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allergens
Allergens are substances capable of producing hypersensitivity reactions, involving the immune system. Most often, they are proteins or protein compounds.
Contact allergy results from a specific acquired hypersensitivity reaction, also known as cell-mediated hypersensitivity (type IV allergy according to Coombs and Gell). For sensitisation (acquiring an allergy) individuals must have significant and usually repeated contact with the allergen. Therefore individuals may be exposed to allergens for years before finally developing hypersensitivity. Numerous allergens have been identified as causes for allergic contact dermatitis. The most common contact allergens are nickel and fragrance mix.
Important contact allergens in Germany in the year 2000 (IVDK = Informations-verbund Dermatologischer Kliniken):
Allergens
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Positive reactions (%)
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Appearance
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Nickel sulfate
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17.6
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jewellery, cutlery, zipper, wristwatch
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Fragrance mix
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10.2
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cosmetics, perfume, cleaning agents
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Balsam of Peru
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8.4
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scent of cosmetics, topical medicaments, tobacco
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Thimerosal
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7.3
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preservative in vaccines, eye drops
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Cobalt
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5.3
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jewellery, cutlery, zipper, wristwatch, cement, hair tinting lotion
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Lanolin
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4.3
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creams, ointments, printing ink,
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Colophony
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4.2
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paper, band-aid, adhesives, polish, cosmetics
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Para-phenylendiamine
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4.0
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hair tinting lotion, paints
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MDBGN/PE
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3.8
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preservative in cosmetics, pharmaceuticals
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Potassium dichromate
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3.4
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cement, leather, impregnation, galvanisation
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Thiuram mix
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2.4
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any kind of vulcanised rubber
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Formaldehyde
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1.8
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desinfectant, plastics
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Several ingredients in cosmetics may also cause allergic reactions. Important contact allergens in skin care and skin cleansing products are listed below:
Fragrances/ vegetable ingredients
panthenol
propolis
colophony
balsam of Peru
camomile
tea-tree oil
Preserving agents
chlormethylisothiazolinone (Kathon CG, Euxyl K 100)
formaldehyde
quaternum 15 (Dowicill 200)
imidazolidinyl urea (Germall 115)
bronopol
Euxyl K 400
parabenes
Antioxidants
butylhydroxyanisol
butylhydroxytoluol
Ointment bases
lanolin alcohol
amerchol
propylene glycol
polyethylene glycol
Emulsifying agents
cetyl alcohol
cetylstearyl alcohol
glyceryl stearate
sodium lauryl sulfate
cocamidopropylbetaine
For the following 26 fragrances, the European Union has defined a duty of declaration. They are labeled according to the International Nomenclature of Cosmetic Ingredients (INCI). The fragrances in bold letters are included in the fragrance-mix (mixture of several fragrances used in allergological testing of type IV-allergies).
INCI-Labeling
Amyl Cinnamal
Benzyl Alcohol
Cinnamyl Alcohol
Citral
Eugenol
Hydroxycitronellal
Isoeugenol
Amcylcinnamyl Alcohol
Benzyl Salicylate
Cinnamal
Coumarin
Geraniol
Hydroxyisohexyl-3-Cyclohexene
Carboxaldehyd
Anise Alcohol
Benzyl Cinnamate
Farnesol
Butylphenyl Methylpropional
Linalool
Benzyl Benzoate
Citronellol
Hexyl Cinnamal
d-Limonene
Methyl-2-Octynoate
Alpha-Isomethyl Ionone
Evernia Prunastri Extract
Evernia Furfuracea Extract
(Vera Mahler: Entwicklung und Trends der Kontaktallergene. In: Plewig G, Kaudewitz P, Sander CA. Fortschritte der praktischen Dermatologie und Venerologie 2004. Springer-Verlag Berlin Heidelberg 2005)
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