Ongoing production and use of organophosphate tri-esters (tri-OPEs) have resulted in widespread environmental contamination, with levels occasionally exceeding those of legacy persistent organic pollutants (POPs) like PBDEs and HBCDs. Certain tri-OPEs share key traits with POPs, including environmental persistence, bioaccumulation potential, and long-range transport capacity. Moreover, both tri-OPEs and di-OPEs are associated with adverse effects such as reproductive, developmental, and neural toxicity, as well as endocrine disruption.
Current research on the trophic transfer of OPEs has mostly focused on aquatic food chains, and the trophic transfer behavior of OPEs varies among different aquatic food webs. Hence, the transfer behavior of tri- and di-OPEs along terrestrial food chains, and the influence of di-OPEs on the trophic transfer of tri-OPEs, remain unexplored. In a study published in the KeAi journal Environmental Chemistry and Ecotoxicology, researchers revealed the widespread occurrence of tri-OPEs and di-OPEs in the terrestrial ecosystem of the Tibetan Plateau and confirmed the trophic dilution behavior of OPEs, along with the underlying mechanisms, in a representative plateau terrestrial food chain (plant–plateau pika–eagle).
Using long-term field observations and stable isotope analysis in the Nam Co Basin of the Tibetan Plateau, the team identified an ideal plant–plateau pika–eagle food chain for OPE behavior studying.
"Our research results indicated that, represented by the alkyl OPEs, the logarithmic molar ratios between di-OPEs and their corresponding tri-OPEs in biota were higher than those of soil, and positive correlated with trophic levels, suggesting bio-transformation along the food chain,"shares corresponding author Jianjie Fu, a professor at the Zhejiang Key Laboratory of Environment and Health of New Pollutants, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences.
The research team hypothesized that OPE metabolism in plants was weaker than that in plateau pika and eagle, thus mediating trophic dilution along the terrestrial food chain. "To test this hypothesis globally, we reviewed tri-OPE accumulation across taxa, revealing relatively low concentrations in high-trophic-level and/or endothermic organisms (birds and mammals)," adds Fu. "Compared to lower-trophic-level and ectothermic organisms (fish and reptiles), these endotherms possess more diverse enzyme systems and greater metabolic capacity to degrade exogenous lipophilic compounds."
Notably, contaminants susceptible to metabolic transformation typically exhibit trophic dilution along the food chain, which highlighted the significance of metabolism to OPEs trophic transfer potential along terrestrial food chain.
