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PROCEDURES FOR THE DERIVATION OF EQUILIBRIUM PARTITIONING SEDIMENT BENCHMARKS (ESBS) FOR THE PROTECTION OF BENTHIC ORGANISMS: COMPENDIUM OF TIER 2 VALUES FOR NONIONIC ORGANICS
Citation:
Burgess, R M., W. J. BERRY, D. R. MOUNT, G. T. ANKLEY, S. IRELAND, D. M. DI TORO, D. J. HANSEN, J. A. McGrath, L. D. DeRosa, H. BELL, F. James KEATING, M. C. REILEY, AND C. S. ZARBA. PROCEDURES FOR THE DERIVATION OF EQUILIBRIUM PARTITIONING SEDIMENT BENCHMARKS (ESBS) FOR THE PROTECTION OF BENTHIC ORGANISMS: COMPENDIUM OF TIER 2 VALUES FOR NONIONIC ORGANICS. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-02/016 (NTIS PB2008-107282), 2008.
Impact/Purpose:
The equilibrium partitioning sediment benchmark (ESB) document prepared by scientists at the Atlantic Ecology Division and Mid-Continent Ecology Division describes procedures to determine what amounts of 32 nonionic organic chemicals in sediment are considered non-toxic or safe to benthic organisms such as worms, clams and shrimp. The equilibrium partitioning (EqP) approach was chosen because it is based on the concentrations of chemical(s) that are known to be harmful and bioavailable in the environment. This document, and four others published over the last five years and one more to be released in the next few years, will be useful for the program offices, including Superfund, and Regions in conducting contami¬nated sediment assessments. The documents represent approximately 15 years of research and development by scientists working within EPAs Office of Research and Development (ORD), as well as the Office of Water, and review of the scientific approach by the Agencys Science Advisory Board (SAB). Originally, this document was to be published by the Office of Water as a formal sediment quality criterion (SQC), but the decision was made approximately seven years ago for ORD to publish this and the other ESBs as technical information. Consequently, the document is being published purely to aid in conducting sediment assessments.
Description:
This equilibrium partitioning sediment benchmark (ESB) document describes procedures to derive concentrations for 32 nonionic organic chemicals in sediment which are protective of the presence of freshwater and marine benthic organisms. The equilibrium partitioning (EqP) approach was chosen because it accounts for the varying biological availability of chemicals in different sediments and allows for the incorporation of the appropriate biological effects concentration. This provides for the derivation of benchmarks that are causally linked to the specific chemical, applicable across sediments, and appropriately protective of benthic organisms. EqP can be used to calculate ESBs for any toxicity endpoint for which there are water-only toxicity data; it is not limited to any single effect endpoint. For the purposes of this document, ESBs for 32 nonionic organic chemicals, including several low molecular weight aliphatic and aromatic compounds, pesticides, and phthalates, were derived using Final Chronic Values (FCV) from Water Quality Criteria (WQC) or Secondary Chronic Values (SCV) derived from existing toxicological data using the Great Lakes Water Quality Initiative (GLI) or narcosis theory approaches. These values are intended to be the concentration of each chemical in water that is protective of the presence of aquatic life. For nonionic organic chemicals demonstrating a narcotic mode of action, ESBs derived using the GLI approach specifically for freshwater organisms were assumed to also be protective of marine organisms. This assumption is based on the similar sensitivity of freshwater and marine organisms to narcotic chemicals like some of the nonionic organics in this document. For this reason, SCVs derived using narcosis theory are protective of both freshwater and marine organisms. For chemicals with more specific modes of action, freshwater and marine organisms were not assumed to be similar in sensitivity, and separate freshwater and marine ESBs were derived as the available data allowed. Because of the lack of a comprehensive toxicity data set and other reasons discussed in this document in detail, values derived here are considered Tier 2 ESBs (ESBTier2). The presentation of these ESBs is such that updated values could be calculated as new toxicity data become available. The ESBTier2 is derived by multiplying the FCV or SCV by a chemical’s KOC, yielding the concentration in sediment that should provide the same level of protection that the FCV or SCV provides in water. The ESBTier2 should be interpreted as a chemical concentration below which adverse effects are not expected. At concentrations above the ESBTier2, and assuming equilibrium between phases, effects may occur with increasing severity as the degree of exceedance increases. The document also includes examples demonstrating the calculation of conventionally-derived and narcosis-based ESBs that discuss an approach for addressing mixtures of narcotic chemicals. ESB documents have also been developed for two pesticides (endrin, dieldrin), polycyclic aromatic hydrocarbon (PAH) mixtures, and metal mixtures. The ESBs do not intrinsically consider the antagonistic, additive or synergistic effects of other sediment contaminants in combination with the individual nonionic organic chemicals discussed in this document or the potential for bioaccumulation and trophic transfer of these chemicals to aquatic life, wildlife or humans. However, for narcotic chemicals, an approach for considering the toxicity of mixtures is presented. Important assumptions and considerations for applying and interpreting the ESBs are also discussed.
URLs/Downloads:
Procedures for the Derivation of Equilibrium Partitioning Sediment Benchmarks (ESBs) for the Protection of Benthic Organisms: Compendium of Teir 2 Values for Nonionic Organics (PDF, NA pp, 1117 KB, about PDF)REVIEW #1.PDF (PDF, NA pp, 27 KB, about PDF)
Reconciliation Memo (PDF, NA pp, 371 KB, about PDF)
Reconciliation Memo (PDF, NA pp, 371 KB, about PDF)
Peer Review Plan (PDF, NA pp, 35 KB, about PDF)
Charge (PDF, NA pp, 20 KB, about PDF)