Here is the best I could find, from Endocrinenews: A Publication of The Endocrine Society AUGUST 2006, sorry for the poor formating, I copied the text from a pdf.
GYNECOMASTIA in Prepubertal Boys ?
By Eric Seaborg*
- Eric Seaborg is an award-winning writer living in Charlottesville, Va.
Lavender and tea tree oil in health and beauty products can alter estrogen and androgen activity to such an extent that they evidently contributed to enlarged breast tissue in
three prepubertal boys, according to a study by Derek Henley, Ph.D., and colleagues
at the National Institute of Environmental Health Science (NIEHS) in Research Triangle Park, N.C. The researchers were drawn to examine lavender because several young male patients presented with idiopathic prepubertal gynecomastia. All had used over-the-counter products such as shampoos, hair gels, and lotions containing lavender oil and, in one case, also tea tree oil. Prepubertal gynecomastia is associated with an imbalance
of estrogens and androgens, but the three boys examined closely had normal estrogen levels in their blood, indicating that increased estrogen was not responsible for their condition. When the boys stopped using the products containing the oils, their breast size decreased, suggesting that components in these products were contributing to the prepubertal gynecomastia. Lavender, tea tree, and similar so-called ?essential oils? are widely used in health care products, but there is little information on their health impact in humans. The NIEHS researchers devised a way to evaluate their estrogenic and
antiandrogenic activities in vitro using two human breast cancer cell lines. They tested the estrogenic activity of lavender and tea tree oil using MCF-7 cells and found that both
oils increased the activity of an estrogen-responsive reporter plasmid in a dose-dependent fashion. The responses were attenuated in the presence of an estrogen-receptor antagonist, indicating that the oils activated the reporter plasmid through an estrogen receptor?dependent pathway. In further experiments, both oils induced changes in endogenous mRNA expression of several estrogen-regulated genes, again in an estrogen receptor?dependent manner. The researchers then used MDA-kb2 cells transfected with
an androgen-responsive reporter plasmid to evaluate the oils? antiandrogenic activity. The oils showed weak antiandrogenic activity and also inhibited androgen-stimulated endogenous gene expression. Taken together, these results provide evidence that lavender
and tea tree oils exhibit estrogenic and antiandrogenic activities in vitro, and may explain the cases of these males with prepubertal gynecomastia. Dr. Henley, a postdoctoral fellow, said his team?s goal in publicizing these findings was to ?make patients and physicians aware of the association,? but that it was too soon to draw any firm conclusions. He would like to see an epidemiological study on much larger populations of patients with idiopathic prepubertal gynecomastia. ?The study might shed light on whether genetic or environmental factors may also contribute to this effect, or if it is solely due to exposure to these essential oils,? Dr. Henley said. The findings were presented in Boston at ENDO 2006, The Endocrine Society?s 88th annual meeting. Edward Reiter, M.D., chair of the department of pediatrics at Tufts University School of Medicine, moderated the press conference about the study and he agreed with Dr. Henley?s assessment. Dr. Reiter called the ?sleuthing work? by pediatric endocrinologist Clifford Bloch, M.D., at the University of Colorado School of Medicine, who identified the association of the oils with gynecomastia ?outstanding,? and said the issue deserves attention. ?People are constantly exposed to all sorts of agents that are estrogenic or antiestrogenic or androgenic or antiandrogenic. The whole issue is alarming,? Dr. Reiter said. ?Whether this particular situation is of concern is not clear; it is too early to know if these oils are really widely used and whether other young boys or young girls have had similar episodes of breast development. We need more research.?