Toxicity of Hexachlorobenzene to Hyalella Azteca and Chironomus Tentans in Spiked Sediment Bioassays

The present study assesses the sediment toxicity levels of three Spanish estuaries, as well as the suitability of two microorganisms, the benthic microalga Cylindrotheca closterium and the harpacticoid copepod Tisbe battagliai, as test organisms in whole-sediment toxicity assays. The sensitivity of both species to potentially polluted sediments was compared. Three sites at the southwest of the Iberian Peninsula were chosen: the Ría of Huelva, the Guadalquivir Estuary, and the Bay of Algeciras. Inhibition data were based on growth for C. closterium and fecundity for T. battagliai. No toxicity was recorded for the microalga in the Guadalquivir Estuary and the Bay of Algeciras. However, for T. battagliai, inhibition of fecundity was approximately 50% in those zones, indicating higher sensitivity. Samples from stations in the Ría of Huelva were the most toxic of all those assayed; inhibition values higher than 90% were obtained for both organisms. The highest values for total metal concentrations such as arsenic (As), cadmium (Cd), copper (Cu), iron (Fe), lead (Pb), tin (Sn), and zinc (Zn) were found in the Ría of Huelva, which can be classified as severely impacted. The Guadalquivir Estuary and the Bay of Algeciras can be considered moderately impacted. In general, both methodologies are suitable for application in ecotoxicological studies.

Section: Resultsmentioning

confidence: 90%

Ranking sediment samples from three Spanish estuaries in relation to its toxicity for two benthic species: The microalga Cylindrotheca closterium and the copepod Tisbe battagliai

Araújo

Diz

Tornero

et al. 2009

“…Predicted effects thresholds were calculated for chlorobenzene, dichlorobenzenes, trichlorobenzenes, tetrachlorobenzenes, and penta‐chlorobenzene, but not for hexachlorobenzene. Previous research has demonstrated that hexachlorobenzene is unlikely to be a primary stressor in sediment [13, 14], because its low solubility relative to its toxicity apparently precludes direct toxic effects on aquatic organisms.…”

Section: Total Chlorinated Benzenes Modelmentioning

confidence: 99%

“…Predicted effects thresholds were calculated for chlorobenzene, dichlorobenzenes, trichlorobenzenes, tetrachlorobenzenes, and penta- chlorobenzene, but not for hexachlorobenzene. Previous research has demonstrated that hexachlorobenzene is unlikely to be a primary stressor in sediment [13,14], because its low solubility relative to its toxicity apparently precludes direct toxic effects on aquatic organisms. In addition to justifying the grouping of chlorinated benzene congeners by degree of chlorination, the QSAR approach could be incorporated in a probabilistic model by defining the relationship between PETs for different congeners based on published QSAR results.…”

Section: Interpretation Of Qsar Studiesmentioning

confidence: 99%

A model to predict threshold concentrations for toxic effects of chlorinated benzenes in sediment

Fuchsman

Duda

Barber

1999

Self Cite

Abstract-A probabilistic model was developed to predict effects threshold concentrations for chlorinated benzenes in sediment. Based on published quantitative structure-activity relationships relating the toxicity of chlorinated benzenes to the degree of chlorination, congeners with the same number of chlorine substitutions were considered toxicologically equivalent. Hexachlorobenzene was excluded from the assessment based on a lack of aquatic toxicity at the water solubility limit. The equilibrium partitioning approach was applied in a probabilistic analysis to derive predicted effects thresholds (PETs) for each chlorinated benzene group, with model input distributions defined by published log K ow values and aquatic toxicity data (LC50s and acute to chronic ratios) extracted from the published literature. The probabilistic distributions of PETs generally increased with chlorination, with 20th percentile values ranging from 3.2 mg/kg 1%OC for chlorobenzene to 67 mg/kg 1%OC for tetrachlorobenzene congeners. The toxicity of total chlorinated benzenes in sediment can be assessed by applying the PETs in a toxic index model, based on the assumption that multiple chlorinated benzene congeners will show approximately additive toxicity, as characteristic of nonpolar narcotic toxicants. The 20th percentile PET values are one to two orders of magnitude higher than published screening-level guidelines, suggesting that the screening-level guidelines will provide overly conservative assessments in most cases. Relevant spiked sediment toxicity data are very limited but seem consistent with the probabilistic model; additional testing could be conducted to confirm the model's predictions.

“…However, no chemicals other than HCBD were identified as potentially significant contributors to toxicity in any sample containing less than 3 mg/kg 1%OC HCBD. Specifically, hexchlorobenzene concentrations in all samples were well below the no‐effect concentrations observed in spiked sediment toxicity tests [9,34], toxic index values for other chlorinated benzenes [12] were well below levels expected to produce toxicity, and toxic index values for PAHs [11] were below the level associated with a 25% probability of toxicity. Additionally, Sferra et al [35] examined mercury concentrations in the dilution study as well as subsequent site‐specific tests and concluded that mercury‐related toxicity was not evident.…”

Section: Resultsmentioning

confidence: 99%

Three lines of evidence in a sediment toxicity evaluation for hexachlorobutadiene

Fuchsman

Sferra²,

Barber

2000

Self Cite

Three approaches were used in a site‐specific sediment toxicity evaluation for hexachlorobutadiene (HCBD), a chemical not previously tested for toxicity in sediment. The results of a sediment dilution study, spiked sediment toxicity tests, and a probabilistic model based on equilibrium partitioning theory were used to estimate ecological effects thresholds for HCBD in sediments of a Gulf Coast estuary. Twenty‐nine sediment samples, including 11 undiluted samples and six dilution series, were tested for toxicity under estuarine conditions (10%0 salinity) using Hyalella azteca and Leptocheirus plumulosus. Site sediment was used as diluent, and all samples were assayed for a range of organic and inorganic chemicals. A logistic relationship was observed between HCBD concentrations and organism response, and nonlinear regression explained approximately 90% of the observed variation in amphipod survival as a function of HCBD. Spiked sediment toxicity test results generally agreed with the results of the dilution study, demonstrating the causality of the observed concentration–response relationship. Effects thresholds were estimated as HCBD concentrations corresponding to 80% amphipod survival. The most conservative effects thresholds from the spiked sediment and dilution studies were 0.63 mg/kg normalized to 1% total organic carbon (mg/kg1%OC) for H. azteca and 1.4 mg/kg1%OC for L. plumulosus. Aquatic LC50s for 10 species and a measured acute–chronic ratio from the published literature were used to predict a distribution of sediment effects thresholds for HCBD, with 10th and 90th percentile values of 2.6 and 45 mg/kg1%OC, respectively. The predicted and observed sediment effects thresholds thus agreed relatively well, although the H. azteca and L. plumulosus test results from this study seem to be somewhat more conservative than the majority of published aquatic toxicity test results.