Their tiny size and high surface area give them unusual characteristics: insoluble materials become soluble; nonconductive ones start conducting electricity; harmless substances can become toxic. Nanoparticles are easily inhaled. They can pass from the lungs into the bloodstream and other organs. They can even slip through the olfactory nerve into the brain, evading the protective blood-brain barrier. The tiny cylinders known as carbon nanotubes, or CNTs, are among the most widely used nanomaterials.
These tubes, which come in different sizes and shapes, lend extraordinary strength and lightness to bicycle frames and tennis rackets; researchers are also investigating uses in medicine, electronics and other fields. The recent UK study found that long, straight CNTs, when injected into lab mice, cause scarring even faster than asbestos.
One of the investigators predicts the scarring will lead to cancer; other experts are less sure. But which workers want to serve as the test cases? Another red flag is silver. Manufacturers are lacing ordinary household objects — from toothpaste to teddy bears — with nanoparticles of silver, long known for its disinfecting powers.
A recent experiment on nanosilver-containing socks, touted as odor-eating, found that silver particles leaked out into the wash water. Once there, the silver could interfere with water-treatment efforts, in part by killing good microbes as well as the nasty ones, and might threaten aquatic life a fear supported by the zebrafish study.
When Samsung started marketing a washing machine that emits silver ions two years ago, a national association of wastewater treatment authorities asked the U. Now, that actually may be a good thing in parts of the body, but in the lungs you end up using up the air space. AM: Clearly there is joint responsibility between government and industry.
Do you think the existing federal regulatory agencies, like the EPA, can do it? The thing that concerns me is, there is very much a mind-set that is based on the conventional understanding of chemicals. But nanomaterials are not chemicals.
They have a structural component there as well as a chemical component. TR : You talked about developing smart sensors that measure not only the number of particles in the air that a worker might inhale, but also harmful effects.
You could imagine 10 to 20 years from now. What if you had a little sensor that you could put on your body that began to flash if there was a possibility of having a hazardous exposure? TR : You also say the Internet can help researchers coordinate their efforts. AM: The beauty of the Web is you can use it in innovative ways to summarize information and to provide portals for information. AM: The Wikipedia idea is something that has been talked about.
And I think that either that or something like that is a very exciting idea. TR : Has anyone actually looked into establishing a sort of nanowiki? AM: Not to my knowledge. Anatomy and physiology. The available evidence indicates that nanoparticle sunscreens are both effective and safe The applications for engineered nanomaterials and nanotechnology are developing exponentially, along with the awareness in government, industry and public groups of nanosafety issues.
View this article on Wiley Online Library. Competing interests:. Safety of engineered nanomaterials and occupational health and safety issues for commercial scale production.
Handbook of clinical nanomedicine: law, business, regulation, safety, and risk. Singapore: Pan Stanford Publishing, ; pp Nanobionics: the impact of nanotechnology on implantable medical bionic devices. Nanoscale ; 4: Opinion on nanosilver: safety health and environmental effects and role in antimicrobial resistance approved 10 June Luxembourg: European Commission, Scientific Committee on Consumer Safety.
Berube DM. Rhetorical gamesmanship in the nano debates over sunscreens and nanoparticles. J Nanopart Res ; UV absorption and scattering properties of inorganic-based sunscreens. Int J Cosmet Sci ; Barker PJ, Branch A. The interaction of modern sunscreen formulations with surface coatings.
Prog Org Coat ; Small amounts of zinc from zinc oxide particles in sunscreens applied outdoors are absorbed through human skin. Toxicol Sci ; Dermal absorption and short-term biological impact in hairless mice from sunscreens containing zinc oxide nano- or larger particles. Nanotoxicology ; 8 Suppl 1: Therefore, we cannot be sure that our body have developed defense mechanisms to deal with them.
A: Nanowires, and all other kinds of nanomaterials, can potentially enter our body in three ways: through the skin, through the gastrointestinal tract, or through inhalation. Based on current knowledge, the most important exposure route for nanoparticles is inhalation. It is unlikely that nanoparticles would penetrate healthy skin, still, it is a good idea to wear protective gloves e.
To avoid exposure through the gastrointestinal tract, food and drinks should never be ingested in the same laboratory or room as nanoparticles are handled. If inhaled, nanoparticles have a high probability of deposition in the lungs. How much is deposited depends on particle properties such as size, and physiological factors such as oral or nasal inhalation and exercise or rest..
Whilst impaction and interception are factors that are more dominant for micro-sized particles, nanosized particle depositions are more driven by diffusion in particular at low air speed, such as in the alveoli and surface charge. An important consideration in the deposition of particles in the respiratory system is the lung-lining fluid a complex mixture of lipids and surfactant proteins since any depositing material quickly becomes coated in these surfactant proteins and lipids.
This so-called protein corona, which is likely to play a role in the way particles interact with lung cells such as alveolar macrophages. If deposited in the deeper part of the lung, the alveoli tract, they are cleared either by the macrophages engulf particles that are deposited in the alveolar tract, and if they fail in doing this, the particles can be translocated from their primary organ of entry the lung to a secondary organ via the circulatory system.
In the tracheobronchial tract, particles are cleared by the mucociliary elevator, which transports particles up to the pharynx, after which they are swallowed and thereby enter the gastrointestinal tract. Among other parameters, the translocation rate and fraction to other organs depend on particle size, morphology, surface parameters such as composition, charge, and primary and secondary coatings with proteins, lipids and functional groups.
Inhaled nanoparticles can also translocate along sensory neuronal pathways to reach secondary organs and tissues such as the vascular endothelium, the heart and the brain. A: A higher physical activity leads to a higher breathing frequency and thereby a larger number of inhaled particles per unit time.
This in combination with that the lungs of children are under development and that children have less understanding for what potential dangers to avoid, makes children more susceptible than adults when it comes to all kinds of particle exposures.
A: Occupational exposure of nanoparticles can occur in three ways: by inhalation, by ingestion, or by skin penetration. The most common, and thereby most important route is by inhalation. It is likely that exposure of nanoparticles involves certain risks. The toxicity of nanomaterials can vary from those that are non-toxic or slightly toxic to those that are highly toxic. Fiber-shaped nanoparticles are often considered especially toxic, and animal studies have shown that some are even carcinogenic.
The precautionary principle should always be applied as long as the specific toxicity is not fully evaluated and as long as there are no nanospecific occupational exposure limits.
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