Recently, we’ve been answering questions from our clients regarding the safety of using lavender and tea tree essential oils with young boys. With respect and understanding about your concerns regarding the potential phytoestrogenic effects of these oils, I would like to clear the air by presenting our stance on the debate.


This concern was raised over the findings of a 2007 study which proposed that lavender and tea tree oils may have been responsible for causing abnormal breast tissue growth in young males, due to what was suspected as estrogenic (estrogen-like) and endocrine-disrupting properties in these oils.

The study looked at the cases of 3 young boys in Colorado who showed signs of gynecomastia (abnormal breast tissue growth), and whose seemingly only common thread was the use of commercial products containing lavender and tea tree oils (lavender-scented soap and skin lotions, or shampoos or styling products). Subsequently, after stopping the use of the products in question, their breast tissue growth also ceased. As a result, these oils were put into question as the direct cause of the issue. The study tested the oils, and concluded that they displayed weak estrogenic qualities.

Questions & Concerns With The Study

  • Is it possible that other chemicals found in some personal care products may contribute to or, in some cases, be responsible for the potential side effects?  No investigation was made as to whether the boys had also been exposed to other external factors that are known endocrine disruptors, such as phthalates, parabens, BPA exposure, etc, or local environmental factors such as dioxins and pesticides, despite all cases occurring in Colorado. Both pesticides and phthalates have been found in non-organic essential oils, and both phthalates and parabens are commonly found in cosmetic products.
  • The products used on the boys were not named, thus all of the ingredients were not tested as possible causes, and the products cannot be tested by other parties to corroborate the results. Subsequently, there have been no peer study reviews.
  • Plastic lab-ware used in the study may have contained phthalates, which would have had an effect on the content evaluation of the samples. Essential oils are known to leach phthalates (if present) from the plastics in which they are stored.
  • The amount of essential oils absorbed by the skin is unknown. In the case of wash-off products, the contact with the oils is of such short duration that absorption is negligible.
  • In-vitro tests were done on cancer cells, which are already compromised and multiply faster than normal cells, increasing the likelihood of reaching a false positive.
  • The study has only tested isolates of tea tree and lavender oils, a.k.a linalool. In nature, a whole essential oil has about 500 components which impart a balancing effect, and as such, the oil does not present itself as an isolate. The majority of concerns about aroma chemicals are based on mass-market produced vs. whole essential oils.
  • Finally, common sense indicates that we would certainly see many more cases of gynecomastia in the immeasurable number of infants and children that have been exposed to these oils since their introduction. As the study only observed 3 boys in the same geographical area, the assumption that no other factors may have been contributing to the condition is short-sighted and unrealistic.

The Follow-Up

In response to this study, a subsequent test was performed which showed the opposite results to be true. This study specifically focused on the application of lavender essential oil to the uterus of estrogen-deprived female lab rats over the course of 3 days. According to those who conducted the test, it was applied to the organ at 4% and 20% concentration – 6000 and 30,000 times greater (respectively) than normal skin exposure to multiple cosmetic products. The study concluded there was no estrogenic activity in the rats following the application.

In further support of the safety of lavender and tea tree oils, Robert Tisserand, author of  Essential Oil Safety, has written a formal rebuttal here  He asserts, “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”.

It’s my hope that this helps lay out the study in a clear manner. Please note, I am a herbalist, and not an aromatherapist or scientist. Given the above, however, my conclusion is to feel safe using these beautiful and invaluable therapeutic oils in our products.

How We Use Essential Oils in Our Products

Matter Company will continue to use only use whole, pure essential oils in our formulas, with a <1% essential oil ratio, which is further broken down in our signature combination blends. These essential oils add to the therapeutic value, aroma-therapeutic, and scent story of each specific formula.When creating an essential oil formula, we consult with experts in the field, and have worked with renowned aromatherapists Anne Roebuck, (formally of Aveda), Tracy Pepe (Knows Know Design), and Bonita Barth (Essential Botanicals). The main basis of our formulas is rooted in Herbalism, and we use only whole herbs, which are gently infused for up to 24 hours in small batches. These whole herbs have a therapeutic value, and offer a gentle, holistic effect on the skin.

Our clients’ concerns are taken with the utmost attention, and the positive reviews we receive on our products is testament that we, along with our clients, are making safe, informed choices.

If you have further concerns, or know of other studies done on this subject, please let us know.  We welcome your feedback.