Novel Bayesian Method to Derive Final Adjusted Values of Physicochemical Properties: Application to 74 Compounds

Abstract

Accurate values of physicochemical properties are essential for screening semivolatile organic compounds for human and environmental hazard and risk. In silico approaches for estimation are widely used, but the accuracy of these and measured values can be difficult to ascertain. Final adjusted values (FAVs) harmonize literature-reported measurements to ensure consistency and minimize uncertainty. We propose a workflow, including a novel Bayesian approach, for estimating FAVs that combines measurements using direct and indirect methods and in silico values. The workflow was applied to 74 compounds across nine classes to generate recommended FAVs (FAVRs). Estimates generated by in silico methods (OPERA, COSMOtherm, EPI Suite, SPARC, and polyparameter linear free energy relationships (pp-LFER) models) differed by orders of magnitude for some properties and compounds and performed systematically worse for larger, more polar compounds. COSMOtherm and OPERA generally performed well with low bias although no single in silico method performed best across all compound classes and properties. Indirect measurement methods produced highly accurate and precise estimates compared with direct measurement methods. Our Bayesian method harmonized measured and in silico estimated physicochemical properties without introducing observable biases. We thus recommend use of the FAVRs presented here and that the proposed Bayesian workflow be used to generate FAVRs for SVOCs beyond those in this study.

Temperature and indoor environments

“…It has been shown, however, that QSAR algorithms as implemented in SPARC and EPI Suite deliver very different results for many compounds. 41 Rodgers et al 85 applied a Bayesian method to calculate accurate values of physicochemical properties for 74 compounds.…”

“…It has been shown, however, that QSAR algorithms as implemented in SPARC and EPI Suite deliver very different results for many compounds 41 . Rodgers et al 85 applied a Bayesian method to calculate accurate values of physicochemical properties for 74 compounds. The authors also present molar internal energies of solvent/solvent or solvent/air phase transfer ( ΔU° ), which can be used to calculate temperature‐dependent partition coefficients according to van't Hoff's law.…”

A holistic modeling framework for estimating the influence of climate change on indoor air quality

“…Usually, values for 298 K are available. Factors and enthalpies for conversion to other temperatures have been published for various substances 29,122,123 …”

“…Factors and enthalpies for conversion to other temperatures have been published for various substances. 29,122,123 Liu et al ( 2013) 124 pointed out that the assumption of instantaneous gas/particle equilibrium can lead to large errors in the estimation of indoor SVOC concentrations. Therefore, in this work, the estimation of SVOC concentration is treated as a post-processing module, that is, first the indoor TSP is quantified and then the sorbed SVOC on the particles is estimated using Equation (3)…”

Filling in the Blanks: A New Tool to Predict Chemical Pathways from Production to Exposure

“…Miriam Diamond, a professor at the University of Toronto’s Department of Earth Sciences and School of the Environment, has published work 11 indicating that the computational models that form the basis of PROTEX-HT were not always reliable for certain types of molecules. Diamond, who was not involved in the current study, says the uncertainties surrounding PROTEX-HT preclude acting upon its maximum allowable tonnage estimates for the time being.…”