First CST Group Standards Unveiled, with REACH24H Advancing Toxicological Assessment Development

On November 28, 2025, the Chinese Society of Toxicology (CST) officially released its first batch of group standards, marking a major step forward in the standardization of toxicological assessment in China. The two standards were approved and came into effect upon their publication:

• T/CST 001-2025 Guidance of the Approach on Threshold of Toxicological Concern

• T/CST 002-2025 Guiding Principles for Integrated Approaches to Testing and Assessment

Background and Development

The development of these standards began in early 2021 under the supervision of the CST Standards Working Committee. Over four years, the project team conducted extensive reviews of domestic and international standards, regulatory requirements, and the latest scientific advancements. The process included multiple expert discussions, industry consultations, and iterative revisions to ensure the creation of high-quality technical documents.

REACH24H Consulting Group, a key contributor to the drafting process, actively participated throughout the entire development of the standard and contributed its professional expertise to enhance the scientific rigor and standardization of toxicological assessment methodologies.

Overview of the Standards

1. Guidance of the Approach on Threshold of Toxicological Concern (TTC)

The TTC method is an exposure-based risk assessment tool that evaluates the safety of chemical substances in cases where specific toxicological data are limited or unavailable. This standard provides:

• A clear explanation of the scientific principles behind the TTC approach.

• General threshold values and standardized application procedures.

• Practical guidance for applying the TTC method across various product categories, including cosmetics, pharmaceuticals, and medical devices.

2. Guiding Principles for Integrated Approaches to Testing and Assessment (IATA)

IATA is a modern framework that integrates existing data with new information obtained through testing or novel approaches. This standard:

• Defines core concepts such as New Approach Methodologies (NAMs), Adverse Outcome Pathways (AOPs), Weight of Evidence (WoE), and Defined Approaches (DAs).

• Outlines the five key steps of IATA: problem formulation, data collection, evidence analysis, new data generation, and conclusion evaluation

• Emphasizes the importance of uncertainty analysis in risk assessment conclusions.

Global Context

The release of these standards aligns with global trends in toxicological safety evaluation, which increasingly emphasize reducing reliance on animal testing and adopting alternative methods. Recent international developments include:

• The U.S. FDA's Roadmap to Reducing Animal Testing in Preclinical Safety Studies (April 2025).

• The U.K. government's Replacing animals in science: A strategy to support the development, validation and uptake of alternative methods (November 2025).

In this context, the CST standards demonstrate China's commitment to advancing toxicological science. As one of the drafting organizations for the two standards, REACH24H has consistently kept pace with global advances in toxicological science and technology. Looking ahead, REACH24H will continue to leverage its technical strengths to support enterprises in better understanding and implementing new standards, and to work together in advancing toxicological assessment technologies and promoting green and sustainable industry development.