EXPERIMENTAL DETERMINATION OF BIOCONCENTRATION OF THE NONIONIC SURFACTANT ALCOHOL ETHOXYLATE

Abstract

Acohol ethoxylate (AE) is the most widely usednonionic surfactant in householddetergents. Herewe present compound-specific bioconcentration data for AE constituents determined in flow-through experiments. Values of the bioconcentration factor (BCF) and the rate constants of uptake (k1) and elimination (k2) in fathead minnows (Pimephales promelas) ranged between <5 and 390 L/kg, 330 and 1,660 L/kg/d, and 3.3 and 59/d, respectively. The high values of k2 suggested rapid biotransformation of AE. As a consequence, AE was not stored inside the fish, and no relationship between the BCF and the lipid content was observed. The influence of both the alkyl and the ethoxylate chain length was studied. The BCF as well as k1 increased with increasing length of the alkyl chain and decreasing length of the ethoxylate chain. In contrast, a decrease of k2 with increasing alkyl chain length and decreasing ethoxylate chain length was found. Using structure–bioconcentration relationships, the bioconcentration potential of an AE mixture was estimated to be 140 L/kg. The bioconcentration potential of AE seemed to be largely unaffected by processes occurring during wastewater treatment.