From water-repellant fabrics to more effective sunscreens, nanotechnology has become increasingly commonplace. However, because nano-objects have different properties from their larger counterparts, nanotoxicological studies must be carried out to determine whether they pose a threat to human health. Although some forms of nanotechnology have been well-studied and are known to be safe, others require more research before we can determine whether they are toxic and how to use them safely.
Did You Know? A nanometre is a hundred-thousandth the width of a human hair.Compared to larger objects, nano-objects have a much larger surface area relative to their volume. As a result, a person who absorbs equal amounts of both a “normal” compound and a nano-object will come into contact with more molecules of the nano-object. This means that the results of conventional dose-response relationship studies, conducted on traditional substances, may not be accurate for similar nano-objects.
Additionally, harmful chemical and physical effects that are not caused by larger particles may occur at the nano scale. A nanoparticle can even be toxic in one configuration but not in another. For example, when carbon is in the form of a diamond nanoparticle, it is harmless. But carbon in the form of nanotubes may cause health problems, depending the nanotubes' length and degree of aggregation (the extent to which nanoparticles have “clumped” together).
Did you know? Dose-response relationship studies examine how the toxicity of something varies with concentration.One study has looked at the similarity between nanotubes and the needle-like shape of asbestos fibres. Asbestos has been linked to many serious health problems, including lung cancer, so researchers were concerned that exposure to nanotubes could result in similar diseases. The study found that exposing the abdominal cavity of mice to nanotubes resulted in asbestos-like, pathogenic behaviour.
Although not all forms of nanotechnology have been properly studied, some products that we use every day contain nanoparticles and are known to be safe. For example, many sunscreens now contain nanoparticles of titanium oxide or zinc oxide. These particles don't leave the whitish residue that older sunscreens did, and they are more effective at blocking UVA and UVB rays. Numerous studies have monitored the safety of these sunscreens, and it has been concluded that nanoparticles cannot enter through the outer layer of a healthy person's skin.
Did you know? Nanotubes are one-atom thick sheets of carbon that have been rolled into tubes.But more research needs to be carried out before we know how other forms of nanotechnology affect the body, and at what doses. Nanovalid, a four-year project involving 29 partners from across the globe, is currently assessing the risk of nanotechnology by developing reliable test methods. Projects like this one will allow researchers to reliably assess different forms of nanotechnology on a case-by-case basis.
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