The effect of ageing on the bioaccessibility and fractionation of cadmium in some typical soils of China

Tang, Xiangyu; Zhu, Yan; Cui, Yanshan; Duan, Jing; Tang, Lily

doi:10.1016/j.envint.2006.03.003

Cited by 146 publications

(71 citation statements)

References 49 publications

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“…This can also be seen in the very high uncertainty in the in vivo measurements (Figures 5(a) to 5(d)). Variability in bioaccessible As can be reduced by careful control of in vitro pH which has been shown to greatly affect the measured metal bioaccessibility (Oomen et al, 2002;Yang et al, 2003;Waisberg et al, 2004;Tang et al, 2006;Tang et al, 2007;Tang et al, 2008).…”

Section: Discussionmentioning

confidence: 99%

An inter-laboratory trial of the unified BARGE bioaccessibility method for arsenic, cadmium and lead in soil

Wragg

Cave

Basta

et al. 2011

Science of The Total Environment

166

202

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The Bioaccessibility Research Group of Europe (BARGE) has carried out an interlaboratory trial of a proposed harmonised in vitro physiologically based ingestion bioaccessibility procedure for soils, called the Unified BARGE Method (UBM). The UBM includes an initial saliva phase and simulated stomach and intestine compartments. The trial involved the participation of seven laboratories (five European and two North American) providing bioaccessibility data for As (11 samples), Cd (9 samples) and Pb (13 samples) using soils with in vivo relative bioavailability data measured using a swine model. The results of the study were compared with benchmark criteria for assessing the suitability of the UBM to provide data for human health risk assessments. Mine waste and slag soils containing high concentrations of As caused problems of poor repeatability and reproducibility which were alleviated when the samples were run at lower soil to solution ratios. The study showed that the UBM met the benchmark criteria for both the stomach and stomach & intestine phase for As. For Cd, three out of four criteria were met for the stomach phase but only one for the stomach & intestine phase. For Pb two, out of four criteria were met for the stomach phase and none for the stomach & intestine phase. However, the study recommends tighter control of pH in the stomach phase extraction to improve between-laboratory variability, more reproducible in vivo validation data and that a follow up inter-laboratory trial should be carried out.

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Section: Discussionmentioning

confidence: 99%

An inter-laboratory trial of the unified BARGE bioaccessibility method for arsenic, cadmium and lead in soil

Wragg

Cave

Basta

et al. 2011

Science of The Total Environment

166

202

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“…Full details of the in vitro test procedure are described in Tang et al (2006); only brief details are given here. The test, including the gastric (pH 1.5, 1 h, 37°C) and small intestinal phases (pH 7, 4 h, 37°C), was conducted with 6 g of soil in 600 ml of synthetic digestive juice (mainly composed of NaCl, organic acids, and enzymes) under anaerobic conditions.…”

Section: Procedures For the Physiologically Based In Vitro Testmentioning

confidence: 99%

The ageing effect on the bioaccessibility and fractionation of arsenic in soils from China

et al. 2007

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Ingestion of contaminated soil has been recognized as an important exposure pathway of arsenic for humans, especially for children through outdoor hand-to-mouth activities. An improved sequential extraction procedure was employed in an attempt to reveal the relationship between bioaccessibility and fractionation of As in five soils from China. Arsenic bioaccessibility in acidic (%pH 4.5) soils reached approximately stable levels after a sharp decline within one week of ageing. In contrast, As bioaccessibility in higher pH (>6.0) soils was found to be significantly higher and took two weeks of ageing to reach stable levels. The artificially added As was more labile than indigenous As. The main proportions of added As were found in the specifically sorbed and amorphous and poorly-crystalline hydrous Fe/Al oxide-bound fractions. Correlation analysis shows that the non-specifically and specifically sorbed As are likely to constitute the main proportion of bioaccessible soil As. The soil content of amorphous and crystalline Fe/Al oxides and soil pH appear to be the key factors controlling, not only the time needed to reach a steady state, but also the magnitude of the bioaccessibility of As added to the soils.

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“…The bioaccessibility of soil As from five soils was investigated using the PBET method (small intestinal phase) combined with the SHIME model (colon phase). The PBET method was modified 8,33 from the procedure described by Ruby et al 9 In brief, soils (0.3 g) were added to polypropylene conical centrifuge tubes (50 mL) with the gastric and small intestinal solutions (30 mL) at a soil/ solution (s/s) ratio of 1:100. Following the small intestinal phase, these digests were transferred into 100 mL anaerobic serum bottles with 30 mL of colon solution from the descending colon compartment of the dynamic SHIME system at a ratio (s/s) of 1:200.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

In Vitro Method To Assess Soil Arsenic Metabolism by Human Gut Microbiota: Arsenic Speciation and Distribution

Yin

Zhang

Cai

et al. 2015

Environ. Sci. Technol.

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Arsenic (As) speciation and distribution are two important factors in assessing human health risk from As-contaminated soil. In this study, we used the combination of physiologically based extraction test (PBET) and Simulator of Human Intestinal Microbial Ecosystem (SHIME) to determine soil As metabolism by human gut microbiota. The results showed that the percentage of soil arsenate [As(V)] transformation reached 22.1−38.2%, while that of arsenite [As(III)] attained 66.5−92.0%; 30.1−56.4% of As(V) transformed was attached to the soil solid phase. In comparison to sequential extraction results, almost all amorphous Fe/Al-oxide-bound As was liberated in the colon phase. An X-ray absorption nearedge structure (XANES) showed that the As(III) percentage in the soil solid phase reached 16.6−26.9% and reached 73.4% (soil 1) in the colon phase. Additionally, plenty of As(III) and different extents of methylation were also observed in colon extraction solution. As bioaccessibility in the colon phase was 1.8−2.8 times that in the small intestinal phase. Our results indicated that human gut microbiota increased As bioaccessibility, and large amounts of As(III) were adsorbed onto the soil solid phase as a result of microbial reduction. Determining As speciation and distribution in extraction solution and soil solid phases will allow for an accurate assessment of the risk to human health upon soil As exposure. ■ INTRODUCTIONArsenic (As) is a common toxic contaminant that is extensively distributed in the environment. 1 Human exposure to As in soils is a major public concern and is associated with serious risks to human health because As species are known carcinogens. 2,3 In most cases, human exposure to soil As occurs via inhalation, inadvertent oral ingestion, and dermal contact. 4,5 Inadvertent oral ingestion has been considered an important exposure route for soil As, especially ingestion through outdoor hand-to-mouth activities by children. 6 The estimation of As bioaccessibility (gastric and small intestinal phases) in contaminated soils through in vitro methods has been used for human health risk assessment. On the basis of previous studies, 7−9 simple, fast, and inexpensive in vitro methods can effectively estimate in vivo relative As bioavailability. Generally, bioaccessibility is defined as the fraction of As that is soluble in the gastrointestinal environment of humans and available for absorption, whereas bioavailability is determined by the fraction of As that is absorbed into the systemic circulation. 7,8 Currently, As bioaccessibility in the gastric and small intestinal phases may underestimate its harm to human health. 10 Studies have clearly illustrated that gut microbiota significantly affect As metabolism by, for example, reduction, methylation, and thiolation. 11 As metabolism in contaminated soil by human gut microbiota can affect As bioaccessibility and speciation. 10,12 Therefore, As biotransformation must be considered an essential part of the risk assessment of oral soil As exposure using i...

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The effect of ageing on the bioaccessibility and fractionation of cadmium in some typical soils of China

Cited by 146 publications

References 49 publications

An inter-laboratory trial of the unified BARGE bioaccessibility method for arsenic, cadmium and lead in soil

An inter-laboratory trial of the unified BARGE bioaccessibility method for arsenic, cadmium and lead in soil

The ageing effect on the bioaccessibility and fractionation of arsenic in soils from China

In Vitro Method To Assess Soil Arsenic Metabolism by Human Gut Microbiota: Arsenic Speciation and Distribution

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