The same day I wrote a recommendation for a soap containing tea tree oil, I heard from a pharmacist about a paper that suggested a possible link between the use of products containing lavender and tea tree oils and gynecomastia (breast enlargement) in young boys. Only 3 cases prompted the study, but the researchers also did in vitro studies demonstrating endocrine disruption activity by both lavender and tea tree oils. And, when the each of the boys ceased using the personal care products with those oils, the gynecomastia resolved. (I should note that the only oil all of the boys used was lavender; only one of the boys used a product containing tea tree oil, and that product also contained lavender.)
http://www.nih.gov/news/pr/jan2007/niehs-31.htm
The NIH letter was careful not to draw any conclusions, it merely alerted the medical profession to the study. Per the study author, there still is much work to be done to draw any conclusions. As always, the issue of exposure strength and duration is a big question mark when it comes to applying this study more broadly. (I would personally want to know if the products were detergent products – probably so, one definitely was – another factor in exposure because of increased membrane permeability.) And there are other endocrine disruptors in most modern environments, such as plasticizers, which were not concurrently studied or considered and could be an additive factor.
The pharmacist who wrote me said her professional opinion would be for parents to avoid products with these oils (lavender and tea tree oil). Children do have more permeable skin than adults.
In the interest of providing as much perspective as possible, I am also including a link to an article by respected naturopath Dr. Randall Neustaedter. It discusses both sides of the issue regarding tea tree oil. [link]
Allergic contact dermatitis to tea tree oil is another potential concern [link 1][link 2], if anything, more well-documented than the above.
All I have to say is that I believe in erring on the side of caution with kids.
I am amazed at how many times an uproar can be created by the media over inadequate information. The study does in fact cover only one individual who used a product containing tea tree oil, and including that one, three boys who used a lavender based product.
The largest single problem with the study is the fact that no other environmental factors were taken into consideration. Diet, exercise, weight, and other factors were ignored. There are quite literally hundreds of everyday foods with higher levels of phytoestrogens, including the most highly estrogenic soy and licorice products.
The Australian Tea Tree Industry Association has written an incredibly well thought out reply to the gynecomastia study. You can read it and other myths concerning tea tree oil at,
http://www.tea-tree-info.com/myth.html
Thank You.