Impacts of Manufactured Nanomaterials on Human Health and the Environment - A Focus on Nanoparticulate Aerosol and Atmospherically Processed Nanoparticulate Aerosol
|Principal Investigator||Vicki Grassian|
|Institution||University of Iowa|
|Relevance to Implications||High|
|Class of Nanomaterial||Engineered Nanomaterials|
|Impact Sector||Human Health|
|Broad Research Categories||
|Anticipated Total Funding||$335,000.00|
|Anticipated End Year||2007|
In this proposal, the potential effects of manufactured nanomaterial aerosol on human health will be investigated and compared to ultrafine carbonaceous particles typically found in the environment from combustion processes. This research will be conducted to satisfy three main objectives. These objectives are to:
1) fully characterize a variety of manufactured nanomaterials in terms of their size, shape, bulk and surface properties;
2) determine if engineered nanomaterials are particularly deleterious to health compared to particles from combustion processes that have been more extensively studied; and
3) evaluate the relative health effects caused by different surface coatings on the nanoparticle.
Manufactured nanomaterials will be purchased from several sources and further characterized using a wide variety of techniques and analysis methods including surface spectroscopy so that both bulk and surfaces properties can be understood on a molecular level. These well-characterized particles will then be used for inhalation and exposure studies using laboratory animals. There will be additional characterization once the aerosol has been generated to determine if the particles aggregate or retain the size distribution determined prior to aerosol generation. Toxicology assessments of the animals will include murine assays to screen for acute and sub-chronic pulmonary effects.
Manufactured nanomaterials will be purchased from several sources and further characterized using a wide variety of techniques and analysis methods including surface spectroscopy so that both bulk and surfaces properties can be understood on a molecular level. In going from the atomic/molecular level to extended bulk and condensed phases, physical and chemical properties are found to change as a function of size. A number of physical and chemical properties are size-dependent including: optical properties, melting point, magnetic moment, specific heat, morphology, crystallinity, phase, particle shape and surface reactivity. Thus it is important to fully characterize nanoparticles used in these studies. These well-characterized particles will then be used for inhalation exposure studies using rodents.
Inhalation exposures to aerosols are most often conducted with one of two methods, whole-body or nose-only exposure. “Whole-body” refers to traditional aerosol exposure studies involving sealed chambers in which the animals are placed in cages and allowed to naturally breath an aerosol. “Nose-only” refers to the use of a device that restrains the animal within an open-ended tube through which their snout protrudes. Aerosol-laden air then flows past the snout to induce exposure to the aerosol. Such a device better ensures inhalation of a known quantity of aerosol and typically requires less parent material as flow rates through a nose-only chamber are much smaller than those required for whole-body chambers. However, use of nose-only chambers requires pre-training the animals to reduce stress, and can elevate body temperatures if exposure periods exceed one to two hours. There will be additional characterization once the aerosol has been generated to determine if the particles aggregate or retain the size distribution determined prior to aerosol generation.
Few studies have been performed to determine a dose-response relationship associated with inhalation of nanoparticles. Given this lack of previous research, the biological mechanisms responsible for instigating airway reactivity are not known and a testable hypothesis is not yet attainable. Therefore, well-developed procedures available to screen for airway reactivity and inflammation will be used during this research to indicate the potential effects resulting from the inhalation of nanoparticles. These procedures will follow a three-part process including murine acute pulmonary inflammation assay, murine sub-acute pulmonary toxicology evaluation and murine microbial challenge host resistance evaluation.
It is expected that these studies will help answer questions as to the potential impact of manufactured nanomaterial aerosol on human health as there is clearly a lack of information in this regard. Two important factors of the proposed activities are the comparison of the potential health effects of manufactured nanomaterials to other anthropogenic sources of ultrafine particles from combustion processes and the effect of surface coatings, from manufacturing and atmospheric processing, on the toxicity of these particles.