the health, safety, and well-being of America.”
The Key Authors of the 2007 and 2018 reports
Dr. Kenneth S. Korach, Ph.D., was an investigator and author of both the 2007 and 2018 reports. He is a senior investigator in the Reproductive & Developmental Biology Laboratory/Receptor Biology Group” of NIEHS.
Jeffrey Tyler Ramsey, B.S., is an Intramural Research Training Award (IRTA) fellow at NIEHS. Ramsey Graduated from Appalachian State University in 2016 and has been with NIEHS for over 2 years.
Ramsey is listed as the lead researcher for the 2018 report, “Steroid Receptor Hormonal Actions of Lavender and Tea Tree Oil Components,” which was presented March 19 at ENDO 2018, the Endocrine Society’s 100th annual meeting in Chicago.
[NOTE: The principal author of the 2018 Study is 2+ years removed from college.]
Rebuttals to the 2007 Study
The primary direct rebuttal to the 2007 study is an in vivo study released on January 28, 2013 entitled: Uterotrophic Assay of Percutaneous Lavender Oil in Immature Female Rats. “The 2013 rebuttal” This report stated:
“However, further research is necessary before any conclusive causal relationship can be identified between the essential oils and gynecomastia. Toward this end, a uterotrophic assay of lavender oil by dermal application to rats was initiated. Dermal application was selected to mimic the exposure of the boys described in the report by Henley et al. This higher level test, conducted in vivo and considered to be the benchmark animal assay for estrogenic effects, is the subject of the present report.” …
In summary, results from the present uterotrophic bio assay in rats show that percutaneous dosages of lavender oil equivalent to greater than 6000 and 30 000 times the human maximal daily exposure of 0.003 mg/kg per day (Table 1) and greater than 5000 to 1 000 000 times the estimated exposure from hair and skin care products that may be used by prepubertal boys(Table 3) did not induce a statistically significant increase in mean uterine weight. It is concluded that at the dosages tested, lavender oil is not an estrogenic agonist. [emphasis added]
Robert Tisserand “is an international speaker, educator and consultant on the science and benefits of essential oils and their safe and effective application … Robert has 40 years of experience in essential oil blending and aromatherapy product development including creating “functional fragrances” for products that combine perfumery principles with the therapeutic, hygienic, and dermatological properties of essential oils. He is familiar with the foundations of oriental medicine, and Western herbal and naturopathic traditions, with their emphasis on cleansing, protecting, strengthening immune function and aiding natural healing processes.” (Mr. Tisserand wrote this article in response to the 2007 report (and after the 2013 rebuttal study)
“Lavender oil is not estrogenic: Lavender oil does not mimic estrogen nor does it enhance the body’s own estrogens. It is therefore not a ‘hormone disruptor’, cannot cause breast growth in young boys (or girls of any age), and is safe to use by anyone at risk for estrogen-dependent cancer. The lack of estrogenic action is the conclusion of a new report, which used a novel form of ‘uterotrophic’ assay…” https://www.sciencedirect.com/science/article/pii/S0890623814000239
Jean Bokelmann M.D. Associate Professor of Family Medicine and Geriatrics, Idaho State University (ISU) Director of Integrative Medical Services, ISU Family Practice Residency Program Medical Director of Endobiogenic Integrative Medical Center (EIMC). Dr. Bokelmann wrote a letter to the authors of the 2007 report (prior to the 2013 rebuttal) and stated: “
… [T]here remains a huge cavern of variables that prevent the conclusion of any legitimate “link” between the in vitro findings and the in vivo observations of some astute health care providers. After centuries of clinical use of these oils in Europe and Australia, it is curious that such findings have not previously been noted and correlated with their use. … The real issue is related to the Evel Knievel-style propulsion across the abyss between in vitro findings and in vivo observations.
The authors provide little data about the actual composition of the products that were being applied topically. Anyone looking at this report critically would be compelled to ask many questions about the putatively offending products: Were they essential oils in their natural form, chemically modified essential oils, or synthetic fragrance materials? What were the other ingredients? Did they contain traces of endocrine-disrupting pesticides? … Until in vivo studies are performed and they result in suggestive and/or conclusive outcomes, it is reckless to claim a “link” between either tea tree oil or lavender oil and gynecomastia…” [emphasis added]
The European Commission Scientific Committee on Consumer Products “SCCP” issued a Report and Opinion on tea tree oil (No. SCCP/1155/08) adopted December 16, 2008) and stated:
An estrogenic potential of Tea Tree Oil was shown in vitro. No in vivo studies are available to elucidate the relevance of this finding for the in vivo situation. [Note: until the 2013 rebuttal report] Since the hormonal active ingredients of Tea Tree Oil were shown not to penetrate the skin, the hypothesized correlation of the finding of 3 cases of gynecomastia to the topical use of Tea Tree Oil is considered implausible. [emphasis added]
Christopher Dean, Chairman of the Australian Tea Tree Oil Industry Technical and Safety Committee issued a scathing demand for a retraction of the 2007 report and concluded:
“In short the authors ignore numerous alternate possibilities and draw an unsound conclusion from non significant and very noisy data. This publication is, to say the least, unscientific. The conclusion stated in the summary is not supported by the cell culture studies. The authors show no curiosity at all about the enormous difficulties in attempting to connect the cell culture studies with the case studies scientifically. It is disappointing to see the New England Journal Of medicine publishing such work uncritically, allowing such material to damage its own reputation and to create unwarranted alarm and commercial damage around the world. A retraction is warranted.” [emphasis added]
The Perfumer & Flavorist issued a “Research Rebuttal: Gynecomastia & Essential Oils dated December 31, 2008 and attacked the 2007 report with a list of conclusions and questions that draw many aspects of the 2007 report and its ultimate conclusions into question.
“Therefore, while I do not refute that the cosmetic products that Henley et al. tested were responsible for the boys’ gynaecomastia, there is absolutely no sound clinical and scientific evidence that can link this to lavender and tea tree essential oils. It is very likely to have been triggered by contaminants or other ingredients that we have just examined.”
There are many other rebuttal and contrary opinions that mostly recite the above rebuttal conclusions. There are also a great number of “news” outlets that have simply parroted the original 2007 study and report without any analysis as to the veracity of those conclusions. Many of these outlets have used the 2007 and 2018 reports as a “clickbait” opportunity to sensationalize the claimed findings.
None of these internet publications has anything to add worth quoting or citing, aside from mild entertainment value. If you’re a glutton for punishment, type this into your search bar: “Will lavender and tea tree make your breasts bigger?” You’ve been warned.
My Conclusions: The 2007 report.
There has been no “Link” established between Prepubertal Gynecomastia, bigger breasts, and Lavender and Tea Tree Oils
- There has been NO “LINK” established by the 2007 study and report between Prepubertal Gynecomastia and Lavender and Tea Tree Essential Oils and any such claim is reckless and irresponsible.
- The wishy-washy and non-committal language [“probably”, “suggest that”, “may contribute to”, “we suspect that”, “the possibility of”, et cetera.] of the 2007 Report completely contradicts the seeming certainty of the report’s title that lavender and tea tree oils are somehow “linked” to prepubertal gynecomastia.
- The 2013 in vivo study eviscerates and completely invalidates the “linked” claims made in the 2007 study and report.
- This alleged “link” has been irresponsibly parroted and perpetuated by many sources even though it has been completely discredited, especially in light of the 2013 in vivo study and report.
- The 2007 Report was sloppy in its testing and is riddled with logical holes and faults under the most forgiving of assessments.
- The 2007 study was uncontrolled and in vitro and wholly fails to make a causal connection between the use of Lavender and Tea tree EOs (contained in several topical products) and the prepubertal gynecomastia exhibited by the 3 boys referenced in the 2007 study and report.
- The 2007 report would probably not withstand the evidentiary hurdles to be admitted in most state and federal courts of law as an expert opinion and report. In the unlikely event that this report was deemed to be admissible and to have some evidentiary value, it would most certainly be torn apart during a cross examination by any reasonably competent counsel.
- The actual cause of the prepubertal gynecomastia in the 3 boys that were the subjects of the 2007 study and report has never been positively identified.
- The tested hormone levels of all 3 boys were NORMAL, but for one that was found to have slightly elevated testosterone, not estrogen.
- Lavender and Tea Tree oil (and their constituent chemical components) are now so ubiquitous in body care, cosmetic, food, and other products that we would literally have an epidemic of prepubertal gynecomastia cases in children if these essential oils were truly causing this particular condition. That has not happened during the many hundreds of years these compounds have been used by humans and also in the 11 years since the 2007 report was made public.
- If Lavender and tea tree oils were endocrine disrupting, large numbers of adults would be exhibiting related health problems. There’s not one documented adult health issue that I could find implicating endocrine disrupting symptoms in adults resulting from lavender and tea tree oils.
There are so many logical, testing, and other flaws with the 2007 study and report that it’s shocking it’s referenced with any sort of authority on this topic.
There is no “link” and this study proved absolutely nothing. The most troubling issue is how much needless fear and misunderstanding that the 2007 report created in light of its significant flaws as a scientific study.
It’s also troubling that it’s still cited as an authority in many sources in light of its obvious flaws, such as this entry in Wikipedia:
Estrogenic and antiandrogenic activity have been reported by in vitro study of tea tree oil and lavender essential oils. Case reports suggest the oils 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 as implausible in 2008. However, in 2018, a study led by J. Tyler Ramsey of the American National Institute of Environmental Health Sciences found that these oils contain eight substances that affect human hormones, increasing the level of oestrogen and decreasing the level of testosterone. Some of the substances are found in "at least 65 other essential oils". [Emphasis added; NOTE “may be”.]
My unanswered questions on this issue are as follows:
- Why the push by the National Institutes of Health (NIH) Intramural Research Program (IRP) and the National Institute of Environmental Health Sciences (NIEHS) to demonize lavender and tea tree essential oils?
- If this is such a critical issue to the health and safety, why produce such a sloppy and shoddy (in vitro) study and report in the first place?
- If this was such a critical issue, why the huge lapse of time between the 2007 Report and the 2018 report?
- Why would federal health and wellness agencies with virtually unlimited funding and resources conduct such shoddy and questionable in vitro studies rather than controlled and comprehensive in vivo studies to obtain an accurate and useful result?
- Why did the 2007 Report single out Lavender and Tea Tree Essential oils, when their constituent components are also contained in many other essential oils and botanicals?
- Why did the 2018 follow up study focus only on 8 constituent components contained in Lavender and Tea Tree (and numerous other essential oils and botanicals) and not pure versions of the essential oils themselves?
- Why the push by the National Institutes of Health (NIH) Intramural Research Program (IRP) and the National Institute of Environmental Health Sciences (NIEHS) to now demonize those 8 components in the 2018 report, which are incredibly widely used in numerous different industries and consumed by millions of people daily? (And which do not appear to cause any human health issues whatsoever, despite millions of people consuming and coming in contact with them daily.)
Part II of this paper will focus on the 2018 report presented on March 19, 2018 at the Endocrine Society’s 100th meeting in Chicago entitled: Steroid Receptor Hormonal Actions of Lavender and Tea Tree Oil Components.
Researching these complex issues and writing this article was driven by my desire to gain a deeper understanding and to know the truth because of its potential impacts on millions of people and on Noble Body.
Disclosure: Noble Body formulations contain natural oils, essential oils, terpenes, and other botanical extracts such as calendula, licorice root, and Arnica. I have also studied, tested, and worked extensively with, CBD, St. John’s Wort, limonene, linalool, terpineol, nerolidol, myrcene, citral, and many other naturally-occurring compounds, aromatic terpenes, and essential oils.
These conclusions and opinions are my own and I have read every source posted in this article (unless otherwise noted) in addition to many other sources of information I could find including podcasts, video presentations, webinars and consults with industry professionals.