ICE-SSD Model: Bridging the Ecological Risk Assessment Gap between Plasticizer and the Substitute

The eco-safety of plasticizer alternative di-isobutyl phthalate (DiBP) has received continued concerns owing to its large usage as a plasticizer and high detection frequency in environments. The concentrations of dibutyl phthalate (DBP) and DiBP in the surface waters ranged from ng/L to μg/L. However, the accurate ecological risk assessment of alternatives is limited by data on toxic effects and potencies. The interspecies correlation estimation (ICE) model combined with the species sensitivity distribution (SSD) model was used to assess the ecological risk of DBP and DiBP. The acute and reproductive predicted no-effect concentrations (PNECs) were derived as 0.05 mg/L and 1.23 μg/L for DBP and 0.16 mg/L and 0.51 μg/L for DiBP based on ICE-SSD models. Our results showed that acute risks (risk quotient (RQ) < 0.1) in mainland China waterbodies, except Hangzhou Bay, were acceptable. The risk quotients indicated that Yangtze River (RQ = 1.55 and 0.48), Hun River (RQ = 1.74 and 6.03), and Hangzhou Bay (RQ = 7.33 and 13.49) had relatively high ecological risk levels based on the reproductive PNECs of DBP and DiBP. Furthermore, the joint probability curves showed that the ecological risks in Hangzhou Bay needed further concern. Thus, the ICE-SSD model could effectively compensate for the lack of toxicity data in risk assessment.