Internal exposure: Linking bioavailabilty to effects

Swiss Federal Institute for Environmental Science and Technology (EAWAG).
Environmental Science and Technology (Impact Factor: 5.33). 01/2005; 38(23). DOI: 10.1021/es0406740
Source: OAI


Traditionally, ecotoxicological data have been collected by adding a pollutant to a test system, such as an aquarium with fish, until a clearly distinguishable effect was observed. However, researchers have moved on to more sophisticated tests. Beate I. Escher at the Swiss Federal Institute for Environmental Science and Technology (EAWAG) and Joop L. M. Hermens at Utrecht University (The Netherlands) review these developments and show how internal exposure data could improve risk assessment and bridge the gap between human health and environmental risk assessment.

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    • "However, the use of chemical concentrations as indicators of environmental hazards can be questionable, because the external concentration required to have an effect varies with uptake route, duration and history of exposure, chemical composition of the exposure medium, and the biology and ecology of the species used for testing (Niyogi and Wood, 2004; Sappal et al., 2009; Rosabal et al., 2012). Recently, it has been found that chemical residues or the degree of biological damage at target sites or receptors provide an easier and more reliable means of assessing the dose or toxicity at the target site (Seebaugh and Wallace, 2009; Lee et al., 2002; Escher and Hermens, 2004; Ashauer and Escher, 2010). Biomarkers have therefore been suggested as effective tools for assessing risk from field exposure because they integrate the exposure route, time and concentration of chemical uptake, and the induced intrinsic responses of exposed organisms at individual and population levels (Brooks et al., 2009; Peles et al., 2012; Pain-Devin et al., 2014). "
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    ABSTRACT: Branchial Na(+)-K(+)-ATPase (NKA) activity has been suggested as a promising biomarker for assessing metal stress in aquatic organisms. However, studies that systematically show the effectiveness of using NKA activity to detect metal exposure and toxicity at the individual level are limited. In this study, we aimed to determine whether branchial NKA activity mechanistically responds to the accumulation of waterborne copper (Cu) and accounts for observed toxicity over time under environmentally-relevant and aquafarming Cu exposure levels (0.2, 1 and 2mgL(-1)). Temporal trends in Cu accumulation and the corresponding responses of branchial NKA activity resulting from Cu exposure were investigated in laboratory experiments conducted on juvenile tilapia (Oreochromis mossambicus), a freshwater teleost that shows potential as a bioindicator of real-time and historical metal pollution. We used the process-based damage assessment model (DAM) to inspect the time course of Cu toxicity by integrating the compensation process between Cu-induced inhibition and repair of branchial NKA activity. NKA activity acted as a sensitive biomarker for Cu exposure and accumulation in tilapia, which showed induced impairment of osmoregulation and lethality when they were exposed to environmentally relevant levels (0.2mgL(-1)), but not to higher exposure levels (1 and 2mgL(-1)) in aquaculture farms or contaminated aquatic ecosystems. This study highlights the benefits and limitations of using branchial NKA activity as a sensitive biomarker to assess the health status of a fish population and its ecosystem. Copyright © 2015 Elsevier B.V. All rights reserved.
    Full-text · Article · Mar 2015 · Aquatic toxicology (Amsterdam, Netherlands)
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    • "The observed effects are often compared to external concentrations but for a better understanding of toxic effects the internal concentrations should be known (Escher and Hermens, 2004). We have recently published an analytical method to determine internal concentrations in ZFE (Brox et al., 2014). "
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    ABSTRACT: The chorion and the perivitellin space which surround unhatched zebrafish embryos (ZFE, Danio rerio) may affect the determination of internal concentrations of study compounds taken up in early life-stages of ZFE. Internal concentration-time profiles were gathered for benzocaine, caffeine, clofibric acid, metribuzin and phenacetin as study compounds over 96 hours of exposure starting with ZFE at 4 hours post-fertilization. Liquid chromatography coupled to tandem-mass spectrometry (LC-MS/MS) was used to determine the concentration of the study compounds from intact (i.e. unhatched), dechorionated and from hatched ZFE. The mass of the study compounds per ZFE was 5–30 ng higher for intact ZFE compared to dechorionated ones. Thus, internal concentrations were overestimated if only intact ZFE were analyzed. Dechorionation of unhatched ZFE after their exposure is proposed to determine the true internal concentration in the embryo. For the compounds studied here the mass of the study compounds determined in unhatched ZFE after a short term (5 min) exposure provided a reasonable estimate of the mass taken up by the chorion and the PVS. This mass can be subtracted from the total mass found in unhatched ZFE to calculate the true internal mass. Estimating the mass in the chorion and the PVS from the concentration of the study compound in the external exposure medium and the volume of the PVS provided no reasonable results.
    Full-text · Article · Dec 2014 · Aquatic Toxicology
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    • "PSDs can be used to assess exposure and contamination in water [8,9]. The freely dissolved (Cfree) forms of hydrophobic contaminants can be absorbed by or moved through biological membranes of organisms, where they may exert toxic effects [10,11]. PSDs mimic these passive uptake processes; they sequester and concentrate contaminants, providing time-integrated measures of bioavailable (Cfree) contaminant load [12]. "
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    ABSTRACT: It is difficult to assess pollution in remote areas of less-developed regions owing to the limited availability of energy, equipment, technology, trained personnel and other key resources. Passive sampling devices (PSDs) are technologically simple analytical tools that sequester and concentrate bioavailable organic contaminants from the environment. Scientists from Oregon State University and the Centre Régional de Recherches en Ecotoxicologie et de Sécurité Environnementale (CERES) in Senegal developed a partnership to build capacity at CERES and to develop a pesticide-monitoring project using PSDs. This engagement resulted in the development of a dynamic training process applicable to capacity-building programmes. The project culminated in a field and laboratory study where paired PSD samples were simultaneously analysed in African and US laboratories with quality control evaluation and traceability. The joint study included sampling from 63 sites across six western African countries, generating a 9000 data point pesticide database with virtual access to all study participants.
    Full-text · Article · Apr 2014 · Philosophical Transactions of The Royal Society B Biological Sciences
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