A review of sources, fate, levels, toxicity, exposure and transformations of organophosphorus flame-retardants and plasticizers in the environment

Organophosphate esters (OPEs) are esters of phosphoric acid that are increasingly used as plasticizers and by the flame-retardants industries as replacement for the regulated polybrominated diphenyl ethers. The most commonly classes of these pollutants are the chlorinated- and non-chlorinated-OPEs. The extent and magnitude of OPEs occurrence in the environment, combined with striking structural similarities to toxic organophosphorus pesticides has led to public concern over risk posed by these compounds. Using peer-reviewed literature published from the last decade (2010–2019), concentrations and distributions of commonly studied OPEs based on their occurrence in different matrices around the globe were evaluated and reported. These pollutants have a wide range of physicochemical properties such as their water solubility's, logKow value, vapour pressure and bioconcentration factors (BCFs) which are very important factors in assessing their behaviour in different environmental matrices. Despite progress in research on OPEs over the years, full understanding of the environmental behaviour and fate of these pollutants are still elusive. Sources by which these pollutants enter the environment in conjunction with their concentrations together with their toxicities, estimated daily intakes, transformation products and fates are reviewed. It is envisaged that this review will heighten the importance of identifying emerging issues, data gaps and provide a future research agenda for OPEs.