Grantee Research Project Results
Final Report: NCCLCs: Life Cycle of Nanomaterials (LCnano)
EPA Grant Number: R835580Title: NCCLCs: Life Cycle of Nanomaterials (LCnano)
Investigators: Westerhoff, Paul , Fairbrother, D. Howard , Theis, Thomas L. , Hutchison, James E. , Plata, Desirée L.
Institution: Arizona State University , Duke University , Oregon State University , Purdue University , University of Oregon , Yale University , The Johns Hopkins University , Carnegie Mellon University , Colorado School of Mines , University of Illinois at Chicago
Current Institution: Arizona State University , Carnegie Mellon University , Colorado School of Mines , Duke University , Oregon State University , Purdue University , The Johns Hopkins University , University of Illinois at Chicago , University of Oregon , Yale University
EPA Project Officer: Aja, Hayley
Project Period: March 19, 2014 through March 18, 2018 (Extended to August 30, 2019)
Project Amount: $5,000,000
RFA: EPA/NSF Networks for Characterizing Chemical Life Cycle (NCCLCs) (2013) RFA Text | Recipients Lists
Research Category: Chemical Safety for Sustainability
Objective:
Because engineered nanomaterials (NMs) have transformative benefits to individuals and society, they are being incorporated into many products. However, tremendous uncertainty presently exists in our ability to predict or manage risks from nano-enabled products across their life cycles. To address knowledge gaps that prevent the sustainable development of nanoenabled products, a highly interdisciplinary group of environmental scientists, engineers, and chemists with well-recognized expertise in NM fabrication, analytics, product release testing, exposure forecasting, high throughput toxicity screening, and life cycle evaluation created a research network on the life cycle of nanomaterials (LCnano). We hypothesized that the desirable physicochemical properties that create unique NM functionality can also influence inherent hazards and potential exposure routes. LCnano’s overarching goal was to elucidate NM property-exposure and property-hazard relationships from a life cycle perspective and to provide predictive models for unintended implications of NMs that will improve design of safe nano-enabled products and processes. To inform risk managers, LCnano employed high throughput functional assays to quantify material attributes that serve as proxies for short- and long-term risk (material exposure, hazard, reactivity, and distribution). To inform designers of nano-enabled products about balances between performance and risk, LCnano evaluated nano-enabled products for facilitating direct and translational methods in the development of material property-exposure and property-hazard relationships for identifying and subsequently minimizing risk for a wide array of existing products, helping ensure sustainable design of future, transformative nano-enabled products.
Summary/Accomplishments (Outputs/Outcomes):
Because an ad hoc study of the properties of released NMs from thousands of products would have been fruitless, LCnano focused our efforts in four shared NMs (Ag0, TiO2, SiO2, and multiwall carbon nanotube (MWCNTs)) and four industrially- and commercially-relevant product lines:
• Product line A: NMs dispersed in liquids used in industrial manufacturing (e.g.,polishing agents)
• Product line B: NMs dispersed in products (e.g., foods)
• Product line C: NMs embedded in composite polymers (e.g., thermoplastics,membranes for water filtration)
• Product line D: NMs coated on the surfaces of flexible polymeric materials (e.g.,textiles).
Results are grouped into 6 themes, summarized below.
Advancing the Environmental Applications of Engineering Nanomaterials
Nanomaterials can be used to treat a wide range of pollutants in water or soils by leveraging their unique properties. Many benefits emerged, including remediating organic-pollutant contaminated soils, removing contaminants from water, enabling advanced oxidation and advanced reduction processes, increasing fertilizer uptake in agricultural applications, and reducing nitrate fertilizer leaching into groundwater, and . Through substantial literature reviews and collection of new field data aimed at understanding the life-cycle trade-offs amongst benefits and hazards of different products, we concluded that nanomaterials posed low risks in drinking water. Life cycle assessments also suggest net benefits exist for using nanotechnology in plant-related agricultural applications.
We also investigated Industrial uses of NMs, including dispersing in liquids to polish products (Product Line A). While the nanomaterials never end up in consumer products, they are released into industrial wastewaters. Through modeling how various III-V elements (Ga, In, As) interact with CMP nanomaterials, LCnano helped advance the understanding of monitoring and safely using these industrial processing agents. LCnano also investigated green synthesis methods for carbon nanotubes and considered applications that would have broad environmental sustainability benefits. Overall we concluded that acetylene-fed CNT growth optimizes energy, performance, and waste metrics. We also learned that low oxygen content carbon nanotubes are promising alternatives to traditional flame retardant materials, showing high efficacy relative to their mass loading, but durability challenges exist.
Nanoparticle Extraction and Detection in a Variety of Matrices
We developed or enhanced – and then applied -- several methods to detect and measure nanoparticles in various matrices (water, tissue, air, polymers, etc). Techniques included programmable thermal analysis and single particle ICP-MS for mass and number concentration, and colorimetric assays for surface reactivity. In addition, extraction methodologies for natural materials (e.g., plant tissue, fish tissue, lung tissue, and bodily fluids), personal care products, and engineering polymers.
Nanomaterial Release Studies
LCnano used several studies to evaluate the release of NMs into water and air during use. We concluded it is possible to select specific techniques to bind nano-silver on textiles (Product Lines C and D) to both achieve their desired function (i.e., reduction in odor-causing bacteria) while minimizing the amount of silver leached into washwater over the life of the nano-enabled textile. Similar findings were observed for nano-silver coated onto desalination reverse osmosis polymeric membranes, indicating the ability to translate findings across product use classes. LCnano examined many other use-phase releases of nanomaterials. For example, engineered nanomaterials integrated into polymers (Product Line C) can add strength and durability to high-traffic floor coatings, but can be released during abrasive use or cleaning processes. Engineered nanoparticles are also used in personal supplements and foods (Product Line B). In household use, these often end up in sewage that conveys the nanomaterials to wastewater treatment plants. In recreational use, nanomaterials in personal care products (e.g., sunscreens) are directly released into the environment (e.g., rivers, lakes, swimming pools). We assessed both of these releases and impacts on wastewater treatment plant performance as well as potential impacts on ecosystem processes. The incorporation of NP into sunscreens had limited ecological risk to the endpoints we selected. As a signature project within LCnano, we developed a multi-university network of outdoor weathering stations across the USA and showed that the extent to which local climate can impact engineered nanomaterial degradation and nanomaterial release depends largely on the materials’ intrinsic ability to resist degradation. Geographic differences in humidity and solar irradiation played a major role in the results for lumber pressure treated with micronized copper; samples weathered in wetter climates were depleted of (i.e., released) readily accessible copper within the first year of exposure, while in drier climates, the lack of precipitation led to wood drying and cracking – which in turn led to sustained copper release after a year of weathering. However, polymer nanocomposites composed of carbon nanotubes or silver nanoparticles in either polystyrene, poly(methyl methacrylate), or polycaprolactone released less than 5% of their original imbedded nanomaterial irrespective of the climate to which they were exposed. End-of-life release of nanomaterials (Product Line C) from products is important to quantify, and critical inputs for LCA models. We investigated fate of quantum dot enabled screen displays and nanomaterials in photovoltaic panels. Additionally, because metals in end-of-life wastestreams are important to recover, we investigated the amount and nano-forms of metalbased materials in sewage and sewage sludges, and assessed potential strategies (including nano-enabled treatment technologies) to recover earth abundant and higher value metals.
Nanotoxicological Studies and Impacts Following Nanomaterial Release from Products
In addition to understanding exposure to nanomaterials by developing methods to extract nanomaterials from products, or assess their release during use, LCnano researchers also assessed the potential hazard of nanomaterials. We focused heavily on advancing and applying use of zebrafish embryo high-throughput testing platforms. We found no relationship between the variation in ROS generation and variability in toxicity outcomes when exposing embryonic zebrafish to oxygen-functionalized MWCNTs. The materials toxicity was mostly a function of surface charge and the morphology of the material aggregate in solution, which has not been attributed to toxicity outcomes before. e also evaluated toxicity of nanomaterials versus organic chemicals used in personal care products (e.g., sunscreens and sunblocks) using zebrafish embryo assays. The high throughput platforms faced some challenges related to sedimentation of nanomaterials across the 5-day test, but overall the tests provided valuable tools to understand structure-activity relationships related to both exposure and toxicity of engineered nanomaterials. Engineered nanomaterials can impact cells in the human digestive system, when nanoenabled foods (Product Line B) are ingested. We observed that nano-sized additives in some foods underwent much faster dissolution than larger-sized bulk additives, and this was considered advantageous for delivering nutrients in the gut. While studies can show adverse impacts on gut microvilli, most in vivo models lack the complexity in the human gut. Ongoing work shows that nanosilver, at dosages recommended in supplements, can impact the production of short-chain fatty acids and change the microbial ecology of bacteria in tests conducted using donated human fecal material. While it may initially appear unrelated, the dense biological community in biological wastewater treatment plants can be viewed as a nacroscale view of our gut. We found that WWTPs efficiently removed nanomaterials from wastewater, and only under very high shock loadings do nanomaterials impact wastewater treatment plant performance.
Lifecycle Assessment Advances and Studies
LCnano conducted numerous lifecycle assessments, many around nanosilver enabled technologies. For example, we applied LCA models to examine trade-offs between NM use and increasing food shelf-life in plastic food containers (Product Line C or D) impregnated with nanosilver. We also examined tradeoffs when using nanosilver in textiles to reduce odors during use. Throughout LCnano’s duration we were able to integrate findings to develop design tools for when nano-enabling products have net environmental benefits. We concluded that “nanotizing” a product is seldom a “win” for all parties involved. Tradeoffs nearly always exist, hence a decision framework should be used that permits inclusion of multiple criteria and careful weighing of multiple impacts and outcomes. Coordinating data collection to feed into retrospective and forward-looking dynamic LCA models emerged as an essential strategy within LCnano.
Insights into Science of Networked Teams
Because environmental health and safety considerations of nanomaterials represent significant challenges for industry, multi-disciplinary research consortia are needed to address complex challenges around use, material characterization, and toxicity evaluations. As such, understanding team science emerged as an integral assessment aspect of LCnano, and it also emerged as a valuable learning opportunity for the diverse group of researchers. We applied a number of tools, including the KolbeTM profiling survey, to understand instinctive ways people take action. This improved collaboration between the team members. Communication methods among and external to the team were better understood as the project progressed. We also worked with experts to develop public-facing tools, such as a museum demonstration kit, to better engage and understand nanotechnology.
Journal Articles on this Report : 1 Displayed | Download in RIS Format
Other project views: | All 134 publications | 73 publications in selected types | All 73 journal articles |
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Kidd J, Bi Y, Hanigan D, Herckes P, Westerhoff P. Yttrium Residues in MWCNT Enable Assessment of MWCNT Removal during Wastewater Treatment. NANOMATERIALS 2019;9(5):670. |
R835580 (Final) |
Exit |
Supplemental Keywords:
nanotechnology, exposure, risk, ecological effects, bioavailability, particulates, effluent, metals, aquatic, water, life cycle analysis, Bayesian, environmental chemistry, engineering, modeling, measurement methods, risk, hazardRelevant Websites:
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.
Project Research Results
- 2018 Progress Report
- 2017 Progress Report
- 2016 Progress Report
- 2015 Progress Report
- 2014 Progress Report
- Original Abstract
73 journal articles for this project