On enumeration of congeners of common persistent organic pollutants

Congeners are molecules based on the same carbon skeleton but different by the number of substituents and/or a substitution pattern. Various Persistent Organic Pollutants (POPs) exist in the environment as families of halogen substituted congeners and/or their hydroxyl and methoxy substituted derivatives. Numbers of possible congeners resulting from substitution of a parent POP molecule with only one type of chemical group are generally available. At the same time, numbers of mixed-substituent congeners have not been counted and presented yet, although there is an increasing interest in such as is the increasing number of research articles presenting results on already identified Cl−/Br−mixed type congeners and/or their HO-/CH₃O-mixed metabolites. We have enumerated and counted possible mixed-substituent congeners of common POPs. This article presents the obtained numbers for congener families of benzene, naphthalene, biphenyl, diphenyl ether, dibenzo-p-dioxin, dibenzofuran, anthracene, pyrene and others and obtained by substitution of up to five chemical group types.     

Predicting logarithmic values of the subcooled liquid vapor pressure of halogenated persistent organic pollutants with QSPR: How different are chlorinated and brominated congeners?

Logarithmic values of the subcooled liquid vapor pressure (log P_L) were estimated for 1436 polychlorinated and polybrominated congeners of benzenes, biphenyls, dibenzo-p-dioxins, dibenzofurans, diphenyl ethers and naphthalenes by employing the Quantitative Structure–Property Relationships (QSPR) approach. The QSPR model developed with GA–PLS technique was characterized by satisfactory goodness-of-fit, robustness and the external predictive performance (R²Y = 0.970, Q_CV² = 0.970, Q_Ext² = 0.966, RMSE_C = 0.21, RMSE_CV = 0.22 and RMSE_P = 0.22). The externally validated model has been applied to predict subcooled liquid vapor pressure of uninvestigated halogenated persistent organic pollutants. Moreover, a simple arithmetic relationship between logarithmic values of subcooled liquid vapor pressures in pairs of chloro- and bromo-analogues has been found. This relationship can be used for estimating log P_L of a brominated compound, whenever log P_L of its chlorinated counterpart is known, without necessity of performing any time-consuming computations.     

Modeling the overall persistence and environmental mobility of sulfur-containing polychlorinated organic compounds

Background, aim, and scope  

Experimental data on partition coefficients and environmental half-lives of sulfur analogs of polychlorinated organic compounds are scarce. Consequently, little is known about their overall persistence and long-range transport potential, which are the most vital measures in the environmental exposure assessment. We performed Multimedia Modeling of environmental fate and transport to complement this paucity of scientific data. The main aim of our study was to investigate whether the sulfur analogs of polychlorinated dibenzo-p-dioxins, -dibenzofurans, and -diphenylethers are as environmentally persistent and/or mobile as their oxygen counterparts and to propose the environmental exposure-related classification of the examined sulfur compounds.