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AN ASSESSMENT OF PHTHALATE ESTER TOXICITY TO FRESHWATER BENTHOS: 2. SEDIMENT EXPOSURES
Citation:
Call, D. J., D. A. Cox, D. L. Geiger, K. I. Genisot, T. P. Markee, L. T. Brooke, C. N. Polkinghorne, F. VandeVenter, K. A. Robillard, J. W. Gorsuch, T. F. Parkerton, G T. Ankley, AND D R. Mount. AN ASSESSMENT OF PHTHALATE ESTER TOXICITY TO FRESHWATER BENTHOS: 2. SEDIMENT EXPOSURES. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY. SETAC Press, Pensacola, FL, 20(8):1805-1815, (2001).
Description:
Seven phthalate esters were evaluated for their stability and 10-d acute toxicity to the freshwater invertebrates Hyalella azteca and Chironomus tentans following incorporation into sediment. The chemicals were diethyl (DEP), di-n-butyl (DBP), di-n-hyxyl (DHP), di-[2-ethylhexyl] (DEHP), diisononyl1 (DINP), diisodecyl (DIDP) phthalate, and a mixture of C7, C9 and C11 esters (D711P). One of the phthalate esters, DBP, was tested in three sediments of varying organic carbon content (2.45 to 14.1 percent) to evaluate the role of organic carbon in determining bioavailability. Spiking concentrations for each phthalate ester were determined based on the results of water-only toxicity tests (Call et al. 1999; see accompanying paper), sediment organic carbon analyses and preliminary spiking studies that assessed compound stability in sediment. The rapid loss of DEP precluded the performance of a toxicity test with H. azteca. DHP, DEHP, DINP, DIDP and D711P did not affect either survival or dry weight of C. tentans or H. azteca in 10-d exposures to measured concentrations of phthalates in sediment between2,090 and 3,170 mg/kg. These findings are consistent with predictions based on equilibrium partitioning (EqP) theory and toxicity data from the aqueous exposures. Pore water 10-d LC50 values for C. tentans based upon measured DBP concentrations in the three test sediments were 1.6 to 3.9 times greater than the LC50 value from an aquueous exposure. Correction for potential binding of the phthalate to dissolved organic carbon (DOC) improved the level of agreement with the aqueous LC50. Normalization of DBP concentrations for total organic carbon (TOC) content resulted in LC50 values for C. tentans of 33,700, 34,700 and 33,500 mg/kg organic carbon for the low, medium and high TOC sediments, respectively. The toxicity of DEP to C. tentans, and of DBP to H. azteca were less than predicted by EqP theory. This may have been due to behavioral factors ...