Quality Standards for Nonylphenol and Octylphenol in sediment based on ecotoxicological studies

Nonylphenol (NP) and octylphenol (OP) are degradation products of alkylphenolethoxylates (APE), non-ionic surfactants employed for more than 40 years, which elicit endocrine disrupting effects on aquatic organisms. For this reason, since 2001, they have been included in the list of priority hazardous substances of the Water Framework Directive. Quality standards (QS) for different environmental compartments were set out, and NP, OP and APE have been subject to EU restrictive regulation on marketing and use since 2003. The significant decrease in NP and OP concentrations in water in the last years demonstrates the effectiveness of the control measures that the European Union put in place to control these priority hazardous substances. However NP and OP concentrations in monitored sediments are often above QS for sediments raising doubts about the reliability of these QSs. In the framework of a European initiative for the harmonization and derivation of Environmental Quality Standards, Italy and Denmark collaborated to derive a robust and reliable QSsed for these two priority substances. Toxicological tests with Chironomus riparius, Lumbriculus variegatus and Hyalella Azteca were carried out according to OECD and USEPA guidelines for both NP and OP. The test results and literature data were combined and a QSsed for NP and for OP based on ecotoxicological studies was derived according to the Technical Guidance Document on deriving EQS (CIS-WFD Guidance n. 27). The estimated QSs for sediment, normalised to organic carbon content, were 37 and 25 mg/kg OC respectively for OP and for NP. These QSs for sediment, based on ecotoxicological studies, are about 100 higher the previously derived QSs which were calculated by Equilibrium Partition (EqP) approach.