Contact urticaria from geraniol

Ubiquity, Hazardous Effects, and Risk Assessment of Fragrances in Consumer Products

Purpose of review

The main aims of fragrances are to create pleasing scents or to mask unpleasant odors. We hereby review their main exposure sources, presumed benefits, and unwanted effects, with special attention to allergic contact dermatitis (prevalence, regulatory environment, risk assessment methodology, and preventive measures).

Recent findings

Fragrances elicit positive emotions and presumably have therapeutic benefits related to stress reduction and memory enhancement. However, they also cause detrimental health or environmental effects including contact dermatitis (irritant and/or allergic), non-eczematous contact reactions, photosensitivity, photo-allergy, and immediate contact reactions, which can negatively impact the quality of life. Fragrances are the most frequent chemicals causing contact dermatitis. Their main sources are cosmetics, household products, industrial substances, food flavorings, oral hygiene products, and topical medications. It is difficult for sensitized patients to avoid contact with fragrances, due to their ubiquity and because manufacturers are not willing to volunteer information regarding fragrance ingredients.

Summary

The treatment of contact dermatitis relies on allergens avoidance which does not “cure” the disease (sensitization persists for life) but prevents disabling illness. The patient should understand that avoiding perfume means to avoid all scented goods and not just perfumes.

Labeling fragrances is key in primary prevention (by giving the healthy individual the chance to make an informed choice to avoid risky substances), diagnosis (by helping the practitioner to plan and interpret patch tests), secondary prevention, and prognosis (by allowing the sensitized patient to follow the avoidance instructions). However, only 26 fragrances are mandatory to be declared in cosmetics. The vague labeling of other fragrance ingredients as “perfume” or “fragrance” hampers the diagnostic and preventive approaches. Therefore, in our opinion, declaration should be mandatory for all fragrance ingredients as well as straightforward so most consumers can understand it. Moreover, legislation should be improved to prevent inappropriately high exposures by forbidding stronger allergens, restricting maximum concentrations in the finished product or fields of application, delivering information regarding the risks to the general public, and controlling the compliance of manufacturers with the regulations. Besides, manufacturers should share information regarding the composition in the final products and provide physicians with samples of all fragrance chemicals whenever needed for patch test investigations.

Allergic contact dermatitis caused by farnesol: clinical relevance

CONTEXT

The fragrance material farnesol is cited as an infrequent but important cause of allergic contact dermatitis (ACD). It is included in the fragrance mix II patch series and requires labeling in the European Union if it is used in a consumer product.

OBJECTIVE

To review the existing literature to determine the causative role of farnesol in clinical contact allergy.

MATERIALS AND METHODS

Survey of the literature on farnesol studies; predictive and clinical elicitation tests in case reports, reviews, and abstracts.

RESULTS

Predictive animal studies demonstrated in most cases that farnesol was a nonsensitizer. However, 2 local lymph node assays (LLNAs) indicated strong sensitization potential. Predictive human test data indicated a low potential, if any, for sensitization in human tests with farnesol at 10% or 12%. A few clinical reports indicated low-level allergy or questionable reactions to farnesol, with 5% being the most commonly used. There were also reports in which no reactions were seen.

DISCUSSION

Predictive testing on farnesol in animals shows conflicting results depending on the study methodology used. Human predictive patch-test data also had gaps that prevented it from being definitive in pointing to a causative relationship between farnesol and contact dermatitis. The real sensitizing potential of a material can best be determined by evaluating the clinical and epidemiological data so as to help resolve the conflicting animal and human predictive test data.

CONCLUSIONS

This literature and scoring exercise showed that predictive and clinical elicitation data do not document a clear causative determination that farnesol is a frequent contact allergen. Detailed clinical relevance and patient studies should clarify the clinical problem farnesol represents.