Grantee Research Project Results
2005 Progress Report: Fate, Transformation and Toxicity of Manufactured Nanomaterials in Drinking Water
EPA Grant Number: R831713Title: Fate, Transformation and Toxicity of Manufactured Nanomaterials in Drinking Water
Investigators: Westerhoff, Paul , Crittenden, John C. , Capco, David , Chen, Yongsheng
Institution: Arizona State University
EPA Project Officer: Hahn, Intaek
Project Period: October 1, 2004 through September 30, 2007
Project Period Covered by this Report: October 1, 2004 through September 30, 2005
Project Amount: $455,000
RFA: Exploratory Research to Anticipate Future Environmental Issues: Impacts of Manufactured Nanomaterials on Human Health and the Environment (2003) RFA Text | Recipients Lists
Research Category: Nanotechnology , Human Health , Safer Chemicals
Objective:
Although the current market for nanomaterials is small and their concentration may not be high enough in the environment to cause human health or environmental problems, this market is increasing rapidly and the discharge of nanomaterials into the environment in the near future could be significant as manufacturing costs decrease and new applications are discovered. The accumulation of nanomaterials in cells may have significant environmental and human impacts. At present, however, very little is known about the fate, transport, transformation, and toxicity of these man-made nanomaterials in the environment. The objectives of this research project are to: (1) characterize the fundamental properties of nanomaterials in aquatic environments; (2) examine the interactions between nanomaterials and toxic organic pollutants and pathogens (viruses); (3) evaluate the removal efficiency of nanomaterials by drinking water unit processes; and (4) test the toxicity of nanomaterials in drinking water using the cell culture model system of the epithelium. This study considers the physical, chemical, and biological implications of nanomaterial fate and toxicity in systems that will provide insight into the potential for nanomaterials to be present and to cause health concern in treated drinking water.
Progress Summary:
Characterization of commercial metal oxide nanoparticles (powder or liquid suspensions) by scanning electron microscopy or by dynamic light scatter after placing these particles in water indicates that these nanomaterials are aggregated when purchased and remain aggregated in solution. Attempts to disaggregate the nanomaterials in water using sonication, pH adjustment, solvent addition, or surfactant addition had minimal effect on mean particle sizes. As a consequence, the metal oxide nanoparticle aggregates range in size from 500 to 10,000 nm in diameter at concentrations of 10 mg/L of nanoparticles. Thus fate and transport of metal oxide nanoparticles may actually depend more on aggregation kinetics than behavior of discrete nanoparticles in water. To address the fate of discrete nanoparticles our team has synthesized metal oxides with mean particle diameters of ~ 10 nm, which are not initially aggregated and will be used in future tests.
Experiments have been conducted that simulate drinking water treatment (jar tests with coagulation, flocculation, sedimentation, and filtration). Both metal coagulants (alum, ferric) and salt (MgCl2) have been used to destabilize or otherwise aggregate metal oxide nanoparticles. Experiments have included titanium, iron, and aluminum oxide nanoparticles, and cadmium quantum dots. Overall, coagulation and sedimentation alone remove 40 to 60 percent of these nanoparticles, and filtration (0.45 μm or 3 μm pore diameter) removes an additional 50 to 80 percent. Ten to 30 percent of some initial nanoparticles remain, however, after this simulated water treatment test.
Trans-Epithelial Electrical Resistance (TEER) measurements have been made using Caco2 BBe (human intestinal cells) grown and maintained with Dulbecco's Modified Eagle Medium ( DMEM) media supplemented with 10 percent fetal bovine serum, penicillin/ streptomycin/ fungizone, and transferrin. Extensive optimization of growth conditions was undertaken. Preliminary experiments indicate a decrease of 10 to 50 percent in TEER within 1 hour after application of metal oxide nanoparticles. Spectroscopic investigations of the cells are underway to determine the mechanism for change in TEER.
Future Activities:
We will continue to implement the research described in our original proposal.
Journal Articles:
No journal articles submitted with this report: View all 12 publications for this projectSupplemental Keywords:
fate, transport, toxicity, manufactured nanomaterials, drinking water,, Health, RFA, Scientific Discipline, Water, Health Risk Assessment, Risk Assessments, Environmental Chemistry, Engineering, Chemistry, & Physics, Biochemistry, Drinking Water, community water system, health effects, toxicity, toxicokinetics, human exposure, engineered nanomaterials, drinking water system, drinking water contaminants, fate and transport, environmental contaminants, ambient particle health effects, nanotechnology, respiratory impact, other - risk assessment, cellular responses, human health effects, human health risk, particle exposure, biochemical researchProgress 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.