Grantee Research Project Results
Final Report: Nanoparticle Stability in Natural Waters and its Implication for Metal Toxicity to Water Column and Benthic Organisms
EPA Grant Number: R833324Title: Nanoparticle Stability in Natural Waters and its Implication for Metal Toxicity to Water Column and Benthic Organisms
Investigators: Ranville, James , Butler, Barbara , Jackson, Brian
Institution: Colorado School of Mines , Dartmouth College
EPA Project Officer: Aja, Hayley
Project Period: April 15, 2007 through April 14, 2011
RFA: Exploratory Research: Nanotechnology Research Grants Investigating Environmental and Human Health Effects of Manufactured Nanomaterials: a Joint Research Solicitation-EPA, NSF, NIOSH, NIEHS (2006) RFA Text | Recipients Lists
Research Category: Nanotechnology , Safer Chemicals
Objective:
The overall hypothesis is that metal-containing manufactured nanomaterials could pose an exposure and toxicological risk to aquatic organisms. The toxic ‘species’ may be the nanoparticle or dissolved metal ions liberated following (partial) dissolution. Furthermore, exposure in the water column will be a function of dissolution rate and aggregation rate of the nanoparticle. We proposed to address the following objectives in this research:
- Determine the stability (against aggregation and dissolution) of nanoparticles as a function of water composition.
- Determine the uptake and toxicity of nanoparticles to water column organisms.
- Determine the influence of aggregation on nanoparticle uptake by Daphnia magna under variable water chemistry.
- Develop better methods to measure exposure concentrations of nanoparticles.
Summary/Accomplishments (Outputs/Outcomes):
At its inception, the project was focused on examining the aquatic toxicity of engineered nanoparticles, specifically CdSe/ZnS quantum dots. The goal was primarily to compare the toxicity of Cd in dissolved and ENP form to look for a “nano-effect,” in this case the effect being a greater toxicity than the equivalent dose of soluble Cd. As the project progressed it became clear that significant knowledge gaps exist in understanding the exposure component of risk. Part of the issue, with respect to exposure assessment, is the lack of sound nanometrology tools. Therefore we expanded the objectives of the research to include the development of nanometrology for exposure assessment. Specifically we further developed the technique of single particle ICP-MS (Sp ICP-MS) for the detection, quantification, and characterization of metal-containing ENPs. The improvements we have made in the Sp ICP-MS technique are a significant product of the research.
We examined the toxicity of CdSe/ZnS quantum dots to Ceriodaphnia dubia in soft, moderately hard, and hard water. Compared to dissolved Cd, QDs were less toxic, whereas compared to dissolved Zn, QDs appear to have similar toxicities. Water hardness did not appear to significantly impact QD toxicity, contrary to that seen for dissolved Cd. This suggests a different route of Cd exposure for the QD, most likely through ingestion. Overall, these results show that QDs can cause harmful effects to Daphnia, however they do not display an enhanced toxic effect over that seen for their constituent metals. Thus QD toxicity only occurs at relatively high concentrations, which is unlikely to occur in aquatic environments.
We examined the effect of surface coatings on the toxicity of QDs to Daphnia magna. In this study we found that one of the QDs contained an excess of Cd, presumably from poor manufacturer quality control. Furthermore this QD was unstable and released dissolved Cd over the course of the acute exposure, resulting in high toxicity. In this study we also employed field flow fractionation ICP-MS (FFF-ICP-MS) to provide more detailed characterization of the QDs. The FFF-ICP-MS method was able to show that the excess Cd was associated with the QD and not a dissolved impurity. The demonstration that FFF-ICP-MS can provide detailed information that can inform toxicity studies was a significant outcome of this study.
Given that aggregation can significantly affect exposure to aquatic species we examined this for gold NPs. We chose to examine gold to allow us to examine NP uptake without the complication of toxic effects. Exposure to pre-aggregated AuNP for 48 h in hard water did not show any significant difference in uptake from that seen for unaggregated NPs. This suggests D. magna can also ingest settled AuNP aggregates. The conclusion from this result is that water column organisms might not be protected from NP exposures by the processes of aggregation and settling. Furthermore, D. magna exposed to AuNPs shed their exoskeleton whereas the control did not generate any molts over 48 h. This implies that D. magna removed AuNPs on their exoskeleton by producing molts to decrease any adverse effects of adhered AuNPs. This result demonstrates that the physical effects of NPs, even chemically inert NP such as Au, can cause harm to aquatic organisms.
Finally, we developed the technique of single particle ICP-MS as an improved tool for the exposure assessment of metal containing NPs. Sp ICP-MS, a novel application of ICP-MS, provides number, size, and composition data for nanoparticles as small as 20nm at environmentally relevant concentrations as low as 5 ppt. Furthermore, the distinction and quantification of dissolved vs. nanoparticulate constituents is possible. Specific method improvements included: a new approach to size calibration, defining the dissolved metal background, determining the applicable concentration range, and ICP-MS optimization. The development of this analytical technique provides a powerful tool for research of inorganic NP behavior in environmental and biological systems, and represents the most important achievement of our research.
Journal Articles on this Report : 9 Displayed | Download in RIS Format
Other project views: | All 41 publications | 9 publications in selected types | All 9 journal articles |
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Hassellov M, Readman JW, Ranville JF, Tiede K. Nanoparticle analysis and characterization methodologies in environmental risk assessment of engineered nanoparticles. Ecotoxicology 2008;17(5):344-361. |
R833324 (2007) R833324 (Final) |
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Jackson BP, Pace HE, Lanzirotti A, Smith R, Ranville JF. Synchrotron X-ray 2D and 3D elemental imaging of CdSe/ZnS quantum dot nanoparticles in Daphnia magna. Analytical and Bioanalytical Chemistry 2009;394(3):911-917. |
R833324 (Final) |
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Jackson BP, Bugge D, Ranville JF, Chen CY. Bioavailability, toxicity, and bioaccumulation of quantum dot nanoparticles to the amphipod Leptocheirus plumulosus. Environmental Science & Technology 2012;46(10):5550-5556. |
R833324 (Final) |
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Lee B-T, Ranville JF. The effect of hardness on the stability of citrate-stabilized gold nanoparticles and their uptake by Daphnia magna. Journal of Hazardous Materials 2012;213-214:434-439. |
R833324 (Final) |
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Mitrano DM, Lesher EK, Bednar A, Monserud J, Higgins CP, Ranville JF. Detecting nanoparticulate silver using single-particle inductively coupled plasma-mass spectrometry. Environmental Toxicology and Chemistry 2012;31(1):115-121. |
R833324 (Final) |
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Nowack B, Ranville JF, Diamond S, Gallego-Urrea JA, Metcalfe C, Rose J, Horne N, Koelmans AA, Klaine SJ. Potential scenarios for nanomaterial release and subsequent alteration in the environment. Environmental Toxicology and Chemistry 2012;31(1):50-59. |
R833324 (Final) |
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Pace HE, Lesher EK, Ranville JF. Influence of stability on the acute toxicity of CdSe/ZnS nanocrystals to Daphnia magna. Environmental Toxicology and Chemistry 2010;29(6):1338-1344. |
R833324 (Final) |
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Pace HE, Rogers NJ, Jarolimek C, Coleman VA, Higgins CP, Ranville JF. Determining transport efficiency for the purpose of counting and sizing nanoparticles via single particle inductively coupled plasma mass spectrometry. Analytical Chemistry 2011;83(24):9361-9369. |
R833324 (Final) |
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Pace HE, Rogers NJ, Jarolimek C, Coleman VA, Gray EP, Higgins CP, Ranville JF. Single particle inductively coupled plasma-mass spectrometry: a performance evaluation and method comparison in the determination of nanoparticle size. Environmental Science & Technology 2012;46(22):12272-12280. |
R833324 (Final) |
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Supplemental Keywords:
quantum dots, bioavailability, aggregation, μ-XRF, Scientific Discipline, Health, Risk Assessments, Health Risk Assessment, Biochemistry, bioavailability, biochemical research, nanotechnology, analysis of chemical exposure, bioaccumulation, toxicologic assessment, cellular response to nanoparticles, nanomaterials, nanoparticle toxicity, biogeochemistry, nanochemistry, manufactured nanomaterials
, Health, Scientific Discipline, Health Risk Assessment, Risk Assessments, Biochemistry, biological pathways, nanochemistry, bioavailability, nanotechnology, manufactured nanomaterials, nanomaterials, toxicologic assessment, biogeochemistry, nanoparticle toxicity, cellular response to nanoparticles, analysis of chemical exposure, bioaccumulation
Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.