In Europe, a cosmetic is defined as any substance or preparation intended to be placed in contact with the various external parts of the human body (epidermis, hair system, nails, lips and external genital organs) or with the teeth and the mucous membranes of the oral cavity with a view exclusively or mainly to cleaning them, perfuming them, changing their appearance and/or correcting body odours and/or protecting them or keeping them in good condition. Although the definition may change slightly in other countries, what is obvious from this definition is that cosmetic products are part of everyday life for all of us. Consequently, regulations generally require that cosmetic products must not cause damage to human health when applied under normal or reasonably foreseeable conditions of use. The responsibility for ensuring consumer safety rests with the manufacturer that places the product on the market.
It is our view that manufacturers generally discharge this responsibility successfully, with cosmetic products around the world being regarded as safe.
However, there is one important exception: cosmetic products do appear to be one of the more important causes of allergic contact dermatitis (ACD). We are aware that the process associated with the identification, characterisation and safety assessment of the substances which can cause ACD, is currently the subject of high-level review, particularly with respect to fragrance allergy. Furthermore, this review is taking place at a time when the world of toxicology is progressing from the old in vivo methods to embrace the brave new world of in vitro assays. Nowhere is this more relevant than in the field of skin sensitisers, contact allergy and ACD. Against this background, it could not be more timely to have this Special Issue of the journal Cosmetics. The Special Issue “Cosmetic Contact Allergens” is a collection of several authoritative papers that draws upon the collective expertise of undisputed leaders in the fields of contact hypersensitivity, immunity, immunotoxicology, and in vitro and in silico methods. What is exciting is that this represents a unique opportunity to implement in vitro methods, apply new risk assessment techniques and then receive feedback from dermatology clinics and the consumer market. What is challenging is to ensure that this is done well, is done comprehensively, such that the feedback demonstrates that the problem of ACD to cosmetics has been reduced to an acceptably low level.
The Special Issue explores the clinical relevance of cosmetic allergens, including hair dyes and preservatives, the immunological and biological mechanisms underlying chemical allergen-induced contact allergy, the toxicology and the opportunity to identify their allergenic potentials based on non-animal testing, with the ultimate aim of making contact allergy to cosmetics history.