A model to predict threshold concentrations for toxic effects of chlorinated benzenes in sediment
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{sub ow} values and aquatic toxicity data extracted from the published literature. The probabilistic distributions of PETs generally increased with chlorination, with 20th percentile values ranging from 3.2 mg/kg{sub 1{degree}OC} for chlorobenzene to 67 mg/kg{sub 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.
- Research Organization:
- McLaren/Hart-ChemRisk, Cleveland, OH (US)
- OSTI ID:
- 20006638
- Journal Information:
- Environmental Toxicology and Chemistry, Vol. 18, Issue 9; Other Information: PBD: Sep 1999; ISSN 0730-7268
- Country of Publication:
- United States
- Language:
- English
Similar Records
Temperature dependence of octanol-water partition coefficient for selected chlorobenzenes
Treatability of hazardous chemicals in soils: Volatile and semivolatile organics