16:45 〜 17:00
[HCG19-05] Ecological Risk Assessment of the Plasticizer TOTM Leaching from Plastics into Aquatic Environments
キーワード：可塑剤、トリメリット酸トリオクチル (TOTM)、生態リスク、プラスチック汚染
Plastic pollution has been reported worldwide, affecting various aquatic environments, including rivers, oceans, tap water, and sediments. Numerous studies have examined plastic residues in aquatic environments and their biological toxicity. Plastics contain additives, including plasticizers, which can comprise 10–70 % of their composition. Among these additives, plasticizers are not chemically bonded to the plastic matrix, making them prone to leaching into the environment. As plastic pollution worsens, contamination by plasticizers is also expected to increase. Some plasticizers have been subject to regulatory restrictions in Japan, the United States, and the European Union due to concerns over their environmental persistence and potential toxicity. Meanwhile, Tris(2-ethylhexyl) trimellitate (TOTM), the focus of this study, has been increasingly used as an alternative to other restricted plasticizers. However, data on its ecotoxicity and environmental concentrations remain limited.
This study assesses the ecological risk of TOTM by measuring its environmental concentration and ecotoxicity. Ecological risk is evaluated using the MEC/PNEC ratio, where MEC represents the Measured Environmental Concentration and PNEC stands for the Predicted No-Effect Concentration. PNEC is derived from NOEC (No Observed Effect Concentration), divided by an assessment factor (AF) to account for uncertainties. The AF varies depending on data quality and availability; for example, when only acute toxicity data from a single species is available, an AF of 1000 is applied.
For the ecotoxicological assessment of TOTM, zebrafish (Danio rerio), a widely used model organism in ecotoxicology, was employed. In the European Union, fish embryos are not classified as protected under animal welfare regulations (Directive 2010/63), meaning toxicity tests using fish embryos do not fall under animal testing regulations. Therefore, this study utilized fish embryos following OECD Test Guideline 236, ensuring compliance with animal welfare considerations. Additionally, environmental monitoring of TOTM was conducted in the Sumiyoshi River (Hyogo Prefecture) over three months to analyze temporal variations. The Sumiyoshi River originates near the highest peak of the Rokko Mountains and flows southward into Osaka Bay, collecting water from multiple tributaries. With a main channel length of 4,073 m and a catchment area of 11.49 km², it flows through an alluvial fan formed by fluvial activity. It is regarded as one of the most pristine rivers in Kobe City, as it receives relatively low domestic wastewater inflow.
The ecotoxicological assessment determined a NOEC of 26.2 µg/L. To the best of our knowledge, this is the first study to report the acute toxicity of TOTM in aquatic organisms. Due to the limited availability of ecotoxicological data, an AF of 1000 was applied, yielding a PNEC of 26.2 ng/L. The MEC obtained from Sumiyoshi River monitoring was 348.2 ng/L, resulting in an MEC/PNEC ratio indicating a high ecological risk. Given the increasing usage of TOTM, further research is essential to evaluate its environmental impact. Additionally, further investigations are required to clarify the relationship between plastic pollution and residual concentrations of plasticizers in the environment.
This study assesses the ecological risk of TOTM by measuring its environmental concentration and ecotoxicity. Ecological risk is evaluated using the MEC/PNEC ratio, where MEC represents the Measured Environmental Concentration and PNEC stands for the Predicted No-Effect Concentration. PNEC is derived from NOEC (No Observed Effect Concentration), divided by an assessment factor (AF) to account for uncertainties. The AF varies depending on data quality and availability; for example, when only acute toxicity data from a single species is available, an AF of 1000 is applied.
For the ecotoxicological assessment of TOTM, zebrafish (Danio rerio), a widely used model organism in ecotoxicology, was employed. In the European Union, fish embryos are not classified as protected under animal welfare regulations (Directive 2010/63), meaning toxicity tests using fish embryos do not fall under animal testing regulations. Therefore, this study utilized fish embryos following OECD Test Guideline 236, ensuring compliance with animal welfare considerations. Additionally, environmental monitoring of TOTM was conducted in the Sumiyoshi River (Hyogo Prefecture) over three months to analyze temporal variations. The Sumiyoshi River originates near the highest peak of the Rokko Mountains and flows southward into Osaka Bay, collecting water from multiple tributaries. With a main channel length of 4,073 m and a catchment area of 11.49 km², it flows through an alluvial fan formed by fluvial activity. It is regarded as one of the most pristine rivers in Kobe City, as it receives relatively low domestic wastewater inflow.
The ecotoxicological assessment determined a NOEC of 26.2 µg/L. To the best of our knowledge, this is the first study to report the acute toxicity of TOTM in aquatic organisms. Due to the limited availability of ecotoxicological data, an AF of 1000 was applied, yielding a PNEC of 26.2 ng/L. The MEC obtained from Sumiyoshi River monitoring was 348.2 ng/L, resulting in an MEC/PNEC ratio indicating a high ecological risk. Given the increasing usage of TOTM, further research is essential to evaluate its environmental impact. Additionally, further investigations are required to clarify the relationship between plastic pollution and residual concentrations of plasticizers in the environment.