Grantee Research Project Results

2006 Progress Report: Fate, Transformation and Toxicity of Manufactured Nanomaterials in Drinking Water

EPA Grant Number: R831713
Title: 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, 2005 through September 30, 2006
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 concerns in treated drinking water.

Progress Summary:

Aggregation studies have been conducted using several types of commercial metal oxide nanoparticles (two types of titanium dioxide, iron(III) oxide, zinc oxide, nickel oxide, and silica in powder form or liquid suspensions), functionalized quantum dots and hematite lab-synthesized nanoparticles. Most experiments were conducted with 10 mg/L of the nanoparticles. Studies were conducted in the presence of simple salts to compress electric double layer of the nanoparticles, to study their aggregation rates. Separate studied used aluminum sulfate to simulate potable drinking water practices. The fate of nanoparticles during drinking water “jar” tests was characterized by changes in dynamic light scattering, zeta potential, scanning electron microscopy (SEM), and acid digestion followed by atomic absorption spectroscopy. Metal oxides and hematite rapidly aggregated in the presence of simple salts, local tap water, and addition of aluminum sulfate. Quantum dots behaved significantly different from the other quantum dots studied. Carboxyl functional groups stabilized quantum dots in suspension (i.e., no aggregation) unless their charge was neutralized by di- or tri-valent cations. This work builds upon results from the first year of the project which showed that most metal oxide nanoparticles are aggregated to micron-size under most drinking water treatment scenarios.

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) supplemented with 10 percent fetal bovine serum, penicillin/streptomycin/ fungizone, and transferrin. Nanoparticles were applied to the tests in the medium. Controls were conducted without nanoparticles or with sodium azide. Aggregation within the medium was observed. Measurements included TEER, live/dead assays, confocal microscopy and SEM imaging, and quantification of passage of nanomaterials across the membrane. Nanoparticles were found to flatten down the microvilli, allowed passage of 1% to ~10% of the nanoparticles, and result in >25% decrease in TEER relative to controls only at very high nanoparticle dosages. Experiments were also conducted in PBS solution (top of cells; DMEM below cells) to minimize nanoparticle aggregation. Experiments using quantum dots and other nanoparticles are ongoing.

An LC/MS method was developed to quantify C60 fullerenes and fullerols at ppb concentrations in water. This will be used in upcoming experiments which were initially limited by other analytical techniques. Previously, the only viable measurement technique of C60 in water was light scattering, but this is not appropriate at low C60 concentrations or after C60 microscopic aggregates form.

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 project

Supplemental 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, environmental contaminants, fate and transport, nanotechnology, ambient particle health effects, respiratory impact, drinking water system, drinking water contaminants, other - risk assessment, cellular responses, human health risk, human health effects, particle exposure, biochemical research

Progress and Final Reports:

Original Abstract

2005 Progress Report

Final Report