This study reported that p53 heterozygous mice developed and died from peritoneal mesothelioma approximately 144 days following a single intraperitoneal injection of multiwalled carbon nanotubes (MWCNT) but not after treatment with fullerenes. The authors concluded that it would be prudent to implement strategies to keep good control of exposure to fibrous or rod-shaped carbon materials in the workplace until the biological properties and carcinogenic potential are fully assessed.  However, it is important to note that the route of administration was intraperitoneal and not inhalation and the mouse model used is susceptible to the development of tumors. 

The nanotechnology movement has been given a unique "window of opportunity" to systematically investigate the toxicity of nanotechnology products and to develop ways to manage health risks before large scale manufacturing becomes widespread.  

This study examines changes in brain activity, particularly in the frontal cortex, that result from exposure to diesel exhaust (DE), which is a mixture of non-engineered nanoparticles and exhaust compounds.  Further human studies are necessary to determine whether nanoparticles in DE are responsible for these effects and if so, by what mechanism.  

The authors discuss the appropriateness of establishing occupational medical surveillance programs for workers handling nanomaterials. Because there is no information yet available on health outcomes that may be associated with exposure to nanoparticles, the authors suggest general medical screening, baseline examinations, and establishment of exposure registries to document who is currently working with nanomaterials. 

The findings from this study indicate that following intravenous injection in mice, quantum dots may localize in important organs such as the kidney or liver, and they have a very long biological half-life. Such observations are important, given the potential for the use of quantum dots for biological imaging purposes in humans. 

This study indicates that the observed in vitro effects of nanoparticles are not necessarily predictive of in vivo pulmonary effects.  In vitro assays will need to be standardized and validated relative to in vivo effects before they can provide useful screening data on the relative toxicity of inhaled nanoparticles. 

It is uncertain if engineered nanomaterials may be toxic to cells and organisms, due to their extremely small nature (Less than 100 nanometers); therefore, it is necessary to develop and implement relevant regulations for public health policy.