|Date: 02-15-2017||HC# 081612-562|
Dornic N, Ficheux AS, Roudot AC. Qualitative and quantitative composition of essential oils: a literature-based database on contact allergens used for safety assessment. Regul Toxicol Pharmacol. 2016;80:226-232.
Despite the popularity of essential oils (EOs), there is limited information on the safety of these natural products. EOs consist of a mixture of many different chemicals, including some allergens, but they do not have the same safety requirements as cosmetics. This lack of regulation puts many consumers at risk. The aim of this study was to present a literature-based database that included quantitative and qualitative information about chemical allergens found in EOs.
There were 11 EOs included in this study, which was based on information obtained from previous research conducted with 1,507 French subjects.1 Qualitative and quantitative data (plant species, EO, and composition) were obtained by searching the PubMed and ScienceDirect databases, as well as the Journal of Essential Oil Research.
The raw data were collected and transformed into probabilistic data in three different steps as follows: (1) For each EO, the relative concentrations of known chemical allergens (limited to those that had sufficient human evidence for their effects) were compiled. The probability of occurrence was considered the same if more than one species was associated with each EO. (2) The data were sorted in ascending order, and the respective probabilities of occurrence were calculated. The number of occurrences of each concentration was then divided by the amount of data (assays) collected for each EO. (3) All this data were processed into a discrete-type density of probability using a specific software program. Based on this information, skin sensitization risk assessments could then be made from calculations that considered specific dose exposure per unit area.
All the different EOs and their associated species assessed in this study are provided in Table 1 at the end of the HerbClip. A total of 517 assays from 112 publications were used to provide information for probabilistic exposure assessments. A total of 22 substances were recognized as established contact allergens from the EOs. The percentage of relative occurrence for chemical allergens in EOs included the following: 82% for pinene, 79% for limonene, 60% for α-terpineol, 58% for β-caryophyllene, and 38% for terpinolene. The chemical allergens vanillin and cinnamyl were excluded from these results because they were present only in one EO (vanilla and ylang ylang, respectively). The EO that contained the most allergens was ylang ylang, with a total of 16 identified. In descending order, this was followed by eucalyptus (15), citrus (12), lavender (11), mint (11), belbowrie (niaouli) (11), rosemary (10), pine (10), camphor (ravintsara) (8), tea tree (7), and vanilla (1). Pinene, one of the top three allergens, was found in seven EOs, and the allergen cineole was found in six EOs. The table with EOs, Latin binomials, and family names is given below.
An example was provided on how the database could be used. This was demonstrated by assessing cineole exposure on the feet of two subjects that had participated in the previously mentioned French study.1 In this example, a male subject was more exposed than a female to cineole although both used a similar amount of EO drops (four for the male and three for the female). Several parameters may explain this finding—the two subjects did not use the same type of EO on their feet and the way they used the EO differed, with the male using EOs directly on his skin weekly, while the female applied them with a cloth occasionally (not weekly).
According to the authors, this study is the first of its kind to assess allergen exposure from several EOs. The authors also point out that aggregate exposure of cosmetics with aromatherapy products could be an additional health concern. For example, both linalool and limonene are common in cosmetics, and according to this study, are also prevalent in EOs. Although this study examined only 11 EOs, and could have been more comprehensive, this research provides a useful tool for skin sensitization risk assessments and may serve as a model for future studies on EO allergens.
—Laura M. Bystrom, PhD
Reference1Dornic N, Ficheux AS, Roudot AC, Saboureau D, Ezzedine K. Usage patterns of aromatherapy among the French general population: a descriptive study focusing on dermal exposure. Regul Toxicol Pharmacol. 2016;76:87-93.