Water: Whole Effluent Toxicity
Methods for Measuring the Acute Toxicity of Effluents and Receiving Waters to Freshwater and Marine Organisms - Introduction
1.1 This manual describes acute toxicity tests for use in the National Pollutant Discharge Elimination System (NPDES) Permits Program to identify effluents and receiving waters containing toxic materials in acutely toxic concentrations. With the exception of the Holmesimysis costata Acute Test (Table 19), the methods included in this manual are referenced in Table IA, 40 CFR Part 136 regulations and, therefore, constitute approved methods for acute toxicity tests. They are also suitable for determining the toxicity of specific compounds contained in discharges. The tests may be conducted in a central laboratory or on-site, by the regulatory agency or the permittee. The Holmesimysis costata Acute Test (Table 19) is specific to Pacific Coast waters and is not listed at 40 CFR Part 136 for nationwide use. This method has been proposed but not yet approved at 40 CFR Part 136.
1.2 The data are used for NPDES permits development and to determine compliance with permit toxicity limits. Data can also be used to predict potential acute and chronic toxicity in the receiving water, based on the LC50 and appropriate dilution, application, and persistence factors. The tests are performed as a part of self-monitoring permit requirements, compliance biomonitoring inspections, toxics sampling inspections, and special investigations. Data from acute toxicity tests performed as part of permit requirements are evaluated during compliance evaluation inspections and performance audit inspections.
1.3 Modifications of these tests are also used in toxicity reduction evaluations and toxicity identification evaluations to identify the toxic components of an effluent, to aid in the development and implementation of toxicity reduction plans, and to compare and control the effectiveness of various treatment technologies for a given type of industry, irrespective of the receiving water (USEPA, 1988a; USEPA, 1988b; USEPA, 1989a; USEPA, 1989b; USEPA, 1991a).
1.4 This methods manual serves as a companion to the short-term chronic toxicity test methods manuals for freshwater and marine organisms (USEPA, 2002a; USEPA, 2002b), the NPDES compliance inspection manual (USEPA, 1988c), and the manual for evaluation of laboratories performing aquatic toxicity tests (USEPA, 1991b). In 2002, EPA revised previous editions of each of the three methods manuals (USEPA, 1993a; USEPA, 1994a; USEPA, 1994b).
1.5 Guidance for the implementation of toxicity tests in the NPDES program is provided in the Technical Support Document for Water Quality-based Toxics Control (USEPA, 1991c).
1.6 The use of any test species or test conditions other than those described in Tables 12-18 in this manual and referenced in Table 1A, 40 CFR 136.3, shall be considered a major modification to the method and subject to application and approval of alternate test procedures under 40 CFR 136.4 and 40 CFR 136.5.
1.7 These methods are restricted to use by, or under the supervision of, analysts experience in the use or conductof, and interpretation of data from, aquatic toxicity tests. Each analyst must demonstrate the ability to generate acceptable test results with the methods using the procedures described in this methods manual.
1.8 This manual was prepared in the established EMSL-Cincinnati format (USEPA, 1983a).