Due to their exceptionally low water solubilities polychlorinated dibenzodioxins and furans (PCDD/Fs) are strongly and extensively bound to soil and sediment particles. Sorbed PCDD/Fs are distributed among the primary component geosorbents, namely char-like carbonaceous materials, amorphous organic matter, and clays, and the fractional distribution among these geosorbents is hypothesized to change with the total PCDD/F load. Since PCDD/Fs are also highly resistant to decomposition, sorption is a primary determinant of their environmental fates and impacts. Importantly, sorption to soil/sediment particles may modify the bioavailabilities and toxicities of PCDD/Fs in unknown ways, and bioavailability is expected to be geosorbent-specific. The major goals are: (1) to advance fundamental understanding of PCDD/F sorption by these dominant geosorbents comprising soils/sediments, especially at very low environmentally relevant (pptppb) concentrations where carbonaceous materials (e.g. chars) are hypothesized to control soil-water distribution, (2) to determine the differential bioaccessibilities/bioavailabilities of PCDD/Fs sorbed to each key geosorbent type using physiologically based extraction fluid, and mammalian models, (3) to test the hypothesis that mechanistic knowledge of sorption/desorption reactions for PCDD/Fs with individual component geosorbents can be extrapolated to predict site-specific bioaccessibilites and bioavailabilities for contaminated whole soils/sediments, and (4) to evaluate the clay-facilitated formation of PCDD/Fs, and corresponding predioxins/furans, from precursor chlorophenols, and elucidate the underlying mechanistic basis for these reactions. Estimates of PCDD/F bioavailability in soils/sediments are few and inconsistent, hence most risk assessment models for exposure to environmental PCDD/Fs make generic assumptions of 100% bioavailability, irrespective of soil/sediment characteristics. The results of the proposed research will provide the basis for (1) a more mechanistic understanding of the relationship between soil/sediment composition and the human and ecological risks posed by a given total PCDD/F load in soil/sediment, and (2) understanding the prevalence of clay-facilitated PCDD/F formation as an on-going in-situ process leading to unexpected PCDD/F accumulations that threaten human health. Further, it would be of great economic and environmental benefit if certain chars, such as those produced as intentional by-products of biofuels/Csequestration technologies, were shown to be effective as soil/sediment amendments to diminish bioavailability of PCDD/Fs.
Current risk assessment models typically assume 100% bioavailability of PCDD/Fs in soils. The ability to assign scientifically informed values for PCDD/F bioavailability, that account for soil composition, represents a major advance in understanding the exposure risk of PCDD/F contaminated soils/sediments. Formulating safe and realistic remediation endpoints based on available contaminant concentrations instead of total ones allows limited remediation funds to be better prioritized and needless remediation attempts avoided.
|Nault, Rance; Doskey, Claire M; Fader, Kelly A et al. (2018) Comparison of Hepatic NRF2 and Aryl Hydrocarbon Receptor Binding in 2,3,7,8-Tetrachlorodibenzo-p-dioxin-Treated Mice Demonstrates NRF2-Independent PKM2 Induction. Mol Pharmacol 94:876-884|
|Dornbos, Peter; LaPres, John J (2018) Incorporating population-level genetic variability within laboratory models in toxicology: From the individual to the population. Toxicology 395:1-8|
|Zhang, Shuai; Liu, Qinfu; Gao, Feng et al. (2018) Interfacial Structure and Interaction of Kaolinite Intercalated with N-methylformamide Insight from Molecular Dynamics Modeling. Appl Clay Sci 158:204-210|
|Fader, Kelly A; Nault, Rance; Raehtz, Sandi et al. (2018) 2,3,7,8-Tetrachlorodibenzo-p-dioxin dose-dependently increases bone mass and decreases marrow adiposity in juvenile mice. Toxicol Appl Pharmacol 348:85-98|
|Zhang, Shuai; Liu, Qinfu; Cheng, Hongfei et al. (2018) Mechanism Responsible for Intercalation of Dimethyl Sulfoxide in Kaolinite: Molecular Dynamics Simulations. Appl Clay Sci 151:46-53|
|Zhang, Qiang; Li, Jin; Middleton, Alistair et al. (2018) Bridging the Data Gap From in vitro Toxicity Testing to Chemical Safety Assessment Through Computational Modeling. Front Public Health 6:261|
|Fader, K A; Nault, R; Kirby, M P et al. (2018) Corrigendum to ""Convergence of hepcidin deficiency, systemic iron overloading, heme accumulation, and REV-ERB?/? activation in aryl hydrocarbon receptor-elicited hepatotoxicity"" [Toxicol. Appl. Pharmacol. 321 (2017) 1-17]. Toxicol Appl Pharmacol 344:74|
|Konganti, Kranti; Ehrlich, Andre; Rusyn, Ivan et al. (2018) gQTL: A Web Application for QTL Analysis Using the Collaborative Cross Mouse Genetic Reference Population. G3 (Bethesda) 8:2559-2562|
|Zhang, Shuai; Liu, Qinfu; Gao, Feng et al. (2018) Molecular Dynamics Simulation of Basal Spacing, Energetics, and Structure Evolution of a Kaolinite-Formamide Intercalation Complex and Their Interfacial Interaction. J Phys Chem C Nanomater Interfaces 122:3341-3349|
|Williams, M R; Stedtfeld, R D; Waseem, H et al. (2017) Implications of direct amplification for measuring antimicrobial resistance using point-of-care devices. Anal Methods 9:1229-1241|
Showing the most recent 10 out of 417 publications