Risk-based prioritization of organic substances in the Canadian National Pollutant Release Inventory using an evaluative regional-scale multimedia mass balance model

Prioritizing molecular formulae identified by non-target analysis through high-throughput modelling: application to identify compounds with high human accumulation potential from house dust

Because it is typically not possible to pursue compound identification efforts for all chemical features detected during non-target analysis (NTA), the need for prioritization arises. Here we propose a strategy that ranks chemical features detected in environmental samples based on a model-derived metric that quantifies a feature's attribute that makes it desirable to elucidate its structure, e.g., a high potential for bioaccumulation in humans or wildlife. The procedure involves the identification of isomers that could plausibly represent the molecular formulae assigned to NTA-detected chemical features. For each isomer, the prioritization metric is calculated using properties predicted with high-throughput methods. After the molecular formulae are ranked based on the average values of the prioritization metric calculated for all isomers assigned to a formula, the highest ranked molecular formulae are prioritized for structure elucidation. We applied this workflow to features identified in house dust, using the ratio of chemical intake through dust ingestion to chemical concentration in blood (dose-to-concentration ratio, DCR) as the prioritization metric. Collections of isomers for the molecular formulae were assembled from the PubChem database and DCR was estimated using partitioning and biotransformation properties predicted for each isomer using quantitative structure property relationships. The ten top-ranked molecular formulae with notably lower average DCR-values represented mostly compounds already known to be indoor pollutants of concern, such as two polybrominated diphenyl ethers, bis(2-ethylhexyl) tetrabromophthalate, tetrabromobisphenol A, tris(1,3-dichloroisopropyl)phosphate and the azo dye disperse blue 373.

New Sustainability Perspectives on Pollutant Releases from Canada's Nuclear Sector

This novel characterization of new Canadian radionuclide release data aims to both deepen the understanding of the nature and magnitude of present-day emissions from nuclear facilities and accelerate the tracking of this sector's progress toward United Nations Sustainable Development Goal (SDG) 12 (responsible consumption and use patterns) and target 12.4 (environmentally sound chemicals management). Further novel perspectives on the role of this data as an indicator of sustainability are discussed by merging it with other pollutant releases from this sector, as reported to the National Pollutant Release Inventory (NPRI), to fill gaps in the latter's substance coverage. These public data sets are processed and analyzed using Tableau software and the Organization for Economic Cooperation and Development's framework for using pollutant release and transfer (PRTR) data in sustainability analysis. Findings confirm that radionuclide emissions to air and direct discharges to water from present-day Canadian nuclear facilities do not contribute significantly to national-scale radionuclide contamination. Moreover, findings validate the usefulness of combining various PRTR (and similar) data to address substance coverage gaps and set a global precedent for strengthening PRTR indicator power in SDG 12 evaluation. This work underscores the value of interoperable data in accelerating knowledge translation of PRTRs in the lens of sustainable development.

A methodology to screen priority toxins in pollutant release inventories

Pollutant release inventories are used for environmental policy making to reduce toxic pollutants, even though the quantity-based inventory analysis does not take into account the relative toxicity of pollutants. To overcome this limit, life cycle impact assessment (LCIA)-based inventory analysis was developed but still has a high uncertainty from modelling the site- and time-specific fates and transports of pollutants. Thus, this study develops a methodology to evaluate toxicity potentials based on the concentration of pollutants in the exposure to humans in order to circumvent the uncertainty and subsequently screen priority toxins in pollutant release inventories. This methodology combines (i) analytical measurement of the concentration of the pollutants exposed to humans; (ii) application of toxicity effect characterization factors for pollutants; and (iii) identification of priority toxins and industries based on the toxicity potential evaluation results. To demonstrate the methodology, a case study is considered, evaluating toxicity potentials from the ingestion of heavy metals in seafood organisms and then identifying priority toxins and industry sectors in a pollutant release inventory. The results of the case study show that the methodology-based priority pollutant is different from the quantity- and LCIA-based ones. Therefore, the methodology can contribute to making effective environmental policy.