Strategies to Reduce Uncertainties from the Best Available Physicochemical Parameters Used for Modeling Novel Organophosphate Esters across Multimedia Environments

Organophosphate esters (OPEs) raise growing environmental
and human
health concerns globally. However, numerous novel OPEs lack data on
physicochemical properties, which are essential for assessing environmental
fate, exposure, and risks. This study predicted water solubility (Sw), vapor pressure (Vp), octanol–water partition coefficient (Kow), and octanol–air partition coefficient (Koa) at 25 °C for 46 novel OPEs by identifying
optimal in silico tools and establishing prediction
strategies based on molecular weights (MWs). Prediction discrepancies
between in silico tools increased with MWs and structural
complexity. Method evaluations for compounds with MWs > 450 g/mol
suggest that COSMOtherm is advantageous in predicting Sw and Vp for alkyl-OPEs, while
SPARC is better for predicting Vp for
aryl- and halogenated-OPEs. For compounds with MWs > 500 g/mol,
COSMOtherm
and SPARC are recommended for Kow and Koa prediction, respectively. For smaller OPEs,
average values from the top three of COSMOtherm, SPARC, EPI Suite,
and OPERA, ranked by validation on traditional flame retardants, are
recommended. Using improper software could cause deviations in multimedia
distribution and overall persistence in the environment by up to 83
and 350%, respectively. The present data and prediction strategy are
useful to enhance the reliability of environmental fate, exposure,
and risk assessments of various OPEs and emerging contaminants.