Review of 6PPD-quinone environmental occurrence, fate, and toxicity in stormwater

Abstract

The antioxidant N-(1,3-dimethylbutyl)-N?-phenyl-p-phenylenediamine (6PPD) is widely used to improve the durability of rubber. However, one of its transformation products, 6PPD-quinone (6PPD-Q), was recently found to be toxic. Herein, we aim to provide a comprehensive understanding of 6PPD-Q ecological and human-linked toxicity to facilitate the preparation of robust and specific environmental standards and policies. We reviewed 6PPD-Q environmental occurrence, fate, and toxicity originating from stormwater runoff and summarised its origin and environmental shaping conditions. Stormwater runoff was found to be the main driver in introducing 6PPD-Q into the environment. 6PPD-Q detection in roadside soils and other vehicle-related environments indicates that vehicle tyres are the major source of this compound; its presence in the soil can contaminate plants, thereby entering the food cycle. 6PPD-Q air concentrations were higher at roadside sites than at secluded building sites. Nevertheless, the mechanisms underlying 6PPD-Q toxicity and their relationship to various environmental factors, other contaminants, and removal technologies remain unknown. Addressing these gaps can help raise 6PPD-Q environmental risk awareness and facilitate development innovations to mitigate 6PPD-Q-linked risks.