Researchers from the National Institute of Environmental Health Sciences (NIEHS) report that repeated topical use of products containing lavender oil or tea tree oil may cause enlarged breast tissue in boys prior to puberty. Triggers for the condition - known as prepubertal gynecomastia - had not been previously identified. The finding was made after three young male patients with prepubertal gynecomastia presented at the University of Colorado's School of Medicine. The researchers subsequently found an association between the use of products containing lavender and tea tree oil and the rare disorder. Reporting their findings in the New England Journal of Medicine, the researchers cautioned that more research is needed and at this point, the findings are only applicable to young males with unexplainable enlarged breasts who are regularly using products containing these essential oils.
The boys, aged between four and ten, had normal hormonal levels when they were diagnosed with gynecomastia. However, it was noted that all had either used lavender-scented soap and skin lotions, or shampoos or styling products that contained tea tree oil and lavender oil as ingredients. In each case, several months after the suspected products were discontinued; the gynecomastia had subsided or disappeared.
Wanting hard evidence to establish the association, the researchers conducted experiments using human cells to determine if the oils mimic the effects of the female hormone estrogen, or inhibited the effects of androgens (male hormones) known to control masculine characteristics and inhibit the growth of breast tissue. "The results of our laboratory studies confirm that pure lavender and tea tree oils can mimic the actions of estrogens and inhibit the effects of androgens," said researcher Ken Korach. "This combinatorial activity makes them somewhat unique as endocrine disruptors."
These essential oils might now be considered endocrine disruptors since they appeared to have caused an imbalance in estrogen and androgen signaling. Endocrine disruptors are naturally occurring compounds or synthetic chemicals that may interfere with the production or activity of hormones of the endocrine system leading to adverse health effects.
"We want to encourage doctors who may be seeing patients with gynecomastia to ask their patients about the products they are using. Patients with prepubertal gynecomastia may want to consider reducing the use of products that contain these oils," concluded Korach.
Based on material from the National Institute of Environmental Health Sciences
