Association of Early Pubertal Onset in Female Rats With Inhalation of Lavender Oil

Abstract

Background Central precocious puberty (CPP) is caused by early activation of the hypothalamic–pituitary–gonadal axis but its major cause remains unclear. Studies have indicated an association between chronic environmental exposure to endocrine-disrupting chemicals and pubertal onset. Essential oil is widely used in homes worldwide for relief of respiratory symptoms, stress, and/or sleep disturbance. Methods To evaluate this association, we compared the hormone levels and timing of vaginal opening (VO) in female rats exposed to lavender oil (LO) through different routes (study groups: control, LO nasal spray [LS], and indoor exposure to LO [LE]) during the prepubertal period. The body weights of the animals were also compared every 3 days until the day of VO, at which time gonadotropin levels and internal organ weights were assessed. Results The LS group showed early VO at 33.8 ± 1.8 days compared with the control (38.4 ± 2.9 days) and LE (36.6 ± 1.5 days) groups. Additionally, luteinizing hormone levels were significantly higher in the LE and LS groups than those in the control group. Body weights did not differ significantly among the groups. Conclusion Inhalation exposure to an exogenic simulant during the prepubertal period might trigger early pubertal onset in female rats. Further evaluation of exposure to other endocrine-disrupting chemicals capable of inducing CPP through the skin, orally, and/or nasally is warranted.

Are Prepubertal Gynaecomastia and Premature Thelarche Linked to Topical Lavender and Tea Tree Oil Use?

“…Indeed, the authors thought that the mechanism of action was probably through olfactory stimulation of the hypothalamus, rather than a hormonal effect. 28 In contrast to the above studies showing no in vivo oestrogenic effect of LO, Slighoua and co-workers reported an increase in uterine weights and serum E 2 levels of female rats treated with hydro-ethanolic extracts of Lavandula officinalis Chaix. 29 These extracts contained phenolic compounds, but it is unknown whether they also contained linalool or linalyl acetate, as found in LO.…”

“…1 Along with the three initial patients described by Henley et al, an additional nine patients who were reported to use a product containing LO or TTO were subsequently diagnosed with either prepubertal gynaecomastia (total n=8) or premature thelarche (n=4) (Table 2). 1,2,[27][28][29] Three of the eight boys had Tanner genitalia staging, and all were stage 1. Eight of the twelve children also had Tanner pubic hair staging.…”

“…26 Studies with rodents show conflicting effects. 23,26,28,30 Analogy Yes Yes There are several examples of premature breast development in children exposed to oestrogen-containing products. 4 LO = lavender oil; TTO = tea tree oil.…”