Can existing South African air quality standards be applied to nanoparticles?

Abstract

Particulates less than 100 nm (in at least one diameter) are referred to as nanoparticles. The properties of nanoparticles may differ from those of larger particles from the same bulk material. These unique properties allow the use of nanoparticles for specific applications such as drug delivery within the human body, or to enhance or replace existing materials. For example, carbon nanotubes are six times stronger than steel. There is therefore a need for intentionally manufactured (engineered) nanoparticles. The manufacture and use of these particles will however inevitably lead to their release into the environment (air, water and soil). A primary concern is that very little is known about the effects of these nanoparticles on human health and the environment, especially because of their unique properties. An in vivo study was conducted by the CSIR at the University of Pretoria Biomedical Research Centre at Onderstepoort, using the BALB/c murine model and nanoparticles engineered at the CSIR. These particles were engineered from titanium dioxide through a hydrothermal process, using potassium hydroxide. Animals were exposed to different concentrations of these particles in a whole-body inhalation chamber. The main aim of this study was to assess the degree of change, if any, to the weight, blood, and normal microscopic morphology of some organs, including the lungs. The findings of the study indicate that existing air quality standards may not be adequate to protect human health following exposure to specifically engineered nanoparticles