Environmental chemicals with endocrine-disrupting effects have raised global concerns owing to their increasing adverse outcomes toward different marine taxa. However, deriving predicted no-effect concentrations (PNECs) of endocrine-disrupting chemicals remains challenging, especially when utilizing non-apical endpoints. Here, a species sensitivity distribution method integrating taxon-specific adverse outcome pathways (AOPs) was developed and applied to derive saltwater PNECs of tributyltin. Our results revealed that, besides imposex in molluscs, some non-apical endpoints (morphological alterations and hormone levels) in fish and crustaceans were as decisive as apical ones. Taxa sensitivity followed the order of fish, crustaceans and molluscs. The hazardous concentration for 5% of species (0.693 ng/L) based on reproduction data was lower than that (1.53 ng/L) based on growth data (including developmental delay and morphological alterations). The PNEC, considering combined apical and non-apical endpoints, was 1.3 ng/L (95% confidence intervals: 0.23~7.1 ng/L), 2.4 times lower than that (3.1 ng/L, 95% confidence intervals: 0.52~18.2 ng/L) based solely on apical endpoints. Imposex data from field studies on gastropods confirmed the reliability of PNEC for supplementation of non-apical AOP-related endpoints. This study provides an innovative perspective that taxon-specific AOPs enable effective identification of non-apical toxicity endpoints associated with endocrine disrupting effects across taxa and derivation of robust PNEC to protect marine species.
 

tributyltin,predicted no-effect concentration,species sensitivity distribution,non-apical endpoints,taxa