by RTT Staff Writer
The researchers looked at five types of engineered, industrially-used nanoparticles – silver, zinc oxide, iron oxide, cerium oxide, and silicon dioxide. These nanoparticles produce free radicals, called reactive oxygen species, that can alter DNA.
The zinc oxide nanoparticles often found in sunscreen to block ultraviolet rays, and the nanoscale silver used in toys, toothpaste, clothing and other products for its antimicrobial properties were found doing substantial DNA damage.
But what is the consequence of this DNA damage? While it may not necessarily kill a cell, the researchers say it can lead to cancerous mutations if the damage is not repaired.
On the other hand, silicon dioxide, a common additive found food and drugs, had little adverse impact on DNA. Iron oxide and cerium oxide also showed low genotoxicity.
The researchers tested the effects of nanoparticles on human blood cells lymphoblastoids and Chinese hamster ovary cells.
While more are necessary to see how much exposure to metal oxide nanoparticles is unsafe, children and fetuses could be at greater risk as their cells divide more often, making them more vulnerable to DNA damage.
The most common points of entry for engineered nanoparticles are the skin, lungs and stomach. One of the areas of greatest concern is occupational exposure to nanoparticles, the researchers say.
While several studies have shown that these engineered nanoparticles can be toxic to cells, researchers say that few studies have looked for the ability of nanoparticles to damage DNA.
They are also studying the effects of other engineered nanoparticles that can become airborne and enter the lungs, such as the metal oxides used in printer and photocopier toner.
The study, published recently in the journal ACS Nano, employed a high-speed screening approach that uses microfabrication technology to process samples at a rate and larger scale than before. The researchers hope this approach will assist in designing safer forms of nanoparticles.
Perhaps their hopes are well-founded, as it has been recently demonstrated in Philip Demokritou’s lab that applying a nanothin coating of amorphous silica to zinc oxide particles can mitigate their harmful impact on DNA.
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