Ethoxylated surfactant compounds are a broad class of non-ionic surfactants that include alkylphenol ethoxylates (APEOs) and alcohol ethoxylates (AEs). Together, APEOs and AEs are used in a wide range of consumer and industrial applications as emulsifiers, wetting agents, dispersing agents, stabilizers, antioxidants, curing agents, and surface tension agents. Commonly used products that may contain APEOs and AEs include detergents, degreasers, fuel and lubricant fuel additives, paints, pesticide formulations, textiles, personal care products, adhesives, varnishes, plastic polymers, phenolic resins, concrete, tire rubber, and fire-fighting foam suppressant. Nonylphenol ethoxylates (NPEOs), a major subclass within APEOs, have received scientific and regulatory attention because they may impact aquatic ecosystems, which are particularly sensitive to NPEO degradation products including nonylphenol (NP).

The Regional Monitoring Program for Water Quality in San Francisco Bay (RMP) funded a multi-year study to investigate the presence of a broad suite of ethoxylated surfactants in Bay water, urban stormwater runoff, and municipal wastewater effluent. Previous monitoring of ethoxylated surfactants in San Francisco Bay had been limited to a very small subset of ethoxylated surfactants - short-chain (mono- and diethoxylate) NPEOs and nonylphenol (NP) - in samples collected in 2010. The goals of the present study were to provide updated monitoring information to evaluate the placement of this class within the RMP’s tiered risk-based framework and to guide appropriate future monitoring and management strategies.