Evaluation of Placental Toxicity of Five Essential Oils and Their Potential Endocrine-Disrupting Effects

Abstract

Pregnant women may use EOs in case of morning sickness, nausea, stress management, etc. Little is known about the potential danger that EOs represent for the placenta and therefore for the pregnancy. Our aim was to explore and compare the placental toxicity and potential endocrine disrupting effects of niaouli, orange, tea tree, wintergreen and ylang-ylang EOs, and their key compounds: 4-terpineol, 1,8-cineol, limonene, methyl salicylate and benzyl salicylate. We studied the release of four hormones and the activation of P2X7 receptor in JEG-Tox human placental cells as key biomarkers for endocrine toxicity. We observed that niaouli, orange, tea tree, wintergreen and ylang-ylang EOs and their key components disrupted at least one of the studied hormones but none of them activated the P2X7 cell death receptor. The tested EOs appear then to be more hormonal modulators rather than EDCs in human placental cells. The hormonal effects observed with the key components were very different from those observed with the EOs. EOs are very complex mixtures, and it is essential to study whole EOs rather than their components individually in safety assessment.

Advancing Endocrine Disruptors via In Vitro Evaluation: Recognizing the Significance of the Organization for Economic Co-Operation and Development and United States Environmental Protection Agency Guidelines, Embracing New Assessment Methods, and the Urgent Need for a Comprehensive Battery of Tests

“…The h-Placentox test is based on the activation of the P2X7 receptor as an in vitro marker of adverse health effects and the dosage of hormones. It has been used to evaluate forskolin, a diterpene from a plant used in food supplements for weight loss [ 60 ], essential oils [ 61 ], and chlorpyrifos, a persistent and bioaccumulative worldwide banned pesticide [ 62 ].…”

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

“…25 Indeed, in an in vitro assay using placental cells, eucalyptol and limonene decreased E 2 production, while 4-terpineol increased progesterone and E 2 secretion in a doseindependent manner. 26 Again, as with the other studies summarized above, it is not possible to extrapolate the in vitro findings to the in vivo situation where absorption, distribution, metabolism and excretion exert dominant roles on tissue exposure and response.…”

“…[29][30][31][32] Possible antiandrogenic effect on hair growth in hirsute women with topical application. 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.…”

Phytoestrogens and Health Effects

“…These molecules are particularly concentrated in the essential oils of medicinal plants including clary sage, peppermint, chamomile, and niaouli [ 43 , 44 ]. A recent in vitro study, having examined the estrogenic potency of several medicinal plants by using a human placenta model, points to anethole as one of the most estrogenic molecules [ 45 ]. Anethole is a phenylpropene that confers estrogenic effects to fennel and other Apiaceous plants (such as star anise and cumin) that are widely present in traditional medicine or have culinary uses in many countries as spices or seed teas; they are used for their beneficial effects on digestion, intestinal spasms, and premenstrual symptoms, or to stimulate lactation.…”