2011 Progress Report: Consortium for Manufactured Nanomaterial Bioavailability & Environmental Exposure
EPA Grant Number:
Consortium for Manufactured Nanomaterial Bioavailability & Environmental Exposure
Colvin, Vicki L.
, Chipman, Kevin
, Fernandes, Teresa
, Klaine, Stephen J.
, Lead, Jamie
, Luoma, Sam
, Stone, Vicki
, Tyler, Charles
, Valsami-Jones, Eugenia
, Viant, Mark
Alvarez, Pedro J.
Colvin, Vicki L.
Klaine, Stephen J.
Edinburgh Napier University
Natural History Museum (London)
University of Birmingham
University of California - Davis
University of Exeter
EPA Project Officer:
August 1, 2010 through
August 1, 2013
(Extended to December 31, 2015)
Project Period Covered by this Report:
August 1, 2010 through August 1,2011
Environmental Behavior, Bioavailability and Effects of Manufactured Nanomaterials - Joint US – UK Research Program (2009)
In order to fully and sustainably apply nanotechnology innovations, it is crucial to minimize any unintended environmental impacts resulting from the application of manufactured nanomaterials (NM). To realize this vision, industry and policymakers must base risk management decisions on sound scientific information about the environmental fate of NM; their availability to receptor organisms (including related concepts such as uptake); and any resultant biological effects (toxicity). This basic knowledge can be effectively conveyed by validated models that describe NM behavior and relate this data to information about NM structure and relevant environmental chemistry. These models, whether conceptual or predictive in nature, will give decision-makers the tools to grapple with the nearly infinite forms of possible NM, as well as explore the effects of various risk mitigation strategies. Towards this end, the nanoBEE consortium will develop and refine, using empirical data, a critical subset of models focused on exposure to NM and their bioavailability in the environment.
The methodological approach in the nanoBEE consortium is summarized in Figure 1. Tunable and uniform NM’s are characterized appropriately with existing and novel methods developed in this consortium. The libraries will underpin steady-state and dynamic laboratory and mesocosm experiments to understand NM environmental chemistry, transport, bioavailability and toxicity. These data sets are being used to validate exposure-, bioavailability- and toxicity-based models, and then merged and refined through experiments. The result will be an integrated and validated set of models (EEM-BDM-BLM) (EEM: Environmental Exposure Model; BDM: Biodynamic Model; BLM: Biotic Ligand Model), with, we anticipate, some direct integration between BDM-BLM. Research in the nanoBEE consortium is structured by 5 primary objectives, and 12 tasks listed below. The produced data and models will link to risk assessment modelling strategies.
Objective 1: Nanomaterial Library Production, Characterization
Objective 2: Aqueous electron tomography of nanomaterials
Objective 3: Environmental chemistry, fate and exposure models (EEMs)
Objective 4: NM association with organisms and the biodynamic model
Objective 5: Effects on aquatic organisms – towards a nano-BLM model
The project has 5 main Objectives, which include a large number of specific tasks. Excellent progress has been made on each Objective and almost all tasks.
Objective 1. The focus of the project initially has been on silver nanoparticles (NPs), and the laboratories of Colvin, Lead and Valsami-Jones laboratories have synthesized a range of NPs with different sizes, surface chemistries and shapes. This library of NPs will underpin the successful completion of the project. Although Ag is the primary focus, other NPs of Au, ceria and titania have been produced with a range of properties.
The NPs produced have been quantified and characterized under a range of conditions relevant to toxicological exposures and environmental systems using an appropriate multi-method approach, and an excellent understanding of their dynamic changes over relevant timescales has been investigated, which will inform on all toxicological and environmental data.
Objective 2 required the development of high resolution cryo-(S)TEM tomography using fiducial markers to ensure accuracy. Both TEM and STEM have been used successfully, and equipment for cryological and tomographic analysis has been purchased and installed. Initial results are extremely encouraging with near single atom resolution combined with spatially resolved EELS providing novel information about the surface chemistry of Ag and ceria NPs in relevant media. Full development of tomographic aspects is expected in years 2-3.
Objective 3 has investigated the partitioning and characterization of NPs in relevant systems (waste treatment, surface water, soil) and significant progress made. The relevant mesocosm systems are in place for short-term studies, and laboratory scale longer term projects have been set up and are currently running. Links to Nowack’s laboratory for modeling studies are in place to ensure data compatibility.
Objectives 4 and 5 are considered together and they investigate NP bioavailability and toxicity, respectively. The aim is to parameterise the biodynamic model (bioavailability) and the biotic ligand model (BLM) for toxicity. Excellent initial progress has been made with a range of organisms such as bacteria, algae, daphnia, plants, snails and fish being exposed to both Ag and Au (each with different properties of size, surface chemistry etc), involving the laboratories at UC Davis/USGS, Clemson, Rice, Exeter, Birmingham and Heriot Watt. Acute toxicity has been determined in most cases and some progress towards mechanisms of toxicity has been made using traditional assays and molecular methods. Progress in developing relevant methods for in vitro exposures have been made where in vivo exposures are difficult on a large scale. For some of the organisms, we have already made substantial progress in quantifying uptake, depuration and other rates for the biodynamic model.
Acute toxicity for a range of NP types quantified
Dissolution, toxicity and other behaviour are strongly dependent on surface chemistry, including the nature of the capping agent
Maternal transfer in fish of Ag NPs
Ag NPs are bioavailable
Toxicity at least partly due to dissolution
The future activities will follow the expected progress plan developed initially for this project. The following activities will be the focus of Year 2 (2011-2012):
Synthesise different NPs, including isotopically labelled ones (Years 2-3)
Develop cryo STEM tomography with fiducial markers (Year 2)
Apply isotopically labelled NPs to allow low exposure concentrations to be used (Years 2-4)
Investigate maternal transfer (Years 2-3)
Investigate NP effects on bacterial biogeochemical services (Years 2-4)
Investigate molecular responses to fully determine mechanisms pof action in Daphnia (Years 2-3)
Throughout this second year, knowledge exchange will continue through relevant conferences and publications as well as wide interactions with relevant stakeholders both formally and informally.
In addition, the close links established during the first year between all partners will continue. For instance, Rice, NHM, and Birmingham have all linked with partners to provide relevant NPs, and UC Davis, USGS, and Clemson have all discussed appropriate model parameters for ecotoxicology exposures with other partners.
on this Report
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nanotechnology, nanoscience, bioavailability, emerging contaminants, environmental modeling, manufactured nanoparticles, biotic ligand model, biodynamic model, environmental exposure model
Progress and Final Reports:
2013 Progress Report