Are alkyl glucosides really allergens?

Abstract

To the Editor: The request emanating from a certain number of personal hygiene product consumers, particularly those using shampoos, to have foaming products without alkyl sulfates at their disposal has driven the cosmetics industry to turn to alternatives, such as alkyl glucosides. These are obtained by condensing fatty alcohols and glucose. They are nonionic surfactants, considered to be safe for use in cosmetics, and less likely to cause irritation compared with anionic surfactants, such as sodium lauryl sulfate.1Gijbels D. Timmermans A. Serrano P. Verreycken E. Goossens A. Allergic contact dermatitis caused by alkyl glucosides.Contact Dermatitis. 2014; 70: 175-182Crossref PubMed Scopus (36) Google Scholar Apart from this quality, they have the advantage of being biodegradable. Consequently, their use has increased over the past 20 years, and they are currently present in numerous rinsed products, such as shampoos, and they can also be found in nonrinsed products, such as sun care products. Indeed, a raw material such as methylene bis-benzotriazolyl tetramethylbutylphenol is combined with decyl glucoside in the speciality named Tinosorb M (BASF Corporation, Florham Park, NJ). At first glance, alkyl glucosides were not thought to have a sensitizing potential, and yet, a sufficiently high number of cases of contact allergies have been published, to the extent that they were collectively branded 2017 “allergen of the year.”2Boozalis E. Patel S. “Allergen of the year” alkyl glucoside is an ingredient in top-selling sunscreens and facial moisturizers.J Am Acad Dermatol. 2018; 78: 809-810Abstract Full Text Full Text PDF PubMed Scopus (12) Google Scholar The fact that they are more and more frequently found in cosmetics has led to an increased number of cases of allergies related to their use. It can be noted that the molecules that are most frequently involved are lauryl- and decyl glucosides. Signs occur principally in persons with atopic diseases. The sensitization mechanism is not yet known. The situation concerning alkyl glucosides is somewhat reminiscent of one concerning cocamido propylbetaine, an amphoteric surfactant, used in the formulation of gentle shampoos. This chemical was suspected of being allergenic, and after a certain number of years, it was realized that the real allergen was 3-dimethylaminopropylamine, an aliphatic amine used to synthesize it. The purification of the raw material enabled this useful ingredient to be restored to use.3Pigatto P. Bigardi A. Cusano F. Contact dermatitis to cocamidopropylbetaine is caused by residual amines: relevance, clinical characteristics, and review of the literature.Am J Contact Dermatitis. 1995; 6: 13-16Crossref Scopus (43) Google Scholar In the case of alkyl glucosides, it must be known that the production of the raw material can be done in different ways, in particularly through biotechnology. With this method, quite expensive enzymes requiring an immobilization stage are used. This method involves rendering the enzymatic system insoluble in the reaction medium, which then enables it to be collected. Immobilization can be done in different ways and, in particular, via reticulation using glutaraldehyde,4Katchalski-Katzir E. Kraemer D. Eupergit® C, a carrier for immobilization of enzymes of industrial potential.J Mol Catal B Enzym. 2000; 10: 157-176Crossref Scopus (381) Google Scholar which is known for its antimicrobial properties and is a formaldehyde releaser, which has sensitizing properties.5van Triel J. van Bree W. Roberts D. Muijser H. Kuper F. The respiratory allergen glutaraldehyde in the local lymph node assay: sensitization by skin exposure, but not by inhalation.Toxicology. 2011; 279: 115-122Crossref PubMed Scopus (11) Google Scholar This is perhaps the true culprit.