Do lavender and tea tree oils cause breast growth and early puberty in children? 

Do lavender and tea tree oils cause breast growth and early puberty in children? 

Through a partnership with the National Association for Holistic Aromatherapy (NAHA), the Australian Tea Tree Industry Association, and the Tisserand Institute, the Franklin Health Research Foundation is leading a 5-phase research project to investigate the proposed link between lavender and tea tree essential oils and endocrine disrupting outcomes, including prepubertal gynecomastia.

While multiple laboratory studies over the last decade have uncovered potential endocrine disrupting effects of essential oils, this proposed link has yet to be either substantiated or rejected through epidemiological studies.

Without an analysis of the effects of these ingredients within the human body, the safety of these two oils in pediatric products (or lack thereof) cannot be confirmed scientifically. These studies will be the first to identify the outcomes of the use of lavender and tea tree essential oils in personal care products for babies and children.

About this Project

This project consists of five separate phases:

  • Background and Review (COMPLETE / PUBLISHED HERE)
  • Measurement Instrument Creation & Validation (COMPLETE / IN PEER REVIEW)
  • Cross-Sectional Study: Phase One (COMPLETE / IN PEER REVIEW)
  • Cross-Sectional Study: Phase Two (IN PROCESS)
  • Case-Control Study (TBD)

The first and most important step was to develop a verified way to measure exposure to these oils in children. This is accomplished by creating and then testing a measurement instrument. In this case, the instrument is a questionnaire which was found to be highly effective at both identifying and quantifying exposure to lavender and tea tree oils over a period of 15 years.

lavender and essential oils

The next step is a cross sectional study to address the call to action raised in the first (2007) publication alleging a proposed link. Thanks to the first study in this project, exposure status can be accurately classified using the measurement approach our team developed. This cross sectional study achieves multiple objectives:

  • It identifies the prevalence of endocrine disruption outcomes among children with confirmed exposure to lavender and/or tea tree essential oils.
  • It compares outcomes among children with confirmed exposure to lavender and/or tea tree oils with those who are confirmed to be free of exposure to these oils, generating odds ratios which can quantify the odds of developing endocrine disorders among exposed/unexposed.
  • It evaluates the dose-dependent potential of exposure to lavender and/or tea tree looking not only at whether or not these oils can cause these outcomes but whether a dose-dependent relationship exists.

This study evaluates children of all genders and endocrine disrupting outcomes beyond prepubertal gynecomastia and precocious puberty.

If either of these two oils are associated with endocrine disrupting activity in children, a case control study will be conducted to find where that association exists. Perhaps it finds that a certain brand of products is linked to the effects. Or perhaps it finds that the effects are only found in a certain region or in children of a certain race. If there is a link, it will be found. If there is not a link, this project provides the first actual scientific evidence that these two essential oils do not cause these outcomes in children.

Frequently Asked Questions

Who are the researchers behind this project?

This project is being conducted by the Franklin Health Research Foundation, which is the 501(c)(3) nonprofit arm of the Franklin Health Research Center, a contract research organization which specializes in clinical research for natural products.

The project is led by Jessie Hawkins, PhD, who brings an extensive background in natural product research to these studies. Dr. Hawkins received her PhD in health research by conducting an RCT on the use of essential oils in children with autism spectrum disorders. She has received a post-doctoral certificate in epidemiology from the highly respected London School of Hygiene and Tropical Medicine and is completing further post-doctoral clinical research/drug development training from Harvard Medical School's esteemed Global Clinical Scholars Research Training program (GCSRT).

The project is supported by Christy Hires, MPH, CHES, who received her clinical trials and research training from the London School of Hygiene and Tropical Medicine, Elizabeth Dunne, MS, RDN, and Lindsey Keenan, RDN, both licensed dietitians who specialize in clinical research on natural and botanical products.

The project has received full IRB authorization for each phase of the study and is registered at

What kind of essential oils are you using?
What chemicals are you testing?
What about all of the other ingredients in skincare?
Are you looking at the possibility of essential oils leaching endocrine disrupting chemicals from plastics?
Doesn't oil quality and adulteration explain the link?

Get Involved

This 3-year research project began Fall 2018 and is expected to be completed December 2021. The first of 5 projected manuscripts has been published and manuscripts #2 and #3 are in the publication process. The final two manuscripts are expected to be available at the end of the project.

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