The accelerating role of microplastics as vectors for synthetic pyrethroids: a critical review of bioaccumulation and trophic transfer in aquaculture ecosystems.

The convergence of microplastic (MP) pollution and the routine application of synthetic pyrethroids presents a complex, synergistic threat to global aquaculture. While the capacity of MPs to vector environmental contaminants is widely recognized, their specific role in altering the toxicokinetics of highly lipophilic and neurotoxic pyrethroids remains a critical regulatory and ecotoxicological blind spot. This critical review systematically evaluates the accelerating role of MPs as vectors for pyrethroids within aquaculture ecosystems. We synthesize the physicochemical mechanisms governing sorption-desorption dynamics, highlighting how polymer crystallinity, weathering, and shifting aquatic parameters dictate vector efficiency. By examining tissue-specific bioaccumulation, the review challenges the conventional "Trojan Horse" paradigm, revealing significant gaps in commercially relevant in vitro digestion models and emphasizing the vulnerability of benthic and whole-consumed species. Furthermore, we dissect the distinct hydrodynamic and trophic transfer pathways across recirculating aquaculture systems (RAS), open-sea cages, and semi-intensive ponds. The review critically addresses the compounded toxicological implications ranging from neuro-stress to compromised immunity and their direct economic consequences on farm performance. Finally, we highlight major regulatory gaps in current Maximum Residue Limits (MRLs) and propose future mitigation strategies, including targeted green pharmacology and advanced filtration technologies, calling for a holistic paradigm shift in aquaculture risk assessment.