A new study from the National Institute of Environmental Health Sciences lends new evidence to a suspected link between regular exposure to lavender oil or tea tree oil and prepubertal gynecomastia (abnormal breast growth in young boys).
Ramsey et al identified eight components of lavender and tea tree oils as endocrine disruptor chemicals. Image credit: Ilona Couleur.
Lavender and tea tree oils are among the so-called essential oils that have become popular in the U.S.
The compositions of these oils are comprised of many components and their actions are purported to reduce stress, aid with sleep, and mitigate negative effects of multiple human diseases.
Various consumer products contain these oils, including some soaps, lotions, shampoos, hair-styling products, cologne and laundry detergents.
“Our society deems essential oils as safe. However, they possess a diverse amount of chemicals and should be used with caution because some of these chemicals are potential endocrine disruptors (chemicals that interfere with hormones and their actions in the body),” said lead author J. Tyler Ramsey, a researcher at the National Institute of Environmental Health Sciences (NIEHS), part of the National Institutes of Health.
“Male gynecomastia occurring before puberty is relatively rare, but a growing amount of cases have been reported to coincide with topical exposure to lavender and tea tree oil, and the condition went away after the boys stopped using the oil-containing products.”
NIEHS scientists previously found evidence that lavender and tea tree oil have estrogenic (estrogen-like) properties and anti-androgenic (testosterone inhibiting-like) activities, meaning they compete or hinder the hormones that control male characteristics, which could affect puberty and growth.
For the new study, from the hundreds of chemicals that comprise lavender and tea tree oil, they selected for analysis eight components that are common and mandated for inclusion in the oils.
Four of the tested chemicals appear in both oils: eucalyptol, 4-terpineol, dipentene/limonene and alpha-terpineol. The others were in either oil: linalyl acetate, linalool, alpha-terpinene and gamma-terpinene.
Using in vitro experiments, the scientists applied these chemicals to human cancer cells to measure changes of estrogen receptor- and androgen receptor-target genes and transcriptional activity.
All eight chemicals demonstrated varying estrogenic and/or anti-androgenic properties, with some showing high or little to no activity.
“These changes were consistent with endogenous, or bodily, hormonal conditions that stimulate gynecomastia in prepubescent boys,” Ramsey said.
“Lavender oil and tea tree oil pose potential environmental health concerns and should be investigated further.”
“Of further concern is that many of the chemicals they tested appear in at least 65 other essential oils,” he added.
“Thus, the public should be aware of these findings and consider all evidence before deciding to use essential oils.”
Ramsey and his team reported their results March 19 at ENDO 2018, the Endocrine Society’s 100th annual meeting in Chicago.
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J. Tyler Ramsey et al. Steroid Receptor Hormonal Actions of Lavender and Tea Tree Oil Components. ENDO 2018, abstract # OR22-6
