Evaluation of the OECD POV and LRTP screening tool for estimating the long-range transport of organophosphate esters.

Scientists and decision makers need accurate, accessible and fast tools to assess and prioritize the persistence (POV) and environmental long-range transport potential (LRTP) of chemicals. Here we evaluated the Organisation for Economic Co-operation and Development (OECD) POV and LRTP Screening Tool ("the Tool") with respect to the POV and LRTP estimates that the Tool provides for organophosphate esters (OPEs). We found that the use of default parameter values could significantly underestimate POV and LRTP values of OPEs and, potentially, other Persistent Mobile Organic Compounds (PMOCs), by not accounting for episodic atmospheric transport and poleward river-based transport in the northern hemisphere. Specifically, sensitivity and Monte Carlo uncertainty analyses indicate that non-chlorinated OPEs could be subject to LRTP when uncertainties in gas-particle partitioning and its implications for atmospheric degradation are considered, and chlorinated OPEs when river-based transport is considered. Further, the analyses showed strong dependence of results on the accuracy of the environmental half-lives used as input parameters. We suggest that the Tool could be modified to include an optional "Arctic (PMOC) LRTP setting" that incorporates episodic atmospheric and river-based transport as well as decreased environmental half-lives due to cold temperatures.