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Improving the laboratory accreditation process for WET methods: Progress of the NELAC’s Whole Effluent Toxicity Workgroup
Citation:
Rewa, S., R. Naddy, T. Norberg-King, P. De Lisle, G. Briggs, AND E. West. Improving the laboratory accreditation process for WET methods: Progress of the NELAC’s Whole Effluent Toxicity Workgroup. SETAC North America, Sacramento, CA, November 04 - 08, 2018.
Impact/Purpose:
Clean Water Act (CWA) implementation starts with the development of water quality criteria to protect uses, such as aquatic life.implementation of EPA’s WET test methods under the NPDES permit program completes an integrated strategy for water quality-based toxics control that fulfills the Clean Water Act’s goals to protect aquatic life and prohibit the discharge of toxic pollutants in toxic amounts. As aquatic life are exposed to innumerable chemical mixtures in the nation’s waters, whole effluent toxicity (WET) methods are used to assess whether chemical mixtures of effluents and ambient waters are causing toxicity to aquatic life, thereby filling a key role in meeting the CWA goal of “no toxics in toxic amounts.” the WET refers to the aggregate toxic effect to aquatic organisms from all pollutants contained in a facility's wastewater (effluent). These WET test methods measure the aggregate acute and short-term chronic toxicity of an effluent using standardized freshwater, marine, and estuarine plants, invertebrates, and vertebrates. EPA promulgated the WET test method guidance document in 1995 and ratified most of the methods in the EPA manuals in 2002. EPA’s WET test methods have been successfully implemented for both wastewater effluent and ambient receiving water testing. EPA has one acute testing manual and two short-term chronic WET test methods manuals for assessing not only the aggregate toxic effect of pollutants to aquatic organisms but also the aggregate effect of receiving waters to freshwater organisms.. Over the years, continued toxicity testing method modifications, increased training, and technical resources have abounded for toxicity tests while EPA’s promulgated methods have widespread use. Errata have been periodically published and a summary of the errata will be presented.In whole effluent testing, the use of the toxicity test has become a valuable component of most water quality monitoring programs, and the use of standardized acute and sublethal freshwater and marine methods specify test acceptability criteria (TAC) for survival, growth, reproduction and provide specific testing procedures. Acute toxicity of effluents appears to have decreased since WET test has been required. Data reviews of test results have shown laboratories interpret the required procedures differently. Additional interpretation guidance is needed for these technical method issues and by strengthening the knowledge exchange with practicing laboratories, more consistent interpretations should be able to be made. Additional species are needed for effluent assessments, and methods are being assessed for two sensitive species, e.g., mayflies and mussels. This presentation will discuss the progress that has been made in the conduct and application of these tests and changes made in EPAs errata, along with recommendations to improve the quality and utility these tests, including suggestions for laboratory proficiency guidelines.
Description:
Fostering the generation of environmental data of known and documented quality through an open, inclusive, and transparent process that is responsive to the needs of the community is a mission of The NELAC Institute (TNI) with the National Environmental Laboratory Accreditation Program (NELAP) (www.nelac-institute.org). TNI vision is a national accreditation program, whereby all entities involved in the generation of environmental measurement data within the United States are accredited to one uniform, rigorous, and robust program that has been implemented consistently nationwide and focuses on the technical competence of the entity pursuing accreditation. With NELAP concensus standards of best professional practices, the quality and reliability of environmental data used by federal and state agencies will be improved. Many fields of accreditation are available: metals, nutrients, oxygen demands, semi-volatile organic compounds, general chemistry I and/or II, microbiology, asbestos, synthetic organic chemicals, volatile organic compounds, radionuclides, whole effluent toxicity testing, hazardous waste characterization, petroleum hydrocarbons, perchlorate, and/or basic environmental laboratory. As such, the TNI Whole Effluent Toxicity (WET) Testing Expert Committee serves to update and maintain the whole effluent toxicity testing standard while providing technical assistance on issues related to whole effluent toxicity, develop tools to aid implementation, and to facilitate the implementation of the TNI Standard. The workgroup provides guidance for standardizing test conditions required for proficiency testing (PT)/ Discharge monitoring reporting quality assurance (DMRQA) studies performed under the auspices of the USEPA, rather than the current practice of conducting multiple tests using different NPDES permit test conditions, so that a statistically significant number of comparable sample results are available. Another recommendation was to improve the statistical power and evaluation of WET data sets and results in PT/DMRQA studies by selecting one statistical method to calculate the test endpoint and eliminating the use of hypothesis test endpoints. With experts, the programs for TNI on WET testing methods, quality control and data interpretation is updated. In this presentation, we will highlight some of the solutions to these issues as recommended by TNI WET workgroup. This abstract does not necessarily represent the position or policy of the U.S. EPA.