Superfund Research Program
Nanoscale Materials in the Environment and their Health Effects
Project Leader: Ian M. Kennedy
Grant Number: P42ES004699
Funding Period: 2010-2015
Nano materials can appear in water systems and may affect aquatic animals and plants. The research team for this project exposed tilapia fish embryos to copper oxide nanoparticles and assessed their response. Researchers found that their response was sensitive to the salinity of their environment. Nano materials are often coated to improve their functionality and to minimize their toxicity. A common approach involves the use of oleic acid. Researchers found that a commonly reported coating can actually disintegrate during interaction with cells and lead to unexpected toxicity. The results indicated that care needs to be taken in the type of coating that is applied to nano materials. The research team has a system for determining the impact of nano materials on the function of human cells such as the lung macrophage. The macrophage makes use of its motility to take up foreign materials within the lung. It is hypothesized that nano materials may compromise this function. To this end, a system has been developed using polymer micro-pillars on which the macrophages are cultured. Deflection of the pillars gives a direct measurement of the traction force that the macrophage can apply to its surroundings in order to move.
Researchers are currently measuring the motility of macrophages with and without exposure to a variety of nano materials. An exposure system has been developed for animal studies looking at the toxicity of nano materials that are inhaled. This system provides a well-controlled environment of metal oxide nanoparticles that are doped with a fluorescent lanthanide element to permit imaging within tissues. Studies have been carried out using neonatal, juvenile and adult rats. These very sensitive measurements of the amount of deposition of nano materials show that the most vulnerable animals are the juvenile animals, in which the greatest amount of nano materials were deposited within the lung. This finding has significance for public health because juvenile humans typically will face the greatest exposure risk as they are most active outdoors, in some cases near roadways or other sources of nano materials.
Researchers have examined the ability of airborne particles, and individual particle components, to make reactive oxygen species (ROS) such as HOOH and OH. This is important because the generation of ROS has been linked to the toxicity of airborne particles, which kill approximately 100,000 people in the U.S. each year. Combining laboratory results of HOOH generation by individual redox-active metals and quinones with published concentrations of these species, has revealed that Cu accounts for nearly all of the HOOH generated by inhaled ambient particles. This suggests that copper plays a major role in the generation of oxidants by airborne particles and, possibly, in the toxicity that is associated with ambient particles.