The conclusions of the case study...
Our in vitro studies confirm that lavender oil and tea tree oil possess weak estrogenic and antiandrogenic activities that may contribute to an imbalance in estrogen and androgen pathway signaling. Estrogenic or antiandrogenic activities have been reported for other essential oils and some of their monoterpene constituents. On the basis of the three case reports and the in vitro studies, we suspect that repeated topical application of over-the-counter products containing lavender oil or tea tree oil was the cause of gynecomastia in the three patients.
This report raises an issue of concern, since lavender oil and tea tree oil are sold over the counter in their “pure” form and are present in an increasing number of commercial products, including shampoos, hair gels, soaps, and body lotions. Whether the oils elicit similar endocrine-disrupting effects in prepubertal girls, adolescent girls, or women is unknown. Since gynecomastia is labeled idiopathic in approximately 10% of men, one might speculate that unidentified exogenous sources of endocrine-disrupting chemicals may contribute to the onset or progression of the condition, or both, in such patients. The results of our in vitro studies indicate a dose–response relationship in the estrogenic and antiandrogenic activities of lavender oil and tea tree oil, suggesting that susceptibility to gynecomastia or other manifestations of endocrine disruption may require exposure to a threshold dose of these oils. The threshold might depend on several undefined factors, including the concentration of the oil in a product; the duration, frequency, and quantity of use of the product; and the genetic characteristics of persons exposed. Until epidemiologic studies are performed to determine the prevalence of gynecomastia associated with exposure to lavender oil and tea tree oil, we suggest that the medical community should be aware of the possibility of endocrine disruption and should caution patients about repeated exposure to any products containing these oils.
letters section of the Journal for the response from a small portion of the scientific community and encourage you to do a much more thorough job of researching this topic than I have done here. If you're just asking the question, I think this reminds us that we need to be really aware that essential oils aren't just about pretty fragrances but can have a physical effect on us. Essential oils are something most people would consider natural and they show up in all kinds of products, and it reminds us that we need to be very aware of what we're putting in our products regardless of the ingredient's origin.
An additional quick note thanks to a comment made by the Tony Larkman of the Australian Tea Tree Industry Association (www.attia.org.au)...I guess I have to make it clear that I don't think this was a good study and I don't think the conclusions were sound. People are complex creatures, and I don't think it's possible to come to the conclusion that these essential oils were the cause of the boys' physical issues with such little information. I thought my opinion would have been obvious from the context, but apparently I need to spell things out these days or I get nasty comments from people with financial interest in the ingredient. (If you want to dispute something I've written, here are some suggestions for how to do it and be nice about it.)
I suspect Tony's new to the blog - he probably does a regular search for mean things written about tea tree oil and found what he thought was a slam of his product, instead of being a regular reader who would know about my perspective on science and how I write. He probably didn't bother to scroll back to December 3 to 6th to see all the nice things I've said about tea tree oil and all my suggestions for ways we could use his essential oil in our products. I'm guessing he probably didn't bother to familiarize himself with my blog before making a comment.
His comment (which you can read in the comment section of this post): "It is intensely frustrating for the tea tree industry that this statement is still being promulgated in articles such as these without any evidence to back up the statement except poor science."
A final thought...Does what he has written with his link and company information constitute advertising on my site? He could have written his opinion without putting that information in his comment. It wasn't essential to the post. What do you think?
And thus endeth the rant...
Join me tomorrow as we take a look at another essential oil!