Contrasting effects of micro- and nanoplastics on accumulation and toxicity of tris(1,3-dichloro-2-propyl) phosphate in zebrafish embryo revealed by toxicokinetic-toxicodynamic model

Micro(nano)plastics (MNPs) are both pollutants and carriers of other toxic pollutants, which produce complex combined effects with co-exposed pollutants. Tris (1,3-dichloro-2-propyl) phosphate (TDCIPP), a widely used organophosphate ester (OPE) plasticizer and flame retardant in plastics, was selected to examine how microplastics (MPs) and nanoplastics (NPs) modulate its bioaccumulation and toxicity in zebrafish embryos. The results indicated that MPs did not significantly affect the bioaccumulation or toxicity of TDCIPP in embryos. In contrast, NPs increased the accumulation of TDCIPP in embryos, thereby enhancing adverse effects on hatching, development and survival. Toxicokinetic (TK) and toxicodynamic (TD) models were further applied to validate the influence of MPs and NPs on the bioaccumulation and toxicity of co-existing pollutants. The TK-TD modeling revealed that MPs had no significant effect on the bioconcentration factor (BCF) or internal threshold concentration (CIT) of TDCIPP, whereas NPs significantly increased BCF and decreased CIT. Moreover, the ratio CIT/BCF was found to explain the differential toxicity effects of TDCIPP in the presence of MPs and NPs. This study quantified the disparate effects of MPs and NPs at environmental concentrations on the bioaccumulation and toxicity of TDCIPP from the TK-TD perspective, contributing to a better understanding of the toxicity mechanism of the mixture.