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Langdon K.A.,CSIRO | Mclaughlin M.J.,CSIRO | Kirby J.K.,CSIRO | Merrington G.,Wca environment
Environmental Toxicology and Chemistry | Year: 2014

Silver (Ag) is being increasingly used in a range of consumer products, predominantly as an antimicrobial agent, leading to a higher likelihood of its release into the environment. The present study investigated the toxicity of Ag to the nitrification process in European and Australian soils in both leached and unleached conditions. Overall, leaching of soils was found to have a minimal effect on the final toxicity data, with an average leaching factor of approximately 1. Across the soils, the toxicity was found to vary by several orders of magnitude, with concentrations of Ag causing a 50% reduction in nitrification relative to the controls (EC50) ranging from 0.43mg Ag/kg to >640mg Ag/kg. Interestingly, the dose-response relationships in most of the soils showed significant stimulation in nitrification at low Ag concentrations (i.e., hormesis), which in some cases produced responses up to double that observed in the controls. Soil pH and organic carbon were the properties found to have the greatest influence on the variations in toxicity thresholds across the soils, and significant relationships were developed that accounted for approximately 90% of the variability in the data. The toxicity relationships developed from the present study will assist in future assessment of potential Ag risks and enable the site-specific prediction of Ag toxicity. © 2014 SETAC. Source

Handy R.D.,University of Plymouth | Van Den Brink N.,Wageningen University | Chappell M.,U.S. Army | Muhling M.,TU Bergakademie Freiberg | And 11 more authors.
Ecotoxicology | Year: 2012

This review paper reports the consensus of a technical workshop hosted by the European network, NanoImpactNet (NIN). The workshop aimed to review the collective experience of working at the bench with manufactured nanomaterials (MNMs), and to recommend modifications to existing experimental methods and OECD protocols. Current procedures for cleaning glassware are appropriate for most MNMs, although interference with electrodes may occur. Maintaining exposure is more difficult with MNMs compared to conventional chemicals. A metal salt control is recommended for experiments with metallic MNMs that may release free metal ions. Dispersing agents should be avoided, but if they must be used, then natural or synthetic dispersing agents are possible, and dispersion controls essential. Time constraints and technology gaps indicate that full characterisation of test media during ecotoxicity tests is currently not practical. Details of electron microscopy, dark-field microscopy, a range of spectroscopic methods (EDX, XRD, XANES, EXAFS), light scattering techniques (DLS, SLS) and chromatography are discussed. The development of user-friendly software to predict particle behaviour in test media according to DLVO theory is in progress, and simple optical methods are available to estimate the settling behaviour of suspensions during experiments. However, for soil matrices such simple approaches may not be applicable. Alternatively, a Critical Body Residue approach may be taken in which body concentrations in organisms are related to effects, and toxicity thresholds derived. For microbial assays, the cell wall is a formidable barrier to MNMs and end points that rely on the test substance penetrating the cell may be insensitive. Instead assays based on the cell envelope should be developed for MNMs. In algal growth tests, the abiotic factors that promote particle aggregation in the media (e.g. ionic strength) are also important in providing nutrients, and manipulation of the media to control the dispersion may also inhibit growth. Controls to quantify shading effects, and precise details of lighting regimes, shaking or mixing should be reported in algal tests. Photosynthesis may be more sensitive than traditional growth end points for algae and plants. Tests with invertebrates should consider non-chemical toxicity from particle adherence to the organisms. The use of semi-static exposure methods with fish can reduce the logistical issues of waste water disposal and facilitate aspects of animal husbandry relevant to MMNs. There are concerns that the existing bioaccumulation tests are conceptually flawed for MNMs and that new test(s) are required. In vitro testing strategies, as exemplified by genotoxicity assays, can be modified for MNMs, but the risk of false negatives in some assays is highlighted. In conclusion, most protocols will require some modifications and recommendations are made to aid the researcher at the bench. © Springer Science+Business Media, LLC 2012. Source

Langdon K.A.,CSIRO | Mclaughlin M.J.,CSIRO | Kirby J.K.,CSIRO | Merrington G.,Wca environment
Environmental Toxicology and Chemistry | Year: 2015

Silver (Ag) has been shown to exhibit antimicrobial properties; as a result, it is being used increasingly in a wide range of consumer products. With these uses, the likelihood that Ag may enter the environment has increased, predominately via land application of biosolids or irrigation with treated wastewater effluent. The aim of the present study was to investigate the toxicity of Ag to 2 plant species: barley (Hordeum vulgare L. CV Triumph) and tomato (Lycopersicum esculentum) in a range of soils under both leached and unleached conditions. The concentrations that resulted in a 50% reduction of plant growth (EC50) were found to vary up to 20-fold across the soils, indicating a large influence of soil type on Ag toxicity. Overall, barley root elongation was found to be the least sensitive to added Ag, with EC50 values ranging from 51mg/kg to 1030mg/kg, whereas the tomato plant height showed higher sensitivity with EC50 values ranging from 46mg/kg to 486mg/kg. The effect of leaching was more evident in the barley toxicity results, where higher concentrations of Ag were required to induce toxicity. Variations in soil organic carbon and pH were found to be primarily responsible for mitigating Ag toxicity; therefore, these properties may be used in future risk assessments for Ag to predict toxicity in a wide range of soil types. © 2015 SETAC. Source

Gardner M.,Atkins Boreas | Comber S.,Atkins Boreas | Leverett D.,Wca environment | Gravell A.,UK Environment Agency
Analytical Letters | Year: 2012

A series of sample stability tests has been undertaken to support a large UK-based survey of trace substances in wastewater. This program aims to quantify the input of priority chemicals to the aquatic environment via sewage effluent. The stability tests have demonstrated that, in most cases, the proposed approach of chilling samples meets the target that sample concentrations should not change by more than 25%, provided samples are analyzed or otherwise stabilized within 3-5 d. Substances tested fall into three main classes: Instability in effluents greater than the project-based threshold of 25% over 3-5 d can be ruled out provided samples are chilled for: DEHP (DEHA), glyphosate, AMPA, bentazone, mecoprop, ofloxacin, erythromycin, and ibuprofen;Some indication of possible instability up to 25% provided chilled storage periods do not extend beyond 3-5 d for: mercury (note requires acid dichromate preservation on site or as soon as possible), tributyltin, bisphenol A, reactive aluminum (in effluents, note requires filtration on sampling), oxytetracycline, and propranolol; andClear stability problems are demonstrated for salicylic acid (effluents and influents), with indications of important instability (>25%) for bisphenol (effluents) AMPA and glyphosate (influents). © 2012 Copyright Taylor and Francis Group, LLC. Source

Merrington G.,Wca environment | Van Sprang P.,Arche Assessing Risks of Chemicals
Environmental Science and Pollution Research | Year: 2014

Recent technical guidance has been published by the European Commission that outlines methodologies for the derivation of Environmental Quality Standards (EQS) in European surface waters under the Water Framework Directive (WFD). The guidance allows the derivation of a long-term EQS from a small dataset. Specifically an EQS can be derived from just three acute data points, although the safety factors built into such an EQS are large (e.g. up to a factor of 1,000). Large safety factors make such EQS uncertain, and often difficult to achieve in practice. We examine dataset requirements for the derivation of EQS and specifically the minimum number of tests needed for setting EQS for long-term chemical exposures that result in reduced relative uncertainty, as assessed simply through the reduction in standard deviation of the means of the values derived. Using ecotoxicity datasets for four example chemicals, for which EQS have been derived in many jurisdictions, we show that variation in the EQS is greatest when using the minimum dataset allowable under the WFD guidance, but decreases rapidly when seven or more datapoints are available. Increasing the minimum number of ecotoxicity data in deriving an EQS results in a greater understanding of ecotoxicological effects. With this knowledge, the mitigating effects of water chemistry can be accounted for in deriving an EQS, even with relatively limited datasets. The new guidance suggests "simplistic" approaches to account for chemical availability, but does not detail how this might be undertaken. We provide examples of ways by which water chemistry effects can be included in deriving implementable EQS for metals with relatively few reliable and relevant data. © 2013 Springer-Verlag Berlin Heidelberg. Source

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