Essential oils: renewal of interest and toxicity.

Essential oils are complex mixtures of substances from vegetable matter, the definition of which is based on their method of extraction. They are characterized by their ambivalence, their ambiguity and their disparity: plant families from which essential oils are extracted are numerous; the composition of each essential oil depends not only on the family but also on the part of the plant from which it is extracted, and sometimes on the soil where the plant grows, or even on the time of the harvest. Gas chromatography is therefore necessary to characterize an essential oil. Essential oils can be found in cosmetics, in drugs, and in food. They are natural substances, but natural is not synonymous with harmless. Evaluation of the toxicity of essential oils and European regulation are underway.