An image of carbon nanotubes interacting with cells. Research has shown that these cylindrical tubes can wreak havoc with cells and have a detrimental affect. Cells ingest things by engulfing them. When a long cylindrical fibre like a carbon nanotube comes near, the cell senses only its tip, mistakes it for a sphere, and begins engulfing something too long to fully ingest.
Credit: Gao Lab/Brown University
Nanotechnology, the science of manipulating tiny particles less than 100 nanometers in diameter, has found many applications in consumer products, biomedical devices, drug delivery agents and the industrial sector.
In the consumer sector alone, more than 30 countries are manufacturing some 1,300 nanotech-based products, including textiles, food packaging, cosmetics, luggage, children's toys, floor cleaners and wound dressings. The number of such products has increased five-fold in the last five years.
But this rapid growth has also raised concerns about the potential for adverse effects on human health and the environment. Although research on harm remains inconclusive, developing countries that embrace nanotechnology should not overlook possible risks and must regulate products that contain nanoparticles.
Their small size gives nanoparticles some unusual physical properties, as they have a larger ratio of surface area to volume than bigger particles. This can also make them biologically more active. For example, when gold, usually an inert material, is converted to a nano-form, it acts as a catalyst for chemical reactions owing to high surface reactivity.
This suggests that nanoparticles may interact differently with biological systems, compared with larger particles, and could reach further into the body.
People can be exposed to nanoparticles either directly, such as through nano-based drugs and topically applied cosmetics or sunscreens, or indirectly, for example by inhalation during synthesis of nanoparticles.
A number of studies have documented in vitro and in vivo toxicity of exposure to nanoparticles. Evidence suggests they can induce DNA damage, reactive oxygen species, damage to cellular organelles and cell death.
And a study published in the European Respiratory Journal in 2009 claimed that seven Chinese workers developed severe lung damage after inhaling polyacrylate nanoparticles produced in their printing factory - the first time that a link was made between exposure to nanoparticles and human illness.
There is currently no mandatory consumer labelling of nanomaterials as potentially hazardous in any country. But governments and scientific bodies in the developed world - including the Royal Society, United Kingdom, and the U.S. Environmental Protection Agency (EPA) - are taking note of the potential hazards and have set up committees to formulate risk assessment guidelines.
For example, under existing regulations, the EPA is proposing rules requiring those that manufacture, import or process two chemical substances - multi-walled and single-walled carbon nanotubes - to submit a notice with information that would help it monitor health or environmental risks.
Similarly, washing machines using silver nanoparticles at the end of the wash cycle are being evaluated by the U.S. government for their environmental safety. In 2005, concerns about toxic effects on microbe populations prompted the temporary withdrawal of a washing machine using silver nanoparticles in Sweden.
The U.S, EPA has already decided to regulate products containing silver nanoparticles, which are used widely in consumer products and have anti-bacterial properties.
