The French Agency for Food, Environmental and Occupational Health & Safety (ANSES) said these oils could pose certain carcinogenic, genotoxic and potentially reprotoxic risks if recommended dosage and storage instructions are not followed.
To further avoid these risks, the Agency advises against their consumption for children and pregnant or breastfeeding women.
“Consumers are diverting the use of tea tree, niaouli and cajeput to make additional treatments to treat certain infections,” the Agency states.
“However, these essential oils are not recommended or even prohibited in certain European countries because of their potential neurotoxic effects. ANSES was therefore asked to study the risks associated with their ingestion.”
Derived from the leaves of different species of Melaleuca, tea tree oil in particular is the main ingredient of topical antibacterial products.
Tea tree oil is commonly used for acne treatment, reducing inflammation and may be effective in the addressing fungal infections such as Athlete's foot.
Along with niaouli and cajeput, tea tree oil has been used in the past as adjunct treatments to treat certain infections such as tonsillitis, sinusitis and cystitis.
Disharmony at European level
Melaleuca-based essential oils are authorised for use in Italy but prohibited in Belgium in a prime example of inconsistent regulation governing their use in food supplements at the European level and from country to country.
In its guidance, ANSES flags a number of substances contained in these essential oils. For tea tree, terpinen-4-ol is a major component that in studies was linked to testicular toxicity in rats.
Although present in very small quantities methyl eugenol is considered genotoxic and carcinogenic to humans, while ascaridole is a substance that appears if the tea tree oil is not properly maintained and whose toxicity is not well documented.
For niaouli and cajeput, the Agency points to 1,8-cineole as the oil’s main constituent, which has been linked to neurological complications in children. It is also present in essential tea tree oils but at lower concentrations.
“For tea tree oil, the health risk associated with terpinen-4-ol and methyl eugenol depends on the contents of these compounds in essential oils, the number of drops consumed, the size of the drops delivered by the dropper bottles and of the consumer's body weight,” ANSES’ findings conclude.
“However, uncertainties remain about the toxicity of ascaridole and its presence in products on the market.
“For niaouli and cajeput, the data on 1,8-cineole are insufficient and do not allow a level of exposure to be defined without risk for the consumer.”
Storage, dosage, elimination and prohibition
The Agency’s findings also extend to the oil’s storage, dosage, elimination and prohibition with ANSES recommending operators involved with tea tree oil take steps to determine the maximum number of drops to consume per day considering terpinen-4-ol and methyl eugenol content.
ANSES also recommends action be taken on determining the size of the drops delivered by the vials and the consumer body weight.
The Authority also advises ways to minimise the formation of ascaridole, in which the consumer must be informed that the tea tree oil must be stored in a cool and dark place.
For essential oils of niaouli and cajeput rich in 1,8-cineole, ANSES does not recommend its oral consumption in children under 30 months or children with a history of epilepsy or febrile convulsions, as the Agency said it was awaiting further toxicological data.
“For children, pregnant or breastfeeding women, ANSES underlines the absence of specific data relating to the risks associated with the consumption of these three essential oils orally and advises against their consumption.”