iokinetics of Nano-sized Particles. While many uptake and translocation routes have been demonstrated, others still are hypothetical and need to be investigated. Largely unknown are translocation rates as well as accumulation and retention in critical target sites and their underlying mechanisms. These as well as potential adverse effects will be largely dependent on physicochemical characteristics of the surface and core of nano-sized particles. Both qualitative and quantitative changes in nano-sized particles’ biokinetics in a diseased or compromised organism need also to be considered.
The human exposure assessment is a multidimensional analysis. The assessment includes the likelihood of exposure, the magnitude of exposure, the relevant routes of entry into the body, and the populations that may be exposed. However, the relationship between all the exposure assessment variables is complicated as the life cycles of the exposed nanoparticles is complex (Figure 4). For example, it may be logical to assume that a worker in the nanomanufacturing plant may be at more danger because he will be exposed to more nanoparticles than a consumer of the nanoparticles product. However, workers may be exposed to higher concentrations of nanoparticles which may be elevated to the point of particle agglomeration into larger, and less toxic, particle entities; whereas at home while people may be exposed to lower concentrations, but the particles are discrete and therefore more toxic. And since smaller particle sizes of the same composition have been shown to be more dangerous, the consumer may in fact end up with a more serious health hazard at stake.