Integrated risk prioritization of rubber additives based on hazard ranking and exposure characterization

Rubber products are widely used in transportation, construction, and electronics. At the same time, concern is growing over the environmental and human health risks of rubber additives. However, systematic screening is still limited because few workflows link hazard information with industrial formulation loading data. Here, we developed an integrated high-throughput screening workflow for rubber additives by harmonizing multiple authoritative databases to compile chemical structures, functional information, and representative formulation data. Multi-model and multi-endpoint quantitative structure-activity relationship (QSAR) predictions were integrated using two hazard-ranking strategies, and additional substances of concern were identified using criteria spanning persistence (P), bioaccumulation (B), mobility (M), and toxicity (T). Hazard-based screening identified 82 priority chemicals. For 12 specific rubber additives with publicly accessible formulation ranges, we further incorporated representative formulation loading and a molecular-weight-based migration potential metric. This step produced an exposure factor and an integrated Risk Index (RI). Under exposure-informed conditions, 2,2,4-trimethyl-1,2-dihydroquinoline (TMQ), N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), and N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD) were identified as top-priority additives by the integrated assessment. Overall, this framework improves the practical relevance of additive prioritization, thereby supporting greener material design, risk management, and substitution assessment in the rubber industry.