Risk identification of human health, ecotoxicity, and degradation products of azo dyes: development of a priority control list

Azo dyes (ADs) are synthetic colorants with high stability and persistence, posing genotoxic, carcinogenic, and ecological risks. In this study, 56 ADs and 191 predicted degradation products were systematically assessed. Absorption, distribution, metabolism, excretion, and toxicity (ADMET) analysis quantified toxicity endpoints. The Criteria Importance Through Intercriteria Correlation (CRITIC) method determined indicator weights, while the Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) method validated robustness. A standard deviation approach was used to establish a priority control list, identifying seven ADs as being of special concern. Machine learning and factor analysis revealed that electronegativity, molecular volume, and nitro substituents were the key drivers of toxicity, while sulfonate groups reduced risks. Structural traceability confirmed that –N=N– bond cleavage produces hazardous aromatic amines. These findings provide a concise framework for risk identification, regulatory alignment, and prioritization of hazardous dyes, thereby supporting the development of safer alternatives.