Article written: October 2001
Fragrances are among the most common causes of allergic contact dermatitis, and they are certainly the most common cosmetic ingredient causing allergic contact dermatitis. They can also cause photodermatitis, contact urticaria, irritation, hyperpigmentation and depigmentation of skin. Fragrances have widespread use and are found in:
- Hair products
- Skin care products
- Laundry products
- Dentifrices (toothpastes), Mouth Wash
- Cleaning products / Detergents
- Pharmaceutical creams & suppositories
- Food Flavours such as ice cream, chewing gum, bakery products, soft drinks, and sweets.
Usually the source of the fragrance exposure is a skin or hair care product rather than cologne or perfumes itself.
Fragrance raw materials can be of organic origin, derived from animal or plant sources, or from synthetic chemical source.
More than 5000 fragrance materials are in use today. A typical complete perfume may consist of 10 to 300 separate components.
The maximum concentration of fragrances in various products is as follows:
- Masking perfumes, 0.1% or less
- Cosmetics, 0.5%
- Colognes, 4%
- Toilet water, 5%
- Perfume, 20%
Commercial perfumes are mixtures of essential oils and synthetic compounds, with at least 20 ingredients as a rule. The mixture of volatile substances determines the scent. To delay evaporation, "fixatives" are added. Common "fixatives" are balsams, benzoyl benzoate, benzyl salicylate and synthetic musks. Sensitivity to musks has been reported and sensitivity to balsams is common.
Screening for Fragrance Allergy
- Balsam of Peru
- Fragrance Mix:
- Oak Moss
- Cinnamic aldehyde
- Cinnamic alcohol
- Alpha amyl cinnamic alcohol
- Isoeugenol & Eugenol
- Musk Ambrette and Moskene.
Balsam of Peru
Balsam of Peru (BP) is usually included in the standard screening patch-test series as an indicator of fragrance sensitivity. It is positive in 50% of cases of fragrance allergy. BP is a naturally occurring substance, obtained from fir trees. It is composed of many allergens including benzyl acetate, benzoyl alcohol, cinnamic acid, cinnamic alcohol, cinnamic aldehyde, eugenol, and isoeugenol.
This is also used to screen for fragrance allergy. Typically it is a mixture of the 8 individual fragrances listed above.
Testing with BP and Fragrance Mix will probably detect about 75% of the cases of fragrance allergy.
Cinnamic Alcohol & Cinnamic Aldehyde
These 2 commonly used fragrances are well known allergens. Along with other chemically related compounds, they are used as flavouring agents, as well as fragrances. They are used in:
- Beverages (cola), Vermouths, bitters
- Chewing gums
- Toothpaste & mouth wash
- Toilet soaps
Hydroxycitronellal is a synthetic fragrance used widely in floralizing perfume materials. It is also used in insecticides and antiseptics.
Isoeugenol & Eugenol
Eugenol is a component of essential oils obtained from spices including cloves and cinnamon leaf, with an odour and taste of cloves. It is also present in pimento, calamus, cananga, camphor, sassafras, and nutmeg. In addition a number of flowers contain eugenol, including roses, carnations, hyacinths, and violets. It is found in Balsam of Peru and in the Fragrance mix. It has been used for a long time as a spice in the food industry and is approved by the FDA as a flavouring agent for ingestion. It has been used to preserve meats and other foods and has inherent insecticidal and fungicidal properties. Its usual concentration varies from 0.03% in creams and lotions to 0.4% in perfumes. Eugenol "quenches" non-immune contact urticarial reactions but has no effect on delayed-type hypersensitivity reactions to cinnamic aldehyde.
- Cosmetics (clove and carnation scent)
- Mouthwashes, toothpaste
- Dental cements and packing agents
- Food flavour
- Over-the counter medicines
Isoeugenol is manufactured by the isomerization of eugenol. It has a spicy clove-like odour. Isoeugenol and Eugenol may cross-react.
The North American Contact Dermatitis Group found 3.1% of their patients who were tested to the fragrance tray to be allergic to isoeugenol. Because of its sensitizing capacity, it has been recommended that isoeugenol be used at no more than 1% concentration in fragrance compounds.
Geraniol is the alcoholic extract obtained from geranium oil. It has a pleasant, sweet rose-like odour. Most geraniol on the market at present is synthetic. Geraniol is one of the most widely used terpenoid fragrance chemicals in soaps, detergents, and cosmetics. It is also a component of natural flavours and essential oils used in flavour compounds. It is found in over 250 essential oils and accounts for over 90% of palmarosa oil and a large portion of geranium and rose oils. The fragrance mix has geraniol as one of its component.
Oak Moss Absolute
Oak Moss Absolute is a natural product derived from tree lichen. An essential oil is produced by solvent extraction of the plant. The part of the essential oil that is alcohol extractable is called absolute or isolate. It is a commonly used fragrance material in aftershave lotions to give them an earthy, woody, and "masculine" odour. Oak moss absolute is a component of the fragrance mix used in patch testing.
The prevalence of oak moss allergy reported by different investigators varied from 1% to 12%, depending on the concentration used for patch testing and other variables. Sensitivity to oak moss was found to be more common in whites than in Asians in a study conducted concomitantly in Europe, Japan, and the USA.
Benzyl Alcohol is a fragrance ingredient that is also used as an antiseptic topically and as a preservative in injectible medications.
Some Topical Products containing Benzyl Alcohol:
- Aristocort A Cream
- Lotrimin Lotion
Injectable Medications Containing Benzyl Alcohol:
- Intron A.
Musk Ambrette & Musk Moskene
Musk Ambrette is a synthetic chemical that has been used widely for the last 60 years. It is used in fragrances, soaps, detergents, creams, lotions, and dentifrices. Musk ambrette is a photosensitising fragrance. It can also cause an airborne allergic contact dermatitis of the face with hyperpigmentation. There was a reported case due to chronic burning of incense for several years.
Musk Moskene is related to Musk ambrette, but it causes less allergic contact dermatitis and photodermatitis.
Flavouring agents & spices
Contact sensitivity to spices occurs mainly from occupational exposure, but sensitivity to mustard, cinnamon, vanilla, allspice, oil of juniper and cloves is not uncommon, even among consumers. Cigarette & pipe tobaccos contain about 1% of spices and perfumes. The clinical consequence is unknown.
In modern food industry a large number of synthetic flavouring agents are used.
Strategies implemented to reduce the sensitising potential of fragrance materials:
- Elimination of known sensitizers
- Use of safe alternatives
- Use of pure, standardised fragrance materials
- Formulation of products that contain ingredients which may inhibit sensitisation ("quenching" agents). For example, cinnamic aldehyde, which is a strong sensitizer, when formulated with an equal weight of eugenol (quencher), prevents sensitisation.
International Fragrance association (IFRA) industry guidelines to restrict ingredient usage*
Selected Fragrance Code of Practise
*Extracted from the International Fragrance Association (IFRA) Code of Practise
Diagnosis of Fragrance Allergy
Patch Test to Balsam of Peru and Fragrance Mix is a good screen to start with.
Since most individual fragrances are not listed on most cosmetics labels, a Use Test (applying the new product to a clear part of the forearm twice daily for 5 days & observe for dermatitis) should be performed before starting a new perfumed product. This is also advisable in cases of cosmetic products labelled "unscented" as some still may contain a certain amount of fragrances (0.01%).