Identification and allergenic activity of hydroxyaldehydes - a new type of oxidation product from an ethoxylated non-ionic surfactant

Ethoxylated alcohols, which are widely used as surfactants, are susceptible to oxidation on air exposure. A complex mixture of oxidation products is formed, among which alkylated aldehydes, alkylated formates, formaldehyde and peroxides have previously been identified by our group. In the present study, we have identified a new class of oxidation product from the nonionic ethoxylated surfactant C12E5. These oxidation products are highly water-soluble hydroxyaldehydes with the general formula HO(CH2CH2O)(n)CH2CHO, n=1-4. To facilitate the identification of the hydroxyaldehydes in oxidized C12E5, reference compounds were synthesized. The sensitizing potential of 1 of the identified hydroxyaldehydes, HO(CH2CH2O)(3)CH2CHO, was studied in guinea pigs and was found to be weak. A significant cross-reactivity between this aldehyde and the next shorter homologue, HO(CH2CH2O)(2)CH2CHO, was observed. Irritant components, present in the oxidation mixture, facilitate the skin penetration of allergens, which further accentuates the importance of controlling the conditions of storage and handling of ethoxylated surfactants, to reduce the formation of allergenic and irritant oxidation products.