Further negative effect of fibrous microplastics to the bioaccumulation and toxicity of decabromodiphenyl ethane on zebrafish

Co-pollution of microplastics (MPs) and novel brominated flame retardants (NBFRs) in aquatic environments is becoming increasingly common in aquatic environments, raising concerns about their comprehensive ecological impacts. This study investigated the effects of fibrous polyethylene terephthalate (PET) MPs on the bioaccumulation and toxicity of decabromodiphenyl ethane (DBDPE) in zebrafish (Danio rerio). In a 28-day water exposure experiment, co-exposure of fibrous MPs and DBDPE significantly increased the bioavailability of DBDPE in zebrafish and prolonged the half-life of DBDPE in vivo. The elimination rates of DBDPE concentration in muscles of single DBDPE exposure and co-exposure groups were 61.58 % and 56.63 %, respectively. Additionally, the co-exposure exacerbated intestinal damage, including structural deterioration and nutrients depletion, disrupted gut microbiota, promoted the enrichment of genes related to reproductive toxicity, and affected the gut-brain axis, indicating complex toxic interactions in zebrafish. Furthermore, genera of Aurantimicrobium, Cypionkella, and Gemmobacter were the gut microbes significantly associated with main differentially expressed genes(DEGs)in the brain. This study emphasized the exacerbating role of fibrous MPs in DBDPE toxicity, providing new insights into the ecological risks posed by the coexistence of MPs and NBFRs in aquatic ecosystems.