Allergenic oxidation products in ethoxylated non-ionic surfactants : Chemical characterization and studies on allergenic activity

Sammanfattning: The susceptibility of ethoxylated non-ionic surfactants to oxidation on exposure to air was investigated. Surfactants have a complex chemical composition and are widely used in a variety of applications for to their amphiphilic properties. Ethoxylated non-ionic surfactants are regarded by the producers to be stable at normal handling. However, ethoxylated surfactants are polyethers and as such susceptible to oxidation on exposure to air, which is theoretically discussed in literature. Hand eczema is a common occupational disease of which mom than half of the cases is considered to be caused by work with surfactants and water. Surfactants are known to cause skin irritation, but cases of allergic contact dermatitis have also been reported.Some ethoxylated surfactants were handled at room temperature in a manner that imitated ordinary handling at work. All samples autoxidized and the structures of some of the components formed were identified with liquid chromatography (HPLC) and gas chromatography (GC). Structural analogues were synthesized and could be identified in the complex oxidation mixture using nuclear magnetic resonance, infrared and mass spectroscopy (NMR, FT-IR, MS). The allergenic potential of the identified oxidationproducts was studied in experimental sensitization studies in guinea pigs. The physicochemical behavior of individual oxidation products in pure water solutions was investigated.A well-known contact allergen, i.e. formaldehyde, and previously undescribed allergenic compounds were identified after air exposure of the ethoxylated surfactants. At oxidation, the content of free formaldehyde increased above the level for warning labelling within the European Union. The allergenic potential of one of the main compounds identified, an ethoxylated aldehyde, was of similar magnitude as that of formaldehyde. The oxidation led to a gradual change in the physicochemical properties.The observed autoxidation of commonly used ethoxylated surfactants and formation of a complex degradation mixture indicate a potential health risk that has not been considered before. Previously unknown breakdown/oxidation products were identified, some of which had allergenic properties. This oxidation can also affect the technical performance of the surfactants. The observed allergenic properties of the formed oxidation products may be of importance in occupational exposure to polyoxyethylene surfactants.