Abnormal breast growth in young girls is linked to lavender oil exposure, according to a recent study published in the Endocrine Society’s Journal of Clinical Endocrinology & Metabolism.

Previous research has associated breast growth in boys with lavender-containing fragrances. This study, “Lavender Products Associated With Premature Thelarche and Prepubertal Gynecomastia: Case Reports and EDC Activities,” is the first to report abnormal breast growth in young girls.

The researchers found that breast growth in young girls and boys resolved after discontinuing lavender-containing fragranced products. They also determined that certain components of essential oils mimic estrogen and block testosterone, indicating that essential oils could be a source for the breast growth observed in these cases.

“The public should be aware of these findings and consider all evidence before deciding when to use essential oils,” said study lead investigator J. Tyler Ramsey, a second year medical student at Campbell University and postbaccalaureate research fellow at the National Institute of Environmental Health Sciences (NIEHS), part of the National Institutes of Health (NIH). “It’s also important that physicians are aware that lavender and tea tree oils contain endocrine-disrupting chemicals and should be considered in the evaluation of premature breast development in young girls and boys, and the swelling of breast tissue in adult men.”

“It appears that essential oil products have the potential to cause premature breast growth in young girls and boys, so it may be best to discontinue using them on children,” Ramsey said.