Read the following interesting, concise and relevant account on the effect of exposure of nano materials on human body presented as such.

As with all chemical manufacturing processes, production of NPs may give rise to exposure by inhalation, through the skin and by ingestion. Exposure may also occur for workers in downstream processes that use these materials and to consumers as these products enter the market-place. In gas-phase production processes, exposure by inhalation may be caused by direct leakage of the reactants or products into workplace air. For all production methods, product recovery, subsequent processing and cleaning may result in the generation of airborne NPs. It is, however, probable that these downstream activities will not generate discrete NPs, due to the relatively high energies, which would be necessary to break the forces which keep particles agglomerated. However, exposure to agglomerated NPs may also pose a significant risk to health. All the production processes described could potentially result in dermal exposure, particularly at the powder handling, packaging and bagging stages. It has been postulated that NP exposure to the skin may result in direct penetration, although currently there is little evidence to support this. Several pharmaceutical companies are, however, developing drug delivery systems based on topical application NPs. Dermal exposure is likely to result in ingestion exposure from hand-to-mouth contact. Typically, airborne exposures in the workplace are assessed in terms of mass concentration. Current evidence suggests that the most appropriate metric for exposure by inhalation for NPs is surface area. This appears to fit best with current toxicological evidence relating to mechanisms of harm. It would also address directly the issue of agglomeration. Ideally a personal sampler should be available which could assess this metric. However, none currently exists. For those NPs that could be considered as fibers, such as CNTs, particle number may be a more appropriate metric than surface area. In any case, it is also necessary to consider characterizing exposures against aerosol mass and number concentration until further information and improved methods are available. For each of these exposure metrics, but particularly in the case of mass concentration, size-selective sampling will need to be employed to ensure only particles within the relevant size range are sampled. For dermal exposure, measurements should also be biologically relevant. At this stage, there is insufficient evidence to indicate whether mass, number or surface area is the most appropriate metric. Measurement approaches should ideally also consider the skin area exposed and the duration of exposure. For ingestion exposure too, measurements should also be biologically relevant. There is insufficient evidence to indicate what the most appropriate metric is. Information about the exposure of workers to NPs is very limited. None has been identified about exposures in the university/research sector or in the new NP companies. Very limited information is available on existing chemical, pharmaceutical and refining companies. Either mass or number is used as an exposure metric, rather than surface area. The number-based estimates are derived from static samplers rather than personal samplers. Information from other powder-handling processes indicates that exposures may be significant. There is a clear need to collect more information about exposure to NPs in both manufacturing and user scenarios. Production quantities are still relatively small. As products grow in both number and volume, and as manufacturers switch process from the micro- to the nanoscale, the potential for exposure will clearly increase. Much more information is needed to quantify any risks to workers or consumers.
Source: R. J. Aitken, M. Q. Chaudhry, A. B. A. Boxall and M. Hull. Manufacture and use of nanomaterials: current status in the UK and global trends, Occupational Medicine 2006;56:300–306 doi:10.1093/occmed/kql051