Using quantitative structural property relationships, chemical fate models, and the chemical partitioning space to investigate the potential for long range transport and bioaccumulation of complex halogenated chemical mixtures

Abstract

Some substances are mixtures of very large number of constituents which vary widely in their properties, and thus also in terms of their environmental fate and the hazard that they may pose to humans and the environment. Examples of such substances include industrial chemicals such as the chlorinated paraffins, technical pesticides such as toxaphene, and unintended combustion side products, such as mixed halogenated dibenzo-p-dioxins and dibenzofurans. Here we describe a simple graphical superposition method that could precede a more detailed hazard assessment for such substances. First, partitioning and degradation properties for each individual constituent of a mixture are estimated with high-throughput quantitative structure-property relationships. Placed in a chemical partitioning space, i.e. a coordinate system defined by two partitioning coefficients, the mixtures appear as 'clouds'. When model-derived hazard assessment metrics, such as the potential for bioaccumulation and long range transport, are superimposed on these clouds, the resulting maps identify the constituents with the highest value for a particular parameter and thus potentially the greatest hazard. The maps also indicate transparently how the potential for long range transport and bioaccumulation is dependent on structural attributes, such as chain length, and the degree and type of halogenation. In contrast to previous approaches, in which the mixture is represented by a single set of properties or those of a few selected constituents, the whole range of environmental fate behaviors displayed by the constituents of a mixture are being considered. The approach is illustrated with three sets of chemical substances.

Screening of Atmospheric Short- and Medium-Chain Chlorinated Paraffins in India and Pakistan using Polyurethane Foam Based Passive Air Sampler

“…1 The results suggest C10 and C11 are the largest of the components in C-42 and C-52, whereas C10 and C-12 are the highest in C-72 (see SI Figure S2). Unfortunately, the commercial CP mixtures in South Asia, India, and Pakistan, are not well documented, therefore, the composition of the mixtures are not available.…”

“…There are more than hundred thousand isomers, 1 which are very inert, water insurable and produced by chlorination of n-paraffin or paraffin wax.…”

Current status of short- and medium chain polychlorinated n-alkanes in top predatory fish across Canada

“…These homologue groups are also found in biota from remote locations and the Arctic (Tomy et al, 2000;Reth et al, 2006). Homologue groups with 5-7 chlorines have a log K oa between 6.5 and 10, which translates in an increased potential to cycle between the atmospheric and aqueous phase, thus increasing their potential for long range atmospheric transport (Gawor and Wania 2013). Moreover, sPCAs with 11-12 carbons and 6-8 chlorines are the major components associated with atmospheric deposition (Wang et al, 2013).…”

Chlorination pattern effect on thermodynamic parameters and environmental degradability for C 10 -SCCPs: Quantum chemical calculation based on virtual combinational library

“…The relationship between other basic properties such as vapor pressures and Henry's law constants with carbon chain length and chlorination degree was also proposed based on limited data for SCCPs (Drouillard et al, 1998). Moreover, estimated values from theoretical calculations were also introduced for limited congeners (Gawor and Wania, 2013;Glüge et al, 2013;Wang et al, 2012). EPI Suite™ and SPARC chemical prediction programs were used to calculate the subcooled-liquid vapor pressures and octanol-air partition coefficients for selected SCCP congeners with chlorine content of 50%-70% , while calculations of other physicochemical properties such as subcooled-liquid solubility in water and octanol, subcooled-liquid vapor pressure, Henry's law constant for water and octanol, and octanol-water partition coefficient were carried out for limited SCCP and MCCP congeners by adopting three tools, COSMOtherm, SPARC, and EPI Suite™ (Glüge et al, 2013).…”

“…EPI Suite™ and SPARC chemical prediction programs were used to calculate the subcooled-liquid vapor pressures and octanol-air partition coefficients for selected SCCP congeners with chlorine content of 50%-70% , while calculations of other physicochemical properties such as subcooled-liquid solubility in water and octanol, subcooled-liquid vapor pressure, Henry's law constant for water and octanol, and octanol-water partition coefficient were carried out for limited SCCP and MCCP congeners by adopting three tools, COSMOtherm, SPARC, and EPI Suite™ (Glüge et al, 2013). In addition, chemical fate models and the chemical partitioning space were coupled with quantitative structure-property relationships to investigate the potential of complex SCCP mixtures for long range transport and bioaccumulation (Gawor and Wania, 2013). Most recently, the gaseous reaction of ten SCCP molecules with hydroxyl radical was studied via quantum chemical calculations Liu et al, 2015).…”