Toxicity profiling: An integrated effect-based tool for site-specific sediment quality assessment

A toxicity profile is a toxicological "fingerprint" of an environmental sample, obtained by testing its extract in a battery of bioassays. Each represents a different mode of action. The present work explores the applicability of in vitro toxicity profiles as an effect-based tool for sediment quality assessment. For this purpose, a previously published dataset was used, in which sediment extracts from 15 different locations in the Rhine-Meuse estuary were tested in 5 different bioassays. Three useful approaches could be distinguished for applying toxicity profiles in sediment quality assessment. In the first approach, toxicity profiles are translated into hazard profiles, indicating the relative distance to the desired or acceptable sediment quality status for each toxic mode of action. Hazard profiles can be considered as location-specific characteristics; sampling locations with similar hazard profiles can be classified into clusters. This approach seems directly applicable but requires a very careful selection of a reference toxicity profile that is either measured at a reference location or is designated as a desirable or acceptable toxicity profile for that particular location. In the second approach, toxicity profiles are translated into ecological risk profiles indicating for each toxic mode of action the ratio between the actual measured bioassay response and the bioassay response level that is considered safe for environmental health. This approach has a high ecological relevance but is only feasible for a few modes of action for which toxicity data are available at the ecological level of population or higher that allow derivation of ecologically safe bioassay responses for sediment extracts. In the third approach, toxicity profiles and their derived hazard profiles are used to select samples with unusually or unexpectedly high bioassay responses for further in-depth effect-directed analysis (EDA). EDA is a powerful strategy to identify emerging compounds that contribute significantly to the toxic load on the environment. EDA is an expensive and laborious strategy, however, making it currently suitable only for investigative monitoring on a limited scale and not for routine monitoring. Future perspectives in toxicity profiling include expansion of the battery of bioassays with test methods that cover other toxic endpoints or multiple endpoints, are high throughput, and improve the ecological relevance.