(NHI Nanoblog) Does breathing in super-small particles of carbon and silica lead to the same kind of health problems caused by smoking or smog? Researchers in Ireland and the United States think they’ve found a reason to think it might.
Scientists at Trinity College Dublin and the U.S. National Institute for Occupational Safety and Health just published the study, which used human lung cells and mice to gauge the impact of carbon black, single-walled carbon nanotubes and nano-sized silicon dioxide particles (click here to read it). They found that exposure to the nanoparticles sparked the same response in both human cells and rodents: the amino acid arginine morphed into citrulline.
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The process is called protein citrullination.
That’s important because the proteins that use this now-modified amino acid as building materials instead get broken down by the body. According to the study’s authors, that can trigger an attack from the immune system, prompting autoimmune responses that cause conditions such as rheumatoid arthritis.
In a Trinity College press release, one of the study’s lead authors, Yuri Volkov, says these findings might be especially useful in helping scientists devise ways to stop or reverse the process that leads to autoimmune responses.
Does this paper say nanoparticles cause arthritis? No. But it does add a new wrinkle to the discussions over the safety of some ultra-tiny materials — especially those that are smaller versions of substances already considered questionable, including carbon and silicon dioxide.
Nanotechnology is a broad term that encompasses a wide variety of uses of very small materials. (A nanometer is a billionth of a meter.) These substances can make better batteries or lighter and stronger bike frames, as well as new medical instruments and medicines that can save lives. They’re increasingly common in consumer products, from sunscreens to stain-repellent pants to boat paints that resist algae growth.
Nanomaterials are believed to hold great promise for a wide variety of applications. Their ultra-tiny size often gives them different properties, which is the basis of their appeal; scientists are struggling to figure out whether that can make them dangerous in the process, and how and why it happens.
In many ways, it’s not at all surprising that carbon- and silica-based nanoparticles cause what’s essentially an inflammatory response in the lungs. Scientists know occupational exposure to silica dust can cause silicosis, and think it may lead to other conditions, including cancer and autoimmune disorders.
Soot has been linked to cancer as well. Carbon nanotubes have drawn attention because of research showing they can get into the same space in the lungs where mesothelioma, the disease most associated with asbestos exposure, can occur. NIOSH issued a draft recommendation for workplace exposure to carbon nanotubes and nanofibers that is effectively zero, urging employers to take precautions.
What studies like this one don’t tell us, however, is how likely it is that any of us will suffer health problems because of exposure to these types of nanoparticles. As Dexter Johnson points out on his Nanoclast blog, few scientists are studying exposure to nanomaterials from the actual products they’re going into — a big part of answering safety questions about these substances.
Carbon nanotubes, for example, are often used to strengthen composite materials, meaning they’re deeply enmeshed in, for example, a bike frame. That probably means little chance of exposure — and therefore little risk — to the average cyclist. The pressure points may be at the beginning of the bike’s life (through occupational exposure) and the end (when the frame hits the landfill or the incinerator).
Click here for more Independent articles on nanotechnology.