Ecotoxicological environmental risk limits for total petroleum hydrocarbons on the basis of internal lipid concentrations.

A method is described for deriving ecotoxicological environmental risk limits (ERLs) for total petroleum hydrocarbons (TPH). Toxicity data for two oil types (light and heavy) to benthic organisms and corresponding estimated internal lipid concentrations, calculated by equilibrium partitioning, are used as a measure of toxicity by narcosis. It is assumed that uptake by organisms takes place from the aqueous phase, and for partitioning, both oil droplets or coating and organic carbon of sediment are taken into account.

Environmental exposure scenarios: development, challenges and possible solutions.

Under the new REACH system, companies importing, producing and marketing chemical substances will be obliged to register the single substances and to carry out a safety assessment for all identified uses during the life cycle of the substance. This duty will apply to about 10,000 existing substances in the EU market exceeding an annual production or import volume of 10 t per company. If the substance is already known to be dangerous or turns out to be dangerous(1) during the hazard assessment, the registrant is obliged to carry out an exposure assessment and a risk characterisation for all identified uses.

Modeling decreased food chain accumulation of PAHs due to strong sorption to carbonaceous materials and metabolic transformation.

The predictive power of bioaccumulation models may be limited when they do not accountfor strong sorption of organic contaminants to carbonaceous materials (CM) such as black carbon, and when they do not include metabolic transformation. We tested a food web accumulation model, including sorption to CM, on data from a model ecosystem experiment with historically contaminated sediment. In combination with measured CM contents of the sediment, the model gave good fits for the biota that are known not to metabolize PAHs (macrophytes, periphyton, floating algal biomass).

Critical body residues linked to octanol-water partitioning, organism composition, and LC50 QSARs: meta-analysis and model.

To protect thousands of species from thousands of chemicals released in the environment, various risk assessment tools have been developed. Here, we link quantitative structure-activity relationships (QSARs) for response concentrations in water (LC50) to critical concentrations in organisms (C50) by a model for accumulation in lipid or non-lipid phases versus water Kpw. The model indicates that affinity for neutral body components such as storage fat yields steep Kpw-Kow relationships, whereas slopes for accumulation in polar phases such as proteins are gentle.

Environmental quality criteria for organic chemicals predicted from internal effect concentrations and a food web model.

Environmental quality criteria (EQC) for hydrophobic organic chemicals were calculated with a model for bioaccumulation in food webs. The model was calibrated and verified using polychlorinated biphenyl concentrations in food webs of shallow lakes. The EQCs in water and sediment were derived based on internal effect concentrations (IECs) for several modes of toxic action.

A freshwater food web model for the combined effects of nutrients and insecticide stress and subsequent recovery.

A microcosm experiment that addressed the interaction between eutrophication processes and contaminants was analyzed using a food web model. Both direct and indirect effects of nutrient additions and a single insecticide application (chlorpyrifos) on biomass dynamics and recovery of functional groups were modeled. Direct toxicant effects on sensitive arthropods could be predicted reasonably well using concentration-response relationships from the laboratory with representative species.