Substantial amounts of metallic nanomaterials are being utilized yet there is little knowledge about the effects of these materials in the environment. Preliminary data indicates that copper and silver nanoparticles are acutely toxic in zebrafish and daphnia. The proposed studies will investigate the biological fate and toxicity of metallic nanoparticles in various trophic levels. The overall hypothesis is that exposure to metallic nanoparticles will result in bioaccumulation and trophic transfer different than soluble forms of the metal. Moreover, long-term exposure to nanometallics may produce toxicity that is qualitatively and quantitatively different than soluble metals. To address these hypotheses, 3 specific aims are proposed: 1) To determine metal bioaccumulation and trophic transfer rates in aquatic organisms exposed to metallic nanoparticles; 2) To determine effects of long-term exposure to copper, silver and titania nanomaterials on zebrafish and daphnia; and 3) To determine the role of particle mediated reactive oxygen generation in gill toxicity.
To address these aims, zebrafish (Danio rerio) will be exposed to copper, silver, nickel or titanium dioxide as aqueous solutions or nanoparticle suspensions. The uptake and distribution of metal will be determined for each form in T. tubifex, P. subcapitata, D. pulex, and zebrafish. We will then determine trophic transfer from producer to primary consumer and from primary consumer to secondary consumer. Standard protocols will be utilized to examine long-term toxicity of these particles in zebrafish as adults and at early life stages as well as in daphnia life-cycle assays. These studies will identify threshold values for mortality, embryonic and larval survival and reproduction. They will also determine target tissues for toxicity by examining histological, biochemical and molecular markers of toxicity. Comparison of these markers will allow determination of if nanoparticles produce toxicity that differs from soluble forms of the same metal. Finally, the ability of metallic nanoparticles to produce reactive species will be examined the importance of oxidative stress in gill toxicity will be determined.
Intellectual Merit: The proposed studies represent an interdisciplinary collaboration of toxicologists, engineers, and aquatic pathologists who bring a unique combination of experience, facilities, and resources to bear on the study of environmental impact of nanotechnology. These studies will determine whether metallic nanoparticles are accumulated and transferred across trophic levels. The effects of long term exposure to copper, silver and titania nanoparticles in aquatic organisms will be identified as well as appropriate markers for their toxicity. Data will be developed that seeks to understand how particle mediated radical production is involved in toxicity. The experiments will evaluate the performance of several standard aquatic toxicity tests for use with nanoparticles and determine their suitability for this purpose.
Broader Impacts: This research will provide research training for post-doctoral researchers at the interface of particle science and biology. Investigators on this project are participants in the SEAGEP program and this will be leveraged to provide research opportunities for underrepresented minorities. In addition, the investigators plan to collaborate with other national resources in nanotechnology such as Center for Nanotechnology in Society at Arizona State University and ICON at Rice to disseminate research results to the scientific and educational communities and to society at large. Researchers will also work with the Graham Center for Public Policy at the University of Florida to ensure that research findings are translated to policy makers.
