From contamination to remediation: understanding the toxicity, risk assessment, and degradation pathways of triphenyl phosphate and related organophosphate flame retardants in water and soil

Abstract

Triphenyl Phosphate (TPhP), a widely used organophosphate flame retardant (OPFR), has been increasingly detected in the environment via soil and water matrices, due to its persistence and potential toxicity. While numerous studies have investigated its behavior and remediation in aquatic environments, limited attention has been paid to study the TPhP occurrence and treatment in soil. This disparity is attributed to the inherent complexity and heterogeneity of soil, a dynamic matrix composed of diverse mineral particles, organic matter, and microbial populations. Unlike water, soil conditions are difficult to replicate in controlled environments, and factors such as adsorption to organic matter and restricted oxygen diffusion can significantly impede degradation processes. These limitations result in prolonged persistence and delayed remediation in terrestrial settings. This review aims to bridge the knowledge gap in OPFR remediation and promote sustainable solutions for mitigating TPhP and other OPFR-related contaminants from the environment. Remediation strategies, including biological, chemical, and substance-based natural approaches, are discussed, with an emphasis on their degradation mechanisms and removal efficiencies. Despite the limited research on TPhP degradation in aquatic environments, remediation strategies for soil and sediments remain largely unexplored, underscoring the need for further research in this area. In addition, this review explores the toxicity, global distribution, and bioaccumulation risks of TPhP and related OPFRs in both water and soil environments. The paper concludes by addressing key challenges and outlining strategic approaches and potential solutions for the effective remediation and risk management of TPhP and related OPFRs in environmental systems.