Last week a young lady emailed us with concerns about the safety of tea tree and lavender essential oils. She had heard of a report linking these two oils to estrogen-disrupting effects in boys. I was surprised because these two oils are widely regarded as two of the safest and most well-known oils. So I did a little research and got to the bottom of her concerns.
The report of concern was a 2007 article in the New England Journal of Medicine suggested that tea tree and lavender oils found in personal care products caused three young boys to have enlarged breast tissue. The report also described a laboratory study that showed estrogen disruptor effects of the oils on human cells.
Study results show inconsistencies
As it turns out, all three boys described in the report were using a commercial soap, balm, shampoo or hair gel product containing some amount of tea tree or lavender oil. However, the actual products used by the boys were never identified and the exact essential oil concentrations in the products were not provided.
The laboratory testing did show a weak endocrine disruption effects for both oils. However, the quality, and purity of the tested oils was not mentioned. Contamination of the oils with adulterants or pesticides was not considered or tested.
Here are the problems with this study. First, the suspect personal care products were never identified and therefore the results cannot be confirmed by anyone else. Second, many cosmetic products and personal care products contain phthalates and other ingredients known to be endocrine disruptors and exposure from such products or other environmental sources was not ruled out . Thirdly, phthalates and pesticides (both known endocrine disruptors) have been found in adulterated and/or non-organic essential oils. As I talk about extensively, most all essential oils are not medicinal quality and are commonly adulterated with distillation chemicals, synthetic compounds and impurities.
So the study was poorly conducted and the estrogen effects in question could easily have come from other ingredients in the personal care products or from contaminants in the essential oils (or both) or from their environment.
A more detailed review of the limitations of this study can be found here:
And over 1100 studies and reports on tea tree oil itself (including the above report) can be found on the Australian Tea Tree Industry website here:
The bottom line
The media loves to latch onto studies, especially ones that warn about something being dangerous to us. As I mentioned last week, study results can be misleading and are often open to interpretation. The only way to truly understand what the results of a study mean are to look at the details of how the study was carried out and the implications that has on the results (also consider where the study funding came from as there could be a conflict of interest).
While it’s true that some types of essential oils can have mild estrogen-like effects, the same is true of some commonly used natural products and even foods we eat, including soybeans and yams to name a few. Essential oils of cypress, fennel and coriander are often used specifically for their hormone stimulating or emulating properties, such as for help with hormonal balance, menstrual regulation and PMS symptoms.
As with any natural remedy, know the quality and history of the product or find a professional or expert who can guide you. For essential oils, it’s best to use un-adulterated, medicinal quality brands that have a long history of safe use and to use them according to accepted methods and doses.
To your best health,
Microbiologist and Natural Health Expert
Henley D, Lipson N, Korach K, Bloch C. Prepubertal Gynecomastia Linked to Lavender and Tea Tree Oils. New England Journal of Medicine, Feb. 1, 2007