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Ecological Threshold for Toxicological Concern (eco-TTC) - applications for environmental risk assessment in various contexts
Citation:
Embry, M., M. Barron, A. Beasley, S. Belanger, J. Brill, D. Chang, D. De Zwart, M. Halder, S. Hughes, A. Kienzler, T. Norberg-King, R. Otter, H. Sanderson, AND P. Wilson. Ecological Threshold for Toxicological Concern (eco-TTC) - applications for environmental risk assessment in various contexts. SETAC North America, Sacramento, CA, November 04 - 08, 2018.
Impact/Purpose:
The Threshold for Toxicological Concern (TTC) is well-established for assessing human safety but has only recently been explored in the ecological context. Ecological Thresholds for Toxicological Concern TTC (eco-TTC) summarize the wealth of ecotoxicological information as Predicted No-Observed Effect Concentrations (PNECs) on diverse chemical substances in the form of probability distributions and enable the prediction of untested chemicals based on a structural attribute, mode of action, or functional use. The approach may be useful for assessing chemicals at early tiers of the risk assessment process, providing hazard perspective on compounds that lack QSARs, guiding product development discussions, and assisting read across or category justifications. An ecotoxicological database was developed based on recent assessments of published data and international chemical management programs. A process has been underway to make these data accessible and useful to stakeholders, the dataset was transitioned from Microsoft Excel and Access into a modern MySQL format, allowing a format that is relational and scalable, facilitating easy access, sharing, and integration with other datasets and tools. The dataset is accessed via a web-based query system that is integrated with PNEC calculator and probability distribution tools. The novel interface allows users to explore the data, upload additional datasets, derive threshold values based on specific criteria, and explore the potential use and application of the eco-TTC concept. An international workshop was held to discuss and evaluate the feasibility of the eco-TTC approach, which included evaluation of several case-studies based on particular decision-contexts (e.g., prioritization and screening, chemical risk assessment, site-specific risk assessment, mixtures, product development, criteria development). With refinement, this approach could be applied and integrated into evaluation strategies (e.g., IATA).
Description:
The Threshold for Toxicological Concern (TTC) is well-established for assessing human safety but has only recently been explored in the ecological context. Ecological Thresholds for Toxicological Concern TTC (eco-TTC) summarize the wealth of ecotoxicological information as Predicted No-Observed Effect Concentrations (PNECs) on diverse chemical substances in the form of probability distributions. These enable the prediction of untested chemicals based on a structural attribute, mode of action, or functional use. The approach may be useful for assessing chemicals at early tiers of the risk assessment process, providing hazard perspective on chemicals that lack QSARs, guiding product development discussions, and assisting read across or category justifications. An ecotoxicological database was developed based on recent assessments of published data and international chemical management programs. This ecotoxicity data is associated with physical chemistry data and curated taxonomic information for the organisms tested, including a process to conclude acute and chronic effects as well as identify the PNEC for exposed ecosystems based on depth and breadth of data. Several mode of action schemes are also included to facilitate development of a best approach for grouping compounds. To make these data accessible and useful to stakeholders, the dataset was transitioned from Microsoft Excel and Access into a modern MySQL format, allowing for a for format that is relational and scalable, facilitating easy access, sharing, and integration with other datasets and tools. The dataset is accessed via a web-based query system that is integrated with PNEC calculator and probability distribution tools. The novel interface allows users to explore the data, upload additional datasets, derive threshold values based on specific criteria, and explore the potential use and application of the eco-TTC concept. An international workshop was held to discuss and evaluate the feasibility of the eco-TTC approach, which included evaluation of several case-studies based on particular decision-contexts (e.g., prioritization and screening, chemical risk assessment, site specific risk assessment, mixtures, product development, criteria development). The discussions and conclusions from that workshop will be presented, including exploration of how this approach could be applied and integrated into evaluation strategies (e.g., IATA).