Lavender oil and tea tree oil contain compounds that mimic or oppose the actions of sex hormones and may be considered endocrine disruptors. “LO [lavender oil] is the most widely used essential oil in both men and women.” BY JANELLE WEAVER Persistent exposure to lavender products is associated with premature breast development in girls, according to new research by NIEHS scientists. The findings also reveal that chemicals in lavender oil and tea tree oil are potential endocrine disruptors with varying effects on receptors for two hormones — estrogen and androgen. The study was published Aug. 8 in the Endocrine Society’s Journal of Clinical Endocrinology and Metabolism. “These findings demonstrated that the two oils can have hormonal-like effects for estrogen and testosterone in the body,” said senior author Kenneth Korach, Ph.D., lead researcher for the NIEHS Receptor Biology Group. “Lavender oil and tea tree oil could pose potential health exposure concerns and should be researched further, especially because these oils are available without a written prescription from medical professionals and they’re not regulated by the Food and Drug Administration.” Unsafe alternatives? Lavender oil and tea tree oil are among the most popular essential oils used today. “Our society deems essential oils and other … remedies as safe alternatives for medical treatment, personal hygiene commodities, aromatherapy, and cleaning products,” said lead author Tyler Ramsey, who was a postbaccalaureate fellow on Korach’s team. “However, there are many natural products that have effects on the human body, similar to some synthetic drugs.” In a previous study, Korach and his team showed that exposure to lavender oil and tea tree oil is linked to prepubertal gynecomastia, or abnormal breast development in males. Building on these findings in the new study, the team discovered that exposure to lavender fragrance products is also associated with a condition called premature thelarche. This condition causes premature breast development — without other signs of puberty — in girls younger than eight years of age. Over a seven-year period, the clinical colleagues identified 24 patients who were seen for prepubertal gynecomastia or premature thelarche at Nicklaus Children’s Hospital in Miami, Florida….