**7. Endocrine disrupting potential of essential oils**

In the last decade, there has been an accumulation of evidence suggesting a possible endocrine disrupting effect of some essential oils. Initially, a report signaled the apparition of idiopathic male prepubertal gynecomastia in patients with topically applied lavender oil or tea tree oil [36]. The experimental data showed that both lavender oil and tea tree oil effects are produced by the activation of estrogenic receptors (ER), with a potency of 50% of estradiol, being attenuated in the presence of fulvestrant, a pure antagonist of ER receptors.

Recently, another study published in 2019, confirmed the mentioned data, showing that a continuous exposure to lavender-fragranced products induced a

**49**

**Figure 5.**

*Chemical compounds responsible for the abortifacient effect.*

*Safety Profile of Essential Oils*

these findings [37].

understood.

[13, 38].

[12, 38].

*DOI: http://dx.doi.org/10.5772/intechopen.91363*

**8. Essential oils in pregnancy and lactation**

royal oil case) or even death [12, 38].

premature thelarche in four patients [37]. The chemical constituents from the essential oils were individually tested concerning their capacity of stimulating ERα estrogen response element (ERE)-mediated activity. The most active compounds with estrogenic activity were α-terpineol, 4-terpineol and linalool. Further research on a more statistically significant population is needed to confirm the relevance of

The main concerns of the use of essential oils during pregnancy is related to the risk of chemical compounds crossing the placental barrier with direct effects on the product of conception, but also to the direct abortive effect. The use of essential oils during pregnancy is a controversial topic and one that is yet to be fully

Some essential oils are abortifacients, being capable of inducing miscarriage/ abortion. Essential oils like persil oil (*Petroselinum sativum*) rich in apiole, pennyroyal oil (*Mentha pulegium*) rich in pulegone, plectranthus oil (*Plectranthus amboinicus*), Spanish sage oil (*Salvia lavandulifolia*) or savin oil (*Juniperus sabina*) rich in sabinyl acetate should be avoided during pregnancy (**Figure 5**). The amounts required to induce an abortion may also pose toxicity risks to the mother, including kidney and liver damage (could be the reason of pregnancy termination in penny-

Due to their chemical properties (low molecular weight, lipophilicity), it is likely that certain essential oil components could cross the placental barrier, reaching fetal circulation. Following a possible biotransformation into polar molecules, they can accumulate in the fetus due to a reduced glomerular filtration rate and low content of plasma proteins capable of binding xenobiotics

Essential oils should not be used in pregnancy (or breastfeeding) if they contain

large amounts of the following components: (E)-anethole (aniseed-*Pimpinella anisum*, star anise-*Illicium verum*, fennel-*Foeniculum vulgare,* dill-*Anethum graveolens*), apiole (persil-*Petroselinum sativum*), β-eudesmol (cypress-*Cupressus sempervirens*), camphor (Spanish lavender-*Lavandula stoechas*), methyl salicylate (sweet birch-*Betula lenta*), pinocamphone (hyssop-*Hyssopus officinalis*), or thujone (mugworth-*Arthemisia vulgaris,* savin-*Juniperus sabina,* thuja-*Thuja occidentalis*)

*Essential Oils - Bioactive Compounds, New Perspectives and Applications*

activated GABAA receptors in laboratory animals [34].

*Chemical structure of terpenes with epileptogenic potential.*

**7. Endocrine disrupting potential of essential oils**

ence of fulvestrant, a pure antagonist of ER receptors.

The identified chemical constituents responsible for convulsions were usually 1,8-cineole, camphor, thujone, pulegone and pinocamphone (**Figure 4**) [29, 30]. Molecular mechanisms of the convulsant effect of essential oils and their constituents were investigated in laboratory animals. According to a study, some essential oils resemble pentylentetrazole, a powerful convulsive agent, modifying tissue gradients of Na and K and leading to increased cellular excitability in the brain [32]. In another experimental study, thujone one of the frequently incriminated pro-convulsant terpenes, suppressed GABA-induced peak currents in rat dorsal root ganglion neurons, with the subsequent apparition of convulsions, terminated by diazepam or phenobarbital [33]. On the contrary, other research proved that different terpenes could have an anticonvulsant effect. Menthol, another terpene derivative found in the chemical composition of some essential oils enhanced electric currents induced by low concentrations of GABA and directly

In the context of potential neurological toxicity of essential oils, European Medicines Agency (EMA) reviewed the safety of suppositories containing terpenes used in seven European countries (France, Belgium, Portugal, Spain, Italy, Luxembourg and Finland) for the treatment of respiratory diseases. The report concluded that terpenes could induce convulsions in children less than 30 months, recommending they should be contraindicated in this particular segment of

In the last decade, there has been an accumulation of evidence suggesting a possible endocrine disrupting effect of some essential oils. Initially, a report signaled the apparition of idiopathic male prepubertal gynecomastia in patients with topically applied lavender oil or tea tree oil [36]. The experimental data showed that both lavender oil and tea tree oil effects are produced by the activation of estrogenic receptors (ER), with a potency of 50% of estradiol, being attenuated in the pres-

Recently, another study published in 2019, confirmed the mentioned data, showing that a continuous exposure to lavender-fragranced products induced a

**48**

patients [35].

**Figure 4.**

premature thelarche in four patients [37]. The chemical constituents from the essential oils were individually tested concerning their capacity of stimulating ERα estrogen response element (ERE)-mediated activity. The most active compounds with estrogenic activity were α-terpineol, 4-terpineol and linalool. Further research on a more statistically significant population is needed to confirm the relevance of these findings [37].
