Even though the story is all over the news and the Internet, there is actually only ONE study that makes these claims. So, I took a closer look at the study.
Originally published in the New England Journal of Medicine, the study details three young boys who had developed gynecomastia (breasts). The doctors treating the boys learned that each of them were using products with lavender or tea tree essential oils, and once they stopped using these products, the breasts went away. The researchers then took these case studies and decided to test the essential oils on human tissue in a lab. According to their study, the essential oils acted estrogenically, and thus could have been the cause of the breast development in the boys. However, I, along with numerous researchers and doctors have found some major flaws in the study.
Before I get in to more specifics--just a quick note. Looking at the footnotes of the study, you'll notice that all of the doctors who conducted the research are sponsored by numerous drug companies. 'Nuff said.
Three doctors (Kathi J. Kemper, M.D., M.P.H., Wake Forest University School of Medicine, Winston-Salem, NC 27157; Aviva J. Romm, Yale University School of Medicine, New Haven, CT 06510; Paula Gardiner, M.D., M.P.H., Harvard Medical School, Boston, MA 02215) wrote a commentary on the study:
The study by Henley et al. (Feb. 1 issue)1 raises many questions. Product names were not provided. Did the authors contact manufacturers to report concerns or ask about constituents? The variability, adulteration, and contamination of herbal products have been widely reported,2,3 as have discrepancies between labels and contents.4 Plastic containers may contain phthalates, known endocrine disrupters.5 What was actually in the products cited in this report?The doctors bring up a few great points here, number one in my book is, what other estrogen mimickers were present in these products used on the young boys? Parabens? Phalates? The ingredients are not documented and could be a number of things--even from using bottles made with BPA.
None of the hormonal testing showed abnormal results, except in Patient 2, who had elevated levels of testosterone (not estrogen). There was no report on ultrasound examination or needle biopsy, nor were subsequent weight changes reported. Might the patients' gynecomastia have reflected another pathophysiological process that resolved spontaneously?Traditional use and clinical trials have not suggested estrogenic effects of tea tree or lavender oil, though estrogenic effects have been reported for other essential oils and plants. Are occupational exposures to lavender and tea tree associated with estrogenic symptoms? In vitro testing alone is not adequate grounds for indicting traditionally used products and may raise public fear.
But what about the laboratory tests they did on petri dishes of human cells? If you look carefully at their study, you'll notice they didn't apply pure lavender or tea tree essential oil on the cells they were testing, they used a solvent to dilute the oils. The solvent is dimethylsulfoxide---which, as it turns out, is an estrogen mimicker! (as documented here.)
The bottom line is that lavender and tea tree essential oils have been used for thousands of years with no history or evidence of estrogen mimicry. They're probably the most widely used essential oils in baby products, so of course the three boys in the study were using them. If lavender and tea tree essential oils were truly estrogen mimickers, we would have known about their effects long ago.