Bioaccessibility Extractions for Contaminant Risk Assessment

Koch, Iris; Reimer, Ken J.

doi:10.1016/b978-0-12-381373-2.00091-0

Cited by 10 publications

(9 citation statements)

References 184 publications

(235 reference statements)

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“…Several reviews are available (e.g., [6,7] ) and comparative studies between different research groups and methods have focused on one or more of four elements in soils (As, Cd, nickel (Ni) and Pb). [8,9,10,11] To compare methods on a larger scale -within Canada and internationally -and for a larger number of elements, a round-robin study was undertaken to compare soil bioaccessibility data obtained by Canadian and international laboratories using a standard reference material (SRM).…”

Section: Introductionmentioning

confidence: 99%

Variability of bioaccessibility results using seventeen different methods on a standard reference material, NIST 2710

Koch

Reimer

Bakker

et al. 2013

Journal of Environmental Science and Health, Part A

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Bioaccessibility is a measurement of a substance's solubility in the human gastro-intestinal system, and is often used in the risk assessment of soils. The present study was designed to determine the variability among laboratories using different methods to measure the bioaccessibility of 24 inorganic contaminants in one standardized soil sample, the standard reference material NIST 2710. Fourteen laboratories used a total of 17 bioaccessibility extraction methods. The variability between methods was assessed by calculating the reproducibility relative standard deviations (RSDs), where reproducibility is the sum of within-laboratory and between-laboratory variability. Whereas within-laboratory repeatability was usually better than (<) 15% for most elements, reproducibility RSDs were much higher, indicating more variability, although for many elements they were comparable to typical uncertainties (e.g., 30% in commercial laboratories). For five trace elements of interest, reproducibility RSDs were: arsenic (As), 22-44%; cadmium (Cd), 11-41%; Cu, 15-30%; lead (Pb), 45-83%; and Zn, 18-56%. Only one method variable, pH, was found to correlate significantly with bioaccessibility for aluminum (Al), Cd, copper (Cu), manganese (Mn), Pb and zinc (Zn) but other method variables could not be examined systematically because of the study design. When bioaccessibility results were directly compared with bioavailability results for As (swine and mouse) and Pb (swine), four methods returned results within uncertainty ranges for both elements: two that were defined as simpler (gastric phase only, limited chemicals) and two were more complex (gastric + intestinal phases, with a mixture of chemicals).

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Section: Introductionmentioning

confidence: 99%

Variability of bioaccessibility results using seventeen different methods on a standard reference material, NIST 2710

Koch

Reimer

Bakker

et al. 2013

Journal of Environmental Science and Health, Part A

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“…USEPA () defines bioavailability as “the fraction of an ingested dose that crosses the gastrointestinal epithelium and becomes available for distribution to internal target tissues organs.” A related term is bioaccessibility, which is defined as the fraction of the chemical extractable from its matrix (e.g., soil, sediment, food) into the gastrointestinal tract that is available for absorption (Ruby et al ; National Research Council ; Koch and Reimer ). Although the full Eco‐SSL wildlife exposure model includes parameters that address contaminant bioavailability and/or bioaccessibility (e.g., absorbed fractions of contaminants from diet and soil [AF ij and AF sj ]), these parameters are assumed to be 100% in the calculation of Eco‐SSLs or in the approach for REACH secondary poisoning assessment.…”

Section: Modeling Considerations To Improve Exposure Estimationmentioning

confidence: 99%

“…Because in vivo measurements are expensive and conditional in nature, in vitro bioaccessibility techniques are used much more frequently. Koch and Reimer () provide an extensive review of current of in vitro bioaccessibility extraction methods, frequently referred to as PBETs that have been developed for the study of contaminants in soil, sediment, and biological matrices. Many of these methods are based on extraction protocols used in pharmaceutical and nutrition fields.…”

Section: Modeling Considerations To Improve Exposure Estimationmentioning

confidence: 99%

“…Although one of the first bioaccessibility methods developed (Ruby et al ) was based on rabbit physiology, most subsequent work, both in terms of methods development and in terms of evaluation of analyte‐ or location‐specific bioaccessibility, have focused on human health (Koch and Reimer ). These models may be used to support ecological risk assessments (Ollson et al ); however, they are most suitable for a subset of mammalian receptors (those with simple monogastric digestive physiology) and may be sources of considerable uncertainty due to the diversity of digestive physiology among mammalian taxa.…”

Section: Modeling Considerations To Improve Exposure Estimationmentioning

confidence: 99%

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Recommendations to improve wildlife exposure estimation for development of soil screening and cleanup values

Sample¹,

Schlekat

Spurgeon

et al. 2013

Integr Envir Assess & Manag

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An integral component in the development of media‐specific values for the ecological risk assessment of chemicals is the derivation of safe levels of exposure for wildlife. Although the derivation and subsequent application of these values can be used for screening purposes, there is a need to identify the threshold for effects when making remedial decisions during site‐specific assessments. Methods for evaluation of wildlife exposure are included in the US Environmental Protection Agency (USEPA) ecological soil screening levels (Eco‐SSLs), registration, evaluation, authorization, and restriction of chemicals (REACH), and other risk‐based soil assessment approaches. The goal of these approaches is to ensure that soil‐associated contaminants do not pose a risk to wildlife that directly ingest soil, or to species that may be exposed to contaminants that persist in the food chain. These approaches incorporate broad assumptions in the exposure and effects assessments and in the risk characterization process. Consequently, thresholds for concluding risk are frequently very low with conclusions of risk possible when soil metal concentrations fall in the range of natural background. A workshop held in September, 2012 evaluated existing methods and explored recent science about factors to consider when establishing appropriate remedial goals for concentrations of metals in soils. A Foodweb Exposure Workgroup was organized to evaluate methods for quantifying exposure of wildlife to soil‐associated metals through soil and food consumption and to provide recommendations for the development of ecological soil cleanup values (Eco‐SCVs) that are both practical and scientifically defensible. The specific goals of this article are to review the current practices for quantifying exposure of wildlife to soil‐associated contaminants via bioaccumulation and trophic transfer, to identify potential opportunities for refining and improving these exposure estimates, and finally, to make recommendations for application of these improved models to the development of site‐specific remedial goals protective of wildlife. Although the focus is on metals contamination, many of the methods and tools discussed are also applicable to organic contaminants. The conclusion of this workgroup was that existing exposure estimation models are generally appropriate when fully expanded and that methods are generally available to develop more robust site‐specific exposure estimates. Improved realism in site‐specific wildlife Eco‐SCVs could be achieved by obtaining more realistic estimates for diet composition, bioaccumulation, bioavailability and/or bioaccessibility, soil ingestion, spatial aspects of exposure, and target organ exposure. These components of wildlife exposure estimation should be developed on a site‐, species‐, and analyte‐specific basis to the extent that the expense for their derivation is justified by the value they add to Eco‐SCV development. Integr Environ Assess Manag 2014;10:372–387. © 2013 The Authors. Integrated Environmen...

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“…However, sequential extraction or fractionation tests have been commonly the method of choice so as to provide regarding detailed insight into different metal-soil associations [2,4,5,[13][14][15][16][17], by exploiting a number of extractants of increasing elution strength. Fractionation studies are aimed at determining the chemical forms in which metals occur, because metal mobility, bioaccessibility and bioavailability strongly depend on their chemical and mineralogical forms [2,4,5,[13][14][15][16][17]. Sequential extraction protocols individually separate 4 $ 6 pools of chemical forms of metal species that have different leachability, including the water soluble fraction, the ion-exchangeable fraction, the carbonate Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/talanta fraction, and metals bound to Fe-Mn oxyhydroxides and organic matter.…”

Section: Introductionmentioning

confidence: 99%

Dynamic leaching and fractionation of trace elements from environmental solids exploiting a novel circulating-flow platform

Mori

Nakano

Sasaki

et al. 2016

Talanta

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Bioaccessibility Extractions for Contaminant Risk Assessment

Cited by 10 publications

References 184 publications

Variability of bioaccessibility results using seventeen different methods on a standard reference material, NIST 2710

Variability of bioaccessibility results using seventeen different methods on a standard reference material, NIST 2710

Recommendations to improve wildlife exposure estimation for development of soil screening and cleanup values

Dynamic leaching and fractionation of trace elements from environmental solids exploiting a novel circulating-flow platform

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