Fragrance allergy
Authors: M.H. Beck
Journal: British Journal of Dermatology (2000)

Fragrances are ubiquitous and contact allergy is common, affecting in the region of 1% of the population. 1 In general, fragrances are the second most common class of substances identified as causing an allergic positive patch test in patients attending clinics specializing in contact dermatitis investigation. 2 Analysis of affected individuals has shown that the common patterns of dermatitis are hands and face in women; hands, face and lower legs in men 3 and axillae in both sexes. 4 Connubial allergy is well recognized and allergy to lavender applied to a pillow was recently described. 5 Many may suspect their allergy, but there is still a substantial number who don't. Furthermore, those who are aware of their allergy may continue to have problems by failing to take appropriate avoidance measures, in particular, unwittingly applying perfumed medicaments and cosmetics to their skin. European legislation has helped by requiring full ingredient labelling, perfume being identified as 'parfum' in the International Nomenclature of Cosmetic Ingredients [INCI]. Nevertheless, we still see many patients carrying cosmetics and medicaments without this important piece of information on the package. The investigation of fragrance allergy is made no easier by the fact that the perfume may contain over 300 fragranced components and, in addition, fixatives are used to influence the quality and persistence of the perfume. Little is known of the dose–response relationship and threshold for expression of contact allergy in relation to fragrance ingredients. Furthermore, the mystique of commercial secrecy has hindered progress in our understanding of fragrance contact allergens. Self-regulation and monitoring is undertaken by the perfume industry through the International Fragrance Association [IFRA]. Their Code of Practice restricts the use and concentrations of certain fragrance ingredients with a sensitizing potential. The Research Institute of Fragrance Materials [RIFM] also has a role by performing research to establish the safety of fragrances. Historically, before 1977 there were two recommended markers in the standard series of patch tests to alert clinicians to the possibility of perfume allergy – Balsam of Peru 6 and Wood Tars. 7 However, Wood Tars are no longer recommended and Balsam of Peru was reckoned to identify only 50% of fragrance allergic subjects. 8 A major improvement was achieved as a result of Walter Larsen's in-depth investigation into allergy from the perfume used in Mycolog® Cream. 9 He proposed a mix of cinnamic alcohol, cinnamaldehyde, hydroxycitranellol, amyl cinnamaldehyde, geraniol, eugenol, isoeugenol and oak moss absolute, each at 2% in petrolatum. However, this gave some false positive reactions and the mix has been changed to 1% of each of these components, and an emulsifier, sorbitan sesquioleate, has also been added to the commercial patch test reagent. This has increased the detection rate to 70–80%. 10 The allergic response rate to the mix ranges from 6 to 11% in patients attending for contact dermatitis investigation. 2 There are still instances of false positive reactions, but some of these may be explained by compound allergy and, perversely, there are also false negative reactions, some of which are blamed on the phenomenon of quenching, whereby some components of the mix mask the allergenic elements of others. 11 This effect has, however, been questioned. 12 Attempts continue to be made to improve the mix and identify other components of perfumes liable to induce allergy. Many reports of perfume allergy are sporadic or anecdotal. There is, nevertheless, evidence that 4-[4-hydroxy-4-methylpentyl]-3-cyclohexine carboxyaldehyde [Lyral®] is an important perfume sensitizer, accounting for 2·7% of patients' allergies in a large European multi-centre trial: this group has recommended testing at 5% in petrolatum in patients suspected of contact dermatitis. 13 In 1986 the North American Contact Dermatitis Group extended their perfume screening series by testing not only to the individual fragrance mix components, but also with anisyl alcohol, benzyl alcohol, benzyl salicylate, coumarin, musk ambrette and sandalwood oil. 14 Other attempts have been made to improve on fragrance mix to screen for fragrance allergy but, as far as I am aware, these suggestions have not been widely instigated in contact dermatitis investigation centres. It is well recognized that allergens wax and wane in importance as a result of changes in fashion and population exposure. There is evidence of an increase in the prevalence of fragrance allergy in some countries. 15 Trends come and go and this is true with regard to the type and quality of perfumes. It is important that this is monitored. In this month's British Journal of Dermatology, Buckley et al. have shown a dramatic reduction in cinnamic aldehyde and cinnamic alcohol allergy over the last 17 years. They suggest that this has occurred because concentrations of these materials have been reduced in cosmetic products, or combined with quenching agents. The overall rate of fragrance allergy has nevertheless remained unchanged. They conclude by stating that exact ingredient labelling, a decrease in the number of items containing perfume allergens at sensitizing concentrations, and an increase in availability of fragrance-free products might all contribute to a reduction in the frequency of this problem. What about the future? There can be no doubt there have been great steps forward as a result of full ingredient labelling on the packaging of products, and this has enabled dermatologists to give rational and accurate advice to consumers on avoiding materials to which they are allergically sensitized. However, as the composition of the perfumed element of cosmetics to which the population is exposed is unknown, the data presently collected in relation to fragrance exposure and allergy is incomplete. Monitoring is therefore inadequate. There is future potential to alter perfume composition by removing or lowering the concentrations of allergens, adding quenching agents and making allergen substitutions. Suggestive alternatives may, however, have the potential to be equally problematic, as suggested recently with the use of isoeugenyl acetate to replace isoeugenol. 17 The European Union, through its Scientific Committee for Cosmetic Products and Non-Food Products intended for Consumers [SCCNFP], is actively scrutinizing propositions for mandatory labelling of all known fragrance allergens in cosmetics, if used in the product. 18 In its draft preopinion SCCNFP has concluded that consumers should be informed of the presence in a cosmetic of 24 named fragrance ingredients, but it has yet to release a position statement on natural fragrance ingredients. Improved understanding of fragrance allergy by dermatologists and, ironically, by the cosmetics industry, as well as protection for the consumer, will be best served by full qualitative disclosure of all recognized allergenic ingredients in perfumed products. The picture will never be complete if the fragrance industry holds on to important pieces of the jigsaw.