Letter to the Editor: “Lavender Products Associated With Premature Thelarche and 1 Prepubertal Gynecomastia: Case Reports and Endocrine-Disrupting Chemical Activities”

I am concerned by the conclusions in this paper by Ramsay et al (1) and in particular the statement “…that physicians are aware that lavender oil (LO) and tea tree oil (TTO) possess endocrine-disrupting chemical (EDC) activities that should be considered in the evaluation of premature breast development in girls and gynecomastia in boys and adult men” when there remains reasonable doubt that it is indeed the essential oils (EOs) that are causing the EDC activity observed. An alternative hypothesis postulated by Carson et al (2) was cited and discussed, however the experimental work described to address this may be insufficient to dismiss the hypothesis.

The authors investigated “…whether the properties of an oil in general could dissolve bisphenol A analogues from the plastic assay plates…” In their comparative analysis of EOs versus fatty oils (corn and soy), they did not appear to appreciate compositional differences of these oils. The possibility that compounds in fatty plant oils have different chemical properties to those found in EOs needs to be considered.

We know that both TTO and LO extract styrene trimers from polystyrene labware at concentrations used in this study and that plastic leachates can affect estrogenic responses of MCF-7 cells (Ishikawa et al) (3). This leaching effect is observably higher in the presence of Dulbecco’s Modified Eagle Medium (DMEM), which was used in this study as well as in the referenced Henley et al study (4).

The authors implicated 2 commercial “aguas” (Crusellas and Mi Tesoro) as having “…the presence of linalool and linalyl acetate as well as unidentified substances.” Samples of both products as well as 3 other aguas based on rankings in popular online platforms (Augustin Reyes, PMB Agua de Violetas, and AFFA Violetas Francescas) were obtained and analyzed by an independent accredited laboratory.

No linalyl acetate was reliably detected in any of these products, while linalool was only detected (2.28%) in the Augustin Reyes product, indicating that LO is not present or is present in such minute quantities to be virtually undetectable. An alternative hypothesis is that a synthetic analogue of LO was used.

The fact that there are, in some instances, significant quantities of compounds with known endocrine-disrupting (ED) properties (5) (3.61% diethyl phthalate in the Mi Tesoro product) was not taken into account, and the authors appear not to have considered the possibility that this substance, which was recorded as “…unidentified substances” may have been a causative factor. Another suspected (6) ED compound (3-[4-(tert-butyl) phenyl]-2-methylpropanal [Lilial]) was detected in 1 product (Crusellas).

A baby shampoo was also implicated. Again, linalyl acetate was not reliably detected, indicating that LO is either not present or is present in such minute quantities as to be virtually undetectable.

We hypothesize synthetic LO analogues were used in all products studied, but the authors did not consider or test for this possibility.

Finally, a new systematic review of the literature (7) was recently published investigating the relationship between TTO, LO, and pediatric endocrine disorders. This paper exonerates TTO and largely exonerates LO as well, concluding, “This systematic review finds that tea tree EO is not related to documented cases of endocrine disruption in children, and that there is little to no evidence to substantiate the proposed link between lavender EO and endocrine disruption in children.”

Abbreviations

Abbreviations
 
• DMEM

  Dulbecco’s Modified Eagle Medium

 
• ED

  endocrine-disrupting

 
• EDC

  endocrine disrupting chemical

 
• EO

  essential oil

 
• LO

  lavender oil

 
• TTO

  tea tree oil

Acknowledgments

Financial Support: No funding was provided for the preparation/submission of this article.

Additional Information

Disclosure Summary: T. Larkman is CEO of the Australian Tea Tree Industry Association (ATTIA Ltd), an Australian based not-for-profit organization formed in 1986 as the peak body to promote and represent the interests of the Australian tea tree industry.

References