Aqatic toxicity equivalency factors for chlorinated phenolic compounds present in pulp mill effluents

Abstract

Aquatic toxicity equivalency factors (TEFs) for chlorinated phenolic compounds present in blached kraft mill effluents were estimated using published chronic toxicity data for fathead minnows, rainbow trout, zebra fish, American flagfish, and sea urchins. To provide the most consistent and reliable approach for estimating relative toxicity, each set of toxicity data employed for TEF determination encompassed only data relating to a common toxic end point, a single aquatic test species, and a common method of testing and of statistical analysis. The TEF values were determined as a ratio of the chronic threshold values for the mono-to pentachloro-substituted phenolics to that for pentachlorophenol, where the threshold values were obtained from linear regression equations relating chronic toxicity to the number of chlorine substituents for a given chlorinated phenolic. Using this approach, the TEF values for monochloro-, dichloro-, trichloro-, tetrachloro-, and pentachloro-substituted phenolic compounds were determined to be 0.04, 0.1, 0.2, 0.5, and 1.0, respectively.