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Luchun Duan
Global Centre for Environmental Remediation (GCER), Faculty of Science, The University of Newcastle, University Drive, Callaghan, NSW 2308, Australia

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Journal article
Published: 27 July 2020 in Environmental Technology & Innovation
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Diuron is one of the most common herbicides used in agriculture with long persistence and high toxicity causing a certain hazard to the environment. Thus, this is necessary to control the residue levels of diuron in a natural environment. To achieve this goal, a diffusive gradient in thin-films technique (DGT), as a new method for in-situ sampling, is described in this paper, which can provide the time-weighted average concentration of target compounds in the sampling period. DGT consists of XAD18 resin gel can accumulate up to 73.58 ug diuron in lab conditions and without significant negative performance under varies range of pH (4 to 9), ionic strength (0.001 to 0.5 mmol L−1) and dissolved organic matter(0 – 20 mg L−1). The string rate of more than 100 rpm indicated the DGT will not likely be affected by flow rate in the aquatic environment. The study successfully indicates the DGT’s performance on diuron, providing a promising technique for future investigation of distribution and occurrence in the natural environment.

ACS Style

Qiushi Duan; Luchun Duan; Yanju Liu; Ravi Naidu; Hao Zhang; Yongjia Lei. A novel in-situ passive sampling technique in the application of monitoring diuron in the aquatic environment. Environmental Technology & Innovation 2020, 20, 101073 .

AMA Style

Qiushi Duan, Luchun Duan, Yanju Liu, Ravi Naidu, Hao Zhang, Yongjia Lei. A novel in-situ passive sampling technique in the application of monitoring diuron in the aquatic environment. Environmental Technology & Innovation. 2020; 20 ():101073.

Chicago/Turabian Style

Qiushi Duan; Luchun Duan; Yanju Liu; Ravi Naidu; Hao Zhang; Yongjia Lei. 2020. "A novel in-situ passive sampling technique in the application of monitoring diuron in the aquatic environment." Environmental Technology & Innovation 20, no. : 101073.

Journal article
Published: 27 June 2019 in Science of The Total Environment
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Higher soil pH and electrical conductivity (EC) were suspected to result in higher extractability and bioavailability of benzo[a]pyrene (B[a]P) in soils. In this study, we investigated the influence of pH, EC and ageing on the extractability of B[a]P in two contracting soils (varied largely in soil texture, clay mineralogy and organic carbon content) over 4 months. Dilute sodium hydroxide (0.2 mol L−1) and sodium chloride (0.1 mol L−1) solutions were used to adjust soil pH and EC either separately or simultaneously. Extractability of B[a]P in these soils was monitored using a mild solvent extraction using butanol (BuOH, end-over-end shake over 24 h), and an exhaustive mix-solvent extraction using dichloromethane/acetone (DCM/Ace, v:v = 1:1) facilitated by sonication and a subsequent NaOH saponification method following the DCM/Ace extraction. Results showed that increased pH and/or EC significantly increased the B[a]P extractability in the sandy soil (GIA). Variance analysis of contribution of pH and/or EC modification and ageing time on changes in B[a]P extractability indicated that in GIA > 55% and over 25% of the changes in B[a]P extractability was attributed to increased pH&EC and pH only respectively. While ageing resulted in >85% of the change in B[a]P extractability in the clayey soil (BDA), following by increased pH&EC (contribution < 15%). Large amount of non-extractable residue (NER) were formed over the ageing period, up to 95% and 79% in GIA/BDA and its modified soils, respectively. Significant correlations were observed between B[a]P BuOH extractability and the exhaustive sequential extraction using DCM/Ace followed by NaOH saponification for all soils (p < 0.001). With slopes of the correlations close to 1, our results indicated that the simple mild solvent BuOH extraction was equivalent to the complex sequential DCM/Ace and NaOH saponification extraction in these soils.

ACS Style

Fanbo Meng; Xiaodong Yang; Luchun Duan; Ravi Naidu; Nuruzzaman; Kirk Semple. Influence of pH, electrical conductivity and ageing on the extractability of benzo[a]pyrene in two contrasting soils. Science of The Total Environment 2019, 690, 647 -653.

AMA Style

Fanbo Meng, Xiaodong Yang, Luchun Duan, Ravi Naidu, Nuruzzaman, Kirk Semple. Influence of pH, electrical conductivity and ageing on the extractability of benzo[a]pyrene in two contrasting soils. Science of The Total Environment. 2019; 690 ():647-653.

Chicago/Turabian Style

Fanbo Meng; Xiaodong Yang; Luchun Duan; Ravi Naidu; Nuruzzaman; Kirk Semple. 2019. "Influence of pH, electrical conductivity and ageing on the extractability of benzo[a]pyrene in two contrasting soils." Science of The Total Environment 690, no. : 647-653.

Research article
Published: 16 October 2018 in Environmental Science & Technology
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The environmental and health risks associated with “nonextractable” residues (NERs) of polycyclic aromatic hydrocarbons in soils and their potential for remobilization remain largely unexplored. In this novel study, sequential solvent extractions were employed to interrogate time-dependent remobilization of benzo[a]pyrene (B[a]P) NERs and associated kinetics after re-equilibration (REQ) periods lasting 30 d in four artificially spiked soils aged for up to 200 days. Following sequential extractions of the re-equilibrated soils, remobilization of B[a]P NERs was observed and further confirmed by decreases in the absolute amounts of B[a]P recovered following methanolic saponification after REQ. Remobilization may occur through slow intercompartmental partitioning of more sequestered into less sequestered B[a]P fractions in soils. The amounts of B[a]P remobilized in soils decreased throughout aging following first-order kinetics, and the rates of decrease were slow but 2 to 4 times faster than those of extractable B[a]P before re-equilibration. Sandy-clay-loam soils with large amounts of hard organic carbon exhibited less NER remobilization compared to sandy soils. The amounts of remobilized B[a]P decreased significantly (p < 0.05) with aging. Specifically, butanol-remobilized B[a]P in soils spiked at 10 mg/kg and 50 mg/kg B[a]P ranged from 0.15 to 0.39 mg/kg and 0.67 to 2.30 mg/kg, respectively, after 200 d of aging.

ACS Style

Anthony C. Umeh; Luchun Duan; Ravi Naidu; Kirk T. Semple. Time-Dependent Remobilization of Nonextractable Benzo[a]pyrene Residues in Contrasting Soils: Effects of Aging, Spiked Concentration, and Soil Properties. Environmental Science & Technology 2018, 52, 12295 -12305.

AMA Style

Anthony C. Umeh, Luchun Duan, Ravi Naidu, Kirk T. Semple. Time-Dependent Remobilization of Nonextractable Benzo[a]pyrene Residues in Contrasting Soils: Effects of Aging, Spiked Concentration, and Soil Properties. Environmental Science & Technology. 2018; 52 (21):12295-12305.

Chicago/Turabian Style

Anthony C. Umeh; Luchun Duan; Ravi Naidu; Kirk T. Semple. 2018. "Time-Dependent Remobilization of Nonextractable Benzo[a]pyrene Residues in Contrasting Soils: Effects of Aging, Spiked Concentration, and Soil Properties." Environmental Science & Technology 52, no. 21: 12295-12305.

Research article
Published: 29 September 2018 in Analytical Chemistry
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The fate, impacts and significance of polycyclic aromatic hydrocarbon (PAH) non-extractable residues (NERs) in soils remain largely unexplored in risk-based contaminated land management. In this study, 7 different methanolic and non-methanolic alkaline treatments, and the conventional methanolic saponification, were used to extract benzo[a]pyrene (B[a]P) NERs that had been aged for 180 d from four contrasting soils. Up to 16% and 55% of the amount of B[a]P spiked (50 mg/kg) into soils was non-extractable after 2 d and 180 of aging, respectively; indicating rapid and progressive B[a]P sequestration in soils over time. The recovery of B[a]P from soils after 180 d of aging was increased by up to 48% by the 7 different alkaline extractions, although the extraction efficiencies of the different alkaline treatments did not differ significantly (p > 0.05). Approximately 40% of B[a]P NERs in the sandy-clay-loam organic matter-rich soil was recovered by the exhaustive alkaline extractions after 180 d of aging, compared to only 10% using conventional methanolic saponification. However, the amounts of B[a]P NERs recovered depend on soil properties and the amounts of NERs in soils. A significant correlation (R2 = 0.69, p < 0.001) was also observed between the amounts of B[a]P recovered by each of the 7 alkaline extractions in the contrasting soils, and corresponding NERs at 180 d of aging, indicating a potential association warranting further investigations. Extraction techniques that estimate the amounts of PAH NERs recoverable in soil can help give a better understanding of the fate of NERs in soil.

ACS Style

Anthony C. Umeh; Luchun Duan; Ravi Naidu; Kirk T. Semple. Enhanced Recovery of Nonextractable Benzo[a]pyrene Residues in Contrasting Soils Using Exhaustive Methanolic and Nonmethanolic Alkaline Treatments. Analytical Chemistry 2018, 90, 13104 -13111.

AMA Style

Anthony C. Umeh, Luchun Duan, Ravi Naidu, Kirk T. Semple. Enhanced Recovery of Nonextractable Benzo[a]pyrene Residues in Contrasting Soils Using Exhaustive Methanolic and Nonmethanolic Alkaline Treatments. Analytical Chemistry. 2018; 90 (21):13104-13111.

Chicago/Turabian Style

Anthony C. Umeh; Luchun Duan; Ravi Naidu; Kirk T. Semple. 2018. "Enhanced Recovery of Nonextractable Benzo[a]pyrene Residues in Contrasting Soils Using Exhaustive Methanolic and Nonmethanolic Alkaline Treatments." Analytical Chemistry 90, no. 21: 13104-13111.

Research article
Published: 23 August 2018 in Analytical Chemistry
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The fate and behavior of polycyclic aromatic hydrocarbons (PAHs) in soil are of interest in the risk assessment of contaminated land and are usually based on determinations of fractions extracted from soil. For decades, either single- or sequential-solvent extractions have been used to determine PAH extractability in soils; however, there is a lack of certainty as to which fractions are being extracted by these techniques. This study is the first report of differences and similarities in the extractability of benzo[a]pyrene (B[a]P) in four contrasting soils (sandy loam, loamy sand, clayey loam, and sandy) when determined using both single-solvent (dichloromethane/acetone (DCM/Ace) mixture) and sequential-solvent (butanol followed by DCM/Ace) extraction. Residues after extraction were subjected to methanolic saponification (MeKOH). Butanol (BuOH) extractability and total extractability of B[a]P following sequential-solvent extraction decreased significantly (p < 0.05) with time after addition of B[a]P. The decrease in BuOH extractability was particularly marked in the organic-matter-rich clayey-loam soil, which also had the largest (>40%) amounts of nonextractable residues. The cumulative amounts of B[a]P extracted in each soil by single- and sequential-solvent extractions were similar (p > 0.05) at each aging period, which indicated access to similar B[a]P fractions in soil by both solvent extractions. The similarities in the amounts of B[a]P nonextractable residues recovered by MeKOH from pre-extracted soils, through either of the extraction methods, confirms that the total extractable B[a]P fractions from both methods are similar.

ACS Style

Anthony C. Umeh; Luchun Duan; Ravi Naidu; Kirk T. Semple. Comparison of Single- and Sequential-Solvent Extractions of Total Extractable Benzo[a]pyrene Fractions in Contrasting Soils. Analytical Chemistry 2018, 90, 11703 -11709.

AMA Style

Anthony C. Umeh, Luchun Duan, Ravi Naidu, Kirk T. Semple. Comparison of Single- and Sequential-Solvent Extractions of Total Extractable Benzo[a]pyrene Fractions in Contrasting Soils. Analytical Chemistry. 2018; 90 (19):11703-11709.

Chicago/Turabian Style

Anthony C. Umeh; Luchun Duan; Ravi Naidu; Kirk T. Semple. 2018. "Comparison of Single- and Sequential-Solvent Extractions of Total Extractable Benzo[a]pyrene Fractions in Contrasting Soils." Analytical Chemistry 90, no. 19: 11703-11709.

Journal article
Published: 30 April 2018 in International Journal of Environmental Research and Public Health
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Chronic exposure to arsenic (As) is a global concern due to worldwide exposure and adverse effects, and the importance of incorporating bioavailability in the exposure assessment and risk assessment of As is increasing acknowledged. The bioavailability of As is impacted by a number of soil properties, such as pH, clay and metal concentrations. By retrieving 485 data from 32 publications, the aim of this study was to determine the relationship between selected metals (Fe and Al) and As bioavailability. In present study, the bioaccessibility (BAC) data measured by in vitro approaches were converted into bioavailability data based on the previously determined relationship between BAC and bioavailability. The As relative bioavailability (RBA) was summarized to be 24.36 ± 18.49%, which is in the range previously reported. A significant association between Fe concentration and the bioavailability of As was observed while this association varied for different types of RBA data. This disparity may suggest a non-reliable association between Fe and As bioavailability. The correlations between logarithmically transformed total content of Fe + Al and As bioavailability is then outlined: RBA = (−8.40 ± 1.02) × Ln(Fe + Al) + (58.25 ± 4.09), R² = 0.25, p < 0.001, n = 212. Jackknife resampling was also applied to validate the relation between total content of (Fe + Al) and As bioavailability, which suggested that the relation is robust. This is the first pooled study to address the relations between selected metal concentrations and As bioavailability, which may provide some implications to establish soil properties-based RBA prediction for As.

ACS Style

Kaihong Yan; Ravi Naidu; Yanju Liu; Ayanka Wijayawardena; Luchun Duan; Zhaomin Dong. A Pooled Data Analysis to Determine the Relationship between Selected Metals and Arsenic Bioavailability in Soil. International Journal of Environmental Research and Public Health 2018, 15, 888 .

AMA Style

Kaihong Yan, Ravi Naidu, Yanju Liu, Ayanka Wijayawardena, Luchun Duan, Zhaomin Dong. A Pooled Data Analysis to Determine the Relationship between Selected Metals and Arsenic Bioavailability in Soil. International Journal of Environmental Research and Public Health. 2018; 15 (5):888.

Chicago/Turabian Style

Kaihong Yan; Ravi Naidu; Yanju Liu; Ayanka Wijayawardena; Luchun Duan; Zhaomin Dong. 2018. "A Pooled Data Analysis to Determine the Relationship between Selected Metals and Arsenic Bioavailability in Soil." International Journal of Environmental Research and Public Health 15, no. 5: 888.

Review
Published: 01 February 2018 in Science of The Total Environment
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The bioavailability and bioaccessibility of polycyclic aromatic hydrocarbons (PAHs) in soil underpin the risk assessment of contaminated land with these contaminants. Despite a significant volume of research conducted in the past few decades, comprehensive understanding of the factors controlling the behaviour of soil PAHs and a set of descriptive soil parameters to explain variations in PAH bioavailability and bioaccessibility are still lacking. This review focuses on the role of source materials on bioavailability and bioaccessibility of soil PAHs, which is often overlooked, along with other abiotic factors including contaminant concentration and mixture, soil composition and properties, as well as environmental factors. It also takes into consideration the implications of different types of risk assessment (ecological and human health) on bioavailability and bioaccessibility of PAHs in soil. We recommend that future research should (1) account for the effects of source materials on bioavailability and bioaccessibility of soil PAHs; (2) adopt non-disruptive methods to analyse soil components controlling PAH sequestration; (3) integrate both natural organic matter (NOM) and xenobiotic organic matter (XOM) while evaluating the influences of soil organic matter (SOM) on the behaviour of PAHs; and (4) consider the dissimilar desorption scenarios in ecological risk assessment and human health risk assessment while assessing PAH bioavailability and bioaccessibility.

ACS Style

Linbo Yu; Luchun Duan; Ravi Naidu; Kirk Semple. Abiotic factors controlling bioavailability and bioaccessibility of polycyclic aromatic hydrocarbons in soil: Putting together a bigger picture. Science of The Total Environment 2018, 613-614, 1140 -1153.

AMA Style

Linbo Yu, Luchun Duan, Ravi Naidu, Kirk Semple. Abiotic factors controlling bioavailability and bioaccessibility of polycyclic aromatic hydrocarbons in soil: Putting together a bigger picture. Science of The Total Environment. 2018; 613-614 ():1140-1153.

Chicago/Turabian Style

Linbo Yu; Luchun Duan; Ravi Naidu; Kirk Semple. 2018. "Abiotic factors controlling bioavailability and bioaccessibility of polycyclic aromatic hydrocarbons in soil: Putting together a bigger picture." Science of The Total Environment 613-614, no. : 1140-1153.

Journal article
Published: 01 December 2017 in Science of The Total Environment
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An in vivo assay using swine was used to measure the absolute bioavailability (AB) of As from cooked rice of twelve genotypes commonly grown in Bangladesh. An assessment of both total As in rice and its bioavailability is crucial for estimating human exposure following dietary intake by the local community. Average As concentrations in each rice genotype ranged from 108±4μg/kg to 580±6μg/kg. Arsenic speciation shows that most of the rice genotype contains 73 to 100% inorganic As. Swine were administered with As orally and via intravenous method, i.e. injection and fed certain common Bangladeshi rice genotypes (cooked). Swine blood As levels were measured to calculate As bioavailability from rice. Pilot studies shows that for As(III) and As(V), 90.8±12.4% and 85.0±19.2% of the administered oral dose was absorbed from the gastrointestinal tract whereas organic As was poorly absorbed resulting in low bioavailability values 20.2±2.6% (MMA) to 31.2±3.4% (DMA), respectively. These studies demonstrates that rice genotypic characters influenced As bioavailability in rice grown in As-contaminated areas and the bioavailability varied between 25% and 94%. Arsenic in salt tolerant rice genotypes Binadhan-10 and BRRI dhan47 as well as brown rice genotypes Kheali Boro and Local Boro has lower bioavailability (<50%) compared to other rice genotypes. The most commonly cultivated and consumed variety (BRRI dhan28) has As bioavailability of 70%, which poses a significant risk to consumers. Calculation of maximum tolerable daily intake (MTDI) for humans due to consumption of rice based on bioavailability data was higher than those calculated based on inorganic and organic As concentration in rice genotypes.

ACS Style

Shofiqul Islam; Mohammad Mahmudur Rahman; Luchun Duan; M.R. Islam; Tim Kuchel; Ravi Naidu. Variation in arsenic bioavailability in rice genotypes using swine model: An animal study. Science of The Total Environment 2017, 599-600, 324 -331.

AMA Style

Shofiqul Islam, Mohammad Mahmudur Rahman, Luchun Duan, M.R. Islam, Tim Kuchel, Ravi Naidu. Variation in arsenic bioavailability in rice genotypes using swine model: An animal study. Science of The Total Environment. 2017; 599-600 ():324-331.

Chicago/Turabian Style

Shofiqul Islam; Mohammad Mahmudur Rahman; Luchun Duan; M.R. Islam; Tim Kuchel; Ravi Naidu. 2017. "Variation in arsenic bioavailability in rice genotypes using swine model: An animal study." Science of The Total Environment 599-600, no. : 324-331.

Journal article
Published: 01 August 2017 in Environment International
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On 25th May 2016, the U.S. EPA released reference doses (RfDs) for Perfluorooctane Sulfonate (PFOS) and Perfluorooctanoic Acid (PFOA) of 20ng/kg/day, which were much more conservative than previous values. These RfDs rely on the choices of animal point of departure (PoD) and the toxicokinetics (TK) model. At this stage, considering that the human evidence is not strong enough for RfD determination, using animal data may be appropriate but with more uncertainties. In this article, the uncertainties concerning RfDs from the choices of PoD and TK models are addressed. Firstly, the candidate PoDs should include more critical endpoints (such as immunotoxicity), which may lead to lower RfDs. Secondly, the reliability of the adopted three-compartment TK model is compromised: the parameters are not non-biologically plausible; and this TK model was applied to simulate gestation and lactation exposures, while the two exposure scenarios were not actually included in the model structure.

ACS Style

Zhaomin Dong; Mezbaul Bahar; Joytishna Jit; Bruce Kennedy; Brian Priestly; Jack Ng; Dane Lamb; Yanju Liu; Luchun Duan; Ravi Naidu. Issues raised by the reference doses for perfluorooctane sulfonate and perfluorooctanoic acid. Environment International 2017, 105, 86 -94.

AMA Style

Zhaomin Dong, Mezbaul Bahar, Joytishna Jit, Bruce Kennedy, Brian Priestly, Jack Ng, Dane Lamb, Yanju Liu, Luchun Duan, Ravi Naidu. Issues raised by the reference doses for perfluorooctane sulfonate and perfluorooctanoic acid. Environment International. 2017; 105 ():86-94.

Chicago/Turabian Style

Zhaomin Dong; Mezbaul Bahar; Joytishna Jit; Bruce Kennedy; Brian Priestly; Jack Ng; Dane Lamb; Yanju Liu; Luchun Duan; Ravi Naidu. 2017. "Issues raised by the reference doses for perfluorooctane sulfonate and perfluorooctanoic acid." Environment International 105, no. : 86-94.

Review
Published: 01 January 2017 in Environment International
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Risk-based approaches to managing contaminated land, rather than approaches based on complete contaminant removal, have gained acceptance as they are likely to be more feasible and cost effective. Risk-based approaches aim to minimise risks of exposure of a specified contaminant to humans. However, adopting a risk-based approach over alternative overly-conservative approaches requires that associated uncertainties in decision making are understood and minimised. Irrespective of the nature of contaminants, a critical uncertainty is whether there are potential risks associated with exposure to the residual contaminant fractions in soil to humans and other ecological receptors, and how they should be considered in the risk assessment process. This review focusing on hydrophobic organic contaminants (HOCs), especially polycyclic aromatic hydrocarbons (PAHs), suggests that there is significant uncertainty on the residual fractions of contaminants from risk perspectives. This is because very few studies have focused on understanding the desorption behaviour of HOCs, with few or no studies considering the influence of exposure-specific factors. In particular, it is not clear whether the exposure of soil-associated HOCs to gastrointestinal fluids and enzyme processes release bound residues. Although, in vitro models have been used to predict PAH bioaccessibility, and chemical extractions have been used to determine residual fractions in various soils, there are still doubts about what is actually being measured. Therefore it is not certain which bioaccessibility method currently represents the best choice, or provides the best estimate, of in vivo PAH bioavailability. It is suggested that the fate and behaviour of HOCs in a wide range of soils, and that consider exposure-specific scenarios, be investigated. Exposure-specific scenarios are important for validation purposes, which may be useful for the development of standardised methods and procedures for HOC bioaccessibility determinations. Research is needed to propose the most appropriate testing methods and for assessing potential risks posed by residual fractions of HOCs. Such investigations may be useful for minimising uncertainties associated with a risk-based approach, so that consideration may then be given to its adoption on a global scale. This review critically appraises existing information on the bioavailability of HOC residues in soil to establish whether there may be risks from highly sequestered contaminant residues

ACS Style

Anthony Umeh; Luchun Duan; Ravi Naidu; Kirk Semple. Residual hydrophobic organic contaminants in soil: Are they a barrier to risk-based approaches for managing contaminated land? Environment International 2017, 98, 18 -34.

AMA Style

Anthony Umeh, Luchun Duan, Ravi Naidu, Kirk Semple. Residual hydrophobic organic contaminants in soil: Are they a barrier to risk-based approaches for managing contaminated land? Environment International. 2017; 98 ():18-34.

Chicago/Turabian Style

Anthony Umeh; Luchun Duan; Ravi Naidu; Kirk Semple. 2017. "Residual hydrophobic organic contaminants in soil: Are they a barrier to risk-based approaches for managing contaminated land?" Environment International 98, no. : 18-34.

Journal article
Published: 01 September 2016 in Environment International
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There are many uncertainties concerning variations in benzo[a]pyrene (B[a]P) soil guidelines protecting human health based on carcinogenic data obtained in animal studies. Although swine is recognised as being much more representative of the human child in terms of body size, gut physiology and genetic profile the rat/mice model is commonly used in practice. We compare B[a]P bioavailability using a rat model to that estimated in a swine model, to investigate the correlation between these two animal models. This may help reduce uncertainty in applying bioavailability to human health risk assessment. Twelve spiked soil samples and a spiked silica sand (reference material) were dosed to rats in parallel with a swine study. B[a]P bioavailability was estimated by the area under the plasma B[a]P concentration-time curve (AUC) and faecal excretion as well in the rats. Direct comparison between the two animal models was made for: firstly, relative bioavailability (RB) using AUC assay; and secondly, the two assays in the rat model. Both AUC and faecal excretion assays showed linear dose-response for the reference material. However, absolute bioavailability was significantly higher when using faecal excretion assay (p < 0.001). In aged soils faecal excretion estimated based on solvent extraction was not accurate due to the form of non-extractable fraction through ageing. A significant correlation existed between the two models using RB for soil samples (RBrat = 0.26RBswine + 17.3, R2 = 0.70, p < 0.001), despite the regression slope coefficient revealing that the rat model would underestimate RB by about one quarter compared to using swine. In the comparison employed in this study, an interspecies difference of four in RB using AUC assay was identified between the rat and swine models regarding pharmacokinetic differences, which supported the body weight scaling method recommended by US EPA. Future research should focus on the carcinogenic competency (pharmacodynamics) used in experiment animals and humans.

ACS Style

Luchun Duan; Ravi Naidu; Yanju Liu; Zhaomin Dong; Megharaj Mallavarapu; Paul Herde; Tim Kuchel; Kirk Semple. Comparison of oral bioavailability of benzo[ a ]pyrene in soils using rat and swine and the implications for human health risk assessment. Environment International 2016, 94, 95 -102.

AMA Style

Luchun Duan, Ravi Naidu, Yanju Liu, Zhaomin Dong, Megharaj Mallavarapu, Paul Herde, Tim Kuchel, Kirk Semple. Comparison of oral bioavailability of benzo[ a ]pyrene in soils using rat and swine and the implications for human health risk assessment. Environment International. 2016; 94 ():95-102.

Chicago/Turabian Style

Luchun Duan; Ravi Naidu; Yanju Liu; Zhaomin Dong; Megharaj Mallavarapu; Paul Herde; Tim Kuchel; Kirk Semple. 2016. "Comparison of oral bioavailability of benzo[ a ]pyrene in soils using rat and swine and the implications for human health risk assessment." Environment International 94, no. : 95-102.

Review
Published: 01 July 2016 in Environment International
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Defining the precise clean-up goals for lead (Pb) contaminated sites requires site-specific information on relative bioavailability data (RBA). While in vivo measurement is reliable but resource insensitive, in vitro approaches promise to provide high-throughput RBA predictions. One challenge on using in vitro bioaccessibility (BAc) to predict in vivo RBA is how to minimize the heterogeneities associated with in vivo-in vitro correlations (IVIVCs) stemming from various biomarkers (kidney, blood, liver, urinary and femur), in vitro approaches and studies. In this study, 252 paired RBA-BAc data were retrieved from 9 publications, and then a Bayesian hierarchical model was implemented to address these random effects. A generic linear model (RBA (%)=(0.87±0.16)×BAc+(4.70±2.47)) of the IVIVCs was identified. While the differences of the IVIVCs among the in vitro approaches were significant, the differences among biomarkers were relatively small. The established IVIVCs were then applied to predict Pb RBA of which an overall Pb RBA estimation was 0.49±0.25. In particular the RBA in the residential land was the highest (0.58±0.19), followed by house dust (0.46±0.20) and mining/smelting soils (0.45±0.31). This is a new attempt to: firstly, use a meta-analysis to correlate Pb RBA and BAc; and secondly, estimate Pb RBA in relation to soil types.

ACS Style

Zhaomin Dong; Kaihong Yan; Yanju Liu; Ravi Naidu; Luchun Duan; Ayanka Wijayawardena; Kirk T. Semple; Mohammad Mahmudur Rahman. A meta-analysis to correlate lead bioavailability and bioaccessibility and predict lead bioavailability. Environment International 2016, 92-93, 139 -145.

AMA Style

Zhaomin Dong, Kaihong Yan, Yanju Liu, Ravi Naidu, Luchun Duan, Ayanka Wijayawardena, Kirk T. Semple, Mohammad Mahmudur Rahman. A meta-analysis to correlate lead bioavailability and bioaccessibility and predict lead bioavailability. Environment International. 2016; 92-93 ():139-145.

Chicago/Turabian Style

Zhaomin Dong; Kaihong Yan; Yanju Liu; Ravi Naidu; Luchun Duan; Ayanka Wijayawardena; Kirk T. Semple; Mohammad Mahmudur Rahman. 2016. "A meta-analysis to correlate lead bioavailability and bioaccessibility and predict lead bioavailability." Environment International 92-93, no. : 139-145.

Review
Published: 01 December 2015 in Environment International
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Addressing uncertainties in human health risk assessment is a critical issue when evaluating the effects of contaminants on public health. A range of uncertainties exist through the source-to-outcome continuum, including exposure assessment, hazard and risk characterisation. While various strategies have been applied to characterising uncertainty, classical approaches largely rely on how to maximise the available resources. Expert judgement, defaults and tools for characterising quantitative uncertainty attempt to fill the gap between data and regulation requirements. The experiences of researching 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) illustrated uncertainty sources and how to maximise available information to determine uncertainties, and thereby provide an ‘adequate’ protection to contaminant exposure. As regulatory requirements and recurring issues increase, the assessment of complex scenarios involving a large number of chemicals requires more sophisticated tools. Recent advances in exposure and toxicology science provide a large data set for environmental contaminants and public health. In particular, biomonitoring information, in vitro data streams and computational toxicology are the crucial factors in the NexGen risk assessment, as well as uncertainties minimisation. Although in this review we cannot yet predict how the exposure science and modern toxicology will develop in the long-term, current techniques from emerging science can be integrated to improve decision-making.

ACS Style

Zhaomin Dong; Yanju Liu; Luchun Duan; Dawit Bekele; Ravi Naidu. Uncertainties in human health risk assessment of environmental contaminants: A review and perspective. Environment International 2015, 85, 120 -132.

AMA Style

Zhaomin Dong, Yanju Liu, Luchun Duan, Dawit Bekele, Ravi Naidu. Uncertainties in human health risk assessment of environmental contaminants: A review and perspective. Environment International. 2015; 85 ():120-132.

Chicago/Turabian Style

Zhaomin Dong; Yanju Liu; Luchun Duan; Dawit Bekele; Ravi Naidu. 2015. "Uncertainties in human health risk assessment of environmental contaminants: A review and perspective." Environment International 85, no. : 120-132.

Journal article
Published: 25 March 2015 in Environmental Earth Sciences
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Polycyclic aromatic hydrocarbons (PAHs) in sediments of the Subei Grand Canal (SGC) are thought to have a significant effect on the water quality of the South to North Water Transfer Project in China. The SGC is in Jiangsu Province and is the northern section of the Beijing-Hangzhou Grand Canal; it is also part of the eastern route of the South to North Water Transfer Project. In the present study, 37 surface sediment samples were collected from the SGC and were analyzed by high performance liquid chromatography (HPLC) for their PAH concentration. The total PAH concentration in surface sediments was moderate, and ranged from 634 to 14,703 ng/g (dry weight), with a mean of 5239 ng/g. There was significant spatial variation in the total PAH concentrations; for example, the mean concentrations in the Xuzhou area, Huaian-Suqian area, and Yangzhou area were 9708, 3872 and 2376 ng/g, respectively. The organic carbon content (9.4–99.6 mg/g) had an important influence on the PAH concentrations in sediment. Analysis using PAH ratios and PCA indicated that the main sources were coal and wood combustion, vehicular and shipping emissions, and coke ovens. An ecological risk assessment based on biological threshold showed that the PAH in surface sediments of the SGC had the potential to cause adverse biological effects to aquatic organisms, and that these effects were more serious around Xuzhou than in the other areas.

ACS Style

Xi Zheng; Baoping Han; Palanisami Thavamani; Luchun Duan; Ravi Naidu. Composition, source identification and ecological risk assessment of polycyclic aromatic hydrocarbons in surface sediments of the Subei Grand Canal, China. Environmental Earth Sciences 2015, 74, 2669 -2677.

AMA Style

Xi Zheng, Baoping Han, Palanisami Thavamani, Luchun Duan, Ravi Naidu. Composition, source identification and ecological risk assessment of polycyclic aromatic hydrocarbons in surface sediments of the Subei Grand Canal, China. Environmental Earth Sciences. 2015; 74 (3):2669-2677.

Chicago/Turabian Style

Xi Zheng; Baoping Han; Palanisami Thavamani; Luchun Duan; Ravi Naidu. 2015. "Composition, source identification and ecological risk assessment of polycyclic aromatic hydrocarbons in surface sediments of the Subei Grand Canal, China." Environmental Earth Sciences 74, no. 3: 2669-2677.

Journal article
Published: 15 November 2013 in Water, Air, & Soil Pollution
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Sorption characteristics of phenanthrene were studied in batch equilibrium experiments with 32 Australian soils that varied widely in physicochemical properties. Sorption of phenanthrene varied widely among the soils and was generally nonlinear, with the nonlinearity index (n) of the Freundlich isotherm varying from 0.62 to 1.01. Simple regression analyses revealed that total organic carbon (TOC) accounts for about 68 % of the variation in the partition coefficient (K′f ) for sorption among the soils at an equilibrium concentration (C e ) of 0.05 mg/L. The organic carbon normalized distribution coefficient (K OC ), varied considerably between soils with >70 % of the variance of logK OC being accounted for by logTOC, clay and log dissolved organic carbon (DOC). These results show that the phenanthrene C e is influenced by both TOC as well as the DOC in soil suspensions. The effects of ionic strength (IS) and index cation were investigated using four contrasting soils. Results show that with an increase in IS from 0.03 to 0.15 M sorption of phenanthrene generally increased in CaCl2 background solutions, whereas the effect was less significant and variable in NaCl background solutions. Sorption of phenanthrene was slightly higher at low IS (0.03 M) with Na+ as index cation compared with that of Ca2+, whereas an opposite trend was observed at higher IS (0.15 M). For two soils high in TOC, the flocculation of endogenous DOC in the presence of Ca2+ reduced the influence of background electrolyte and resulted in a more linear sorption isotherm as well as higher sorption capacity. This trend was more significant with Ca2+ relative to Na+.

ACS Style

Luchun Duan; Ravi Naidu. Effect of Ionic Strength and Index Cation on the Sorption of Phenanthrene. Water, Air, & Soil Pollution 2013, 224, 1 -17.

AMA Style

Luchun Duan, Ravi Naidu. Effect of Ionic Strength and Index Cation on the Sorption of Phenanthrene. Water, Air, & Soil Pollution. 2013; 224 (12):1-17.

Chicago/Turabian Style

Luchun Duan; Ravi Naidu. 2013. "Effect of Ionic Strength and Index Cation on the Sorption of Phenanthrene." Water, Air, & Soil Pollution 224, no. 12: 1-17.