Toxicity Identification Evaluation: Characterization of Chronically Toxic Effluents, Phase

This manual is intended to provide guidance to aid dischargers in characterizing the type of toxicants that are causing chronic toxicity in industrial and municipal effluents. In a regulatory context, a toxicity identification evaluation (TIE) may be required as part of the National Pollutant Discharge Elimination System (NPDES) permit or as an enforcement action. TIES may also be conducted by permittees on a volunteer basis to characterize their discharge toxicity. The Phase I chronic toxicity methods are modified from those described in the acute Phase I TIE manual (EPA, 1988A; EPA, 1991A) and additional techniques are incorporated. This chronic Phase I manual describes procedures for characterizing the physicaV chemical nature of toxicants in effluents that exhibit chronic toxicity to freshwater species, although many of the principles and procedures are similar for TIES on marine species. Aliquots of effluent samples are manipulated and the resulting effect on toxicity measured. The objective is to characterize the toxicants so that appropriate analytical methods can be chosen to identify the toxicants. The general approach to the chronic toxicity characterization is a two tiered approach, where usually Tier 1 is applied before proceeding to Tier 2. Tier 1 consists of filtration, aeration, use of additives to chelate or reduce the toxicants, minor pH adjustments, and use of a separation technique with the C, solid phase extraction (SPE) resin. Each effluent is characterized in Tier 1 by performing the manipulations at the initial pH (pH i) of the effluent. Tier 2 consists of the Tier 1 manipulations combined with pH adjustments of additional aliquots of the effluent sample, and the Tier 2 characterization steps include aeration, filtration, and the C,, solid phase extraction of effluent samples adjusted to pH 3 and pH 10. The Phase I characterization methods were developed for the short-term “chronic” test methods using two species, Ceriodaphnia dubia and the fathead minnow (Pimephales promelas) (EPA, 1989C). Chronic threshold levels for the various additives (sodium thiosulfate, EDTA, methanol) used in some of the characterization tests are provided for these species. Although developed for these species, the characterization techniques should be applicable to other species as well, provided threshold levels are established. The guidance provided in this manual is intended to be supplemental to that given in the acute Phase I manual (EPA, 1991A). Sections of this chronic Phase I TIE manual discuss quality assurance, effluent handling, facilities and equipment, health and safety, dilution water, principles of the chronic TIE testing, and the Phase I characterization tests as a two tiered approach. The use of the whole effluent test as a baseline test (in manner similar to the acute Phase I characterization procedure), the appropriate treatment of dilution water for blanks and the toxic levels of the additives for two species are described. Use of short-cuts, reduced test volumes, reduced test duration, and a small number of replicates are discussed. The importance of sample type, frequency of sample collection and renewal, and descriptions of all manipulations are discussed, along with a section on the application of combining several of the characterization tests.