Abstract
Several tons of chemicals are released every year into the environment and it is essential to assess the risk of adverse effects on human health and ecosystems. Risk assessment is expensive and time-consuming and only partial information is available for many compounds. A consolidated approach to overcome this limitation is the Threshold of Toxicological Concern (TTC) for assessment of the potential health impact and, more recently, eco-TTCs for the ecological aspect. The aim is to allow a safe assessment of substances with poor toxicological characterization. Only limited attempts have been made to integrate the human and ecological risk assessment procedures in a “One Health” perspective. We are proposing a strategy to define the Human-Biota TTCs (HB-TTCs) as concentrations of organic chemicals in freshwater preserving both humans and ecological receptors at the same time. Two sets of thresholds were derived: general HB-TTCs as preliminary screening levels for compounds with no eco- and toxicological information, and compound-specific HB-TTCs for chemicals with known hazard assessment, in terms of Predicted No effect Concentration (PNEC) values for freshwater ecosystems and acceptable doses for human health. The proposed strategy is based on freely available public data and tools to characterize and group chemicals according to their toxicological profiles. Five generic HB-TTCs were defined, based on the ecotoxicological profiles reflected by the Verhaar classes, and compound-specific thresholds for more than 400 organic chemicals with complete eco- and toxicological profiles. To complete the strategy, the use of in silico models is proposed to predict the required toxicological properties and suitable models already available on the VEGAHUB platform are listed.
Highlights
Toxicological profiling of substances released into the environment is essential to assess the risk of adverse effects on human health, following different routes of exposure.The process is expensive and time-consuming and, today, the information available for so many compounds is still partial
The aim of this study was to develop a strategy for the definition of generic and compound-specific HB-Threshold of Toxicological Concern (TTC) for the aquatic environment as safe freshwater concentrations for human and ecological receptors at the same time, using public data and the in silico tools implemented in the VEGAHUB platform (www.vegahub.eu)
5 Human-Biota TTCs (HB-TTCs) values are defined because the Ecotoxicological Threshold of Toxicological Concern (eco-TTC) we propose are always lower than the Quality Standards (QS) values derived from the human TTC as defined by Cramer [29]
Summary
Toxicological profiling of substances released into the environment is essential to assess the risk of adverse effects on human health, following different routes of exposure.The process is expensive and time-consuming and, today, the information available for so many compounds is still partial. Toxicological profiling of substances released into the environment is essential to assess the risk of adverse effects on human health, following different routes of exposure. To facilitate the hazard and risk assessment of chemicals, whether recently developed or already available on the market, the concept of Threshold of Toxicological Concern (TTC or hTTC) was introduced in the 90s [1,2]. TTC is a generic human exposure threshold below which there would be no appreciable health effects and it is generally used when there are no chemical-specific toxicity data [3,4,5]. HTTC is a consolidated approach in risk assessment to estimate the dangers of chemicals from different routes and sources of exposure such as diet and inhalation [6,7,8,9,10,11], or for specific groups of contaminants [12,13,14,15,16,17,18]
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