Society of Environmental Toxicology and Chemistry

7.02 - Advancing the Science of Difficult to Test Substances

Track:  7. Moving Beyond - Cross Cutting Themes, Emerging, Transdisciplinary and Outlying Topics

Description

Difficult to test substances (DTS) display physical-chemical or compositional properties which introduce significant challenges when attempting to assess environmental hazard using standard test methods. Common difficult to test properties include volatility, insolubility, adsorption, rapid degradability, ionizability, surface activity and presence of multiple, variable and/or unknown constituents (e.g., substances of Unknown or Variable Composition, Complex Reaction Products, or Biological Materials; UVCBs). These properties can interfere with exposure stability, substance bioavailability, and analytical verification in test systems – influencing compatibility with test systems, feasibility of experimental methods, and applicability of predictive models. As such, significant innovation and adaptation of standardized methodologies is often required to successfully test and assess the hazards/risks that DTS may pose to the environment. This session aims to: 1) Explore scientific and regulatory challenges associated with the hazard and risk assessment of DTS; 2) Discuss successes and failures in the adaptation and/or application of standard test methodology for DTS; and 3) Highlight technical advancements and novel methodologies that can be applied to generate and/or evaluate DTS data. The scope of this session aims to be broad, targeting case studies, collaborative synthesis efforts, and regulatory outlooks focused on testing and assessing environmental hazard and risk of DTS. By bringing together experts from industry, academia, regulatory bodies and contract research organizations, we aim to foster dialogue on best practices and future testing directions. Ultimately, this will help advance the science on DTS, enhancing the scientific robustness of chemical assessments while supporting regulatory compliance, and ethical testing practices.