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De Laender F.,Ghent University | Van Sprang P.,ARCHE Consulting | Janssen C.R.,Ghent University
Environmental Toxicology and Chemistry | Year: 2013

Ecological risk assessments of chemicals can be informed by a suite of effect models, including population and food web models. In the risk assessments conducted under EU regulation 793/93/EC, however, applications of such effect models are extremely scarce and toxicity-extrapolation approaches are often used instead. The objective of the present study was to re-evaluate these risk assessments using two types of effect models: species sensitivity distributions (SSDs, non-mechanistic), and food web models (mechanistic). Species sensitivity distributions significantly fitted the available toxicity data for up to 35% of the chemicals, depending on the trophic levels included and the amount of data available. Median hazardous concentrations for 5% of the species (HC5-50) estimated by the SSDs were less accurate predictors of measured community-level no observed effect concentration than food web model-derived HC5-50s, albeit data were available for seven chemicals only. For datasets with more than 10 data points, the 90% confidence interval of the estimated HC5s was narrower for the food web modeling approach than for the SSD approach. The HC5-50s predicted by the two approaches were two to five times (metals) and 10 to 100 times (organic chemicals) higher than the predicted no effect concentrations (PNECs) for the aquatic environment listed in the risk assessment reports. This suggests that the derived PNECs are protective for aquatic ecosystems. © 2012 SETAC.

Regoli L.,IMOA | Van Tilborg W.,VTBC Beekhuizenseweg 46 | Heijerick D.,ARCHE Consulting | Stubblefield W.,Oregon State University | Carey S.,IMOA
Science of the Total Environment | Year: 2012

In a regulatory context, bioaccumulation or bioconcentration factors are used for considering secondary poisoning potential and assessing risks to human health via the food chain. In this paper, literature data on the bioaccumulation of molybdenum in the aquatic organisms are reviewed and assessed for relevance and reliability. The data available in the literature were generated at exposure concentrations below those recommended in the REACH registration dossiers for molybdenum compounds i.e. PNECfreshwater 12.7mg Mo/L. To address possible environmental concerns at regulatorily-relevant molybdenum concentrations, both a field study and a laboratory study were conducted. In the field study, whole body and organ-specific molybdenum levels were evaluated in fish (eel, stickleback, perch, carp bream, roach) held in the discharge water collector tanks of a molybdenum processing plant, containing a mean measured molybdenum level of 1.03mg Mo/L. In the laboratory study, rainbow trout were exposed to two different nominal molybdenum levels (1.0 and 12.7mg Mo/L), for 60days followed by a 60-day depuration period. Whole body concentrations in rainbow trout during the exposure period were between <0.20 and 0.53mg Mo/L. Muscle tissue molybdenum concentrations in fish taken from both experiments remained below 0.2mg/kg dry wt. These studies show an inverse relationship between exposure concentration and bioconcentration or bioaccumulation factor for molybdenum. In aquatic organisms, and in fish in particular, internal molybdenum concentrations are maintained in the presence of variation in external molybdenum concentrations. These observations must be considered when evaluating potential risks associated with the bioconcentration and/or bioaccumulation of molybdenum in the aquatic environment. © 2012.

Kwok K.W.H.,Duke University | Batley G.E.,CSIRO | Wenning R.J.,ENVIRON International Corporation | Zhu L.,Nankai University | And 2 more authors.
Environmental Science and Pollution Research | Year: 2014

During the International Conference on Deriving Environmental Quality Standards for the Protection of Aquatic Ecosystems held in Hong Kong in December 2011, an expert group, comprising scientists, government officials, and consultants from four continents, was formed to discuss the important scientific and regulatory challenges with developing sediment quality guidelines (SQGs). We identified the problems associated with SQG development and made a series of recommendations to ensure that the methods being applied were scientifically defensible and internationally applicable. This document summarizes the key findings from the expert group. To enable evaluation of current SQG derivation and application systems, a feedback mechanism is required to communicate confounding factors and effects in differing environments, while field validation is necessary to gauge the effectiveness of SQG values in sediment quality assessments. International collaboration is instrumental to knowledge exchange and method advancement, as well as promotion of 'best practices'. Since the paucity of sediment toxicity data poses the largest obstacle to improving current SQGs and deriving new SQGs, a standardized international database should be established as an information resource for sediment toxicity testing and monitoring data. We also identify several areas of scientific research that are needed to improve sediment quality assessment, including determining the importance of dietary exposure in sediment toxicity, mixture toxicity studies, toxicity screening of emerging chemicals, how climate change influence sediments and its biota, and possible use of new toxicity study approaches such as high throughput omic-based toxicity screenings. © 2013 Springer-Verlag Berlin Heidelberg.

Smolders E.,Catholic University of Leuven | Oorts K.,ARCHE Consulting | Peeters S.,Catholic University of Leuven | Lanno R.,Ohio State University | Cheyns K.,Coda Research
Science of the Total Environment | Year: 2015

The fate and effects of toxic trace metals in soil freshly spiked soluble metal salts do not mimic those of metals in the field. This study was set up to test the magnitude of effects of salinity, acidification, and ageing on toxicity of lead (Pb) to plants, invertebrates and soil microbial processes. Three soils were spiked with Pb2+ salts up to a concentration of 8000mgPb/kg and were tested either after spiking, after soil leaching followed by pH correction, or after a 5-year outdoor ageing period with free drainage followed by pH correction. Soil solution ionic strength exceeded 150mmol/L in soils tested directly after spiking and this decreased partially after leaching and returned back to background values after 5-year outdoor equilibration. Chronic toxicity to two plants, two invertebrates, and three microbial endpoints was consistently found in all spiked soils that were not leached. This toxicity significantly decreased or became absent after 5years of ageing in 19 of the 20 toxicity tests by a factor 8 (median factor range: 1.4->50), measured by the factor increase of total soil Pb dose required to induce 10% inhibition. The toxicity of Pb in leached soils was intermediate between the other two treatments. The lowest detectable chronic thresholds (EC10) in aged soils ranged 350-5300mgPb/kg. Correlation analysis, including data of Pb2+ speciation in soil solution, suggests that reduced ionic strength rather than acidification or true ageing is the main factor explaining the soil treatment effects after spiking. It is suggested that future toxicity studies should test fine PbO powder as a relevant source for Pb in soils to exclude the confounding salt effects. © 2015 Elsevier B.V.

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