This image of toxic effects from exposure to nanoparticles dates to 2007. New nanotoxicological techniques could mean significant changes to the diagram, but in surprising ways. Credit: Wikimedia.
As nanotechnology is increasingly commercialized, the question of safety, as it relates to handling the materials during synthesis and manufacture, and even in product use, arises regularly.
The National Institute for Occupational Safety and Health (NIOSH), a branch of the Centers for Disease Control and Prevention, has the issue on their radar. According to its website, NIOSH has identified 10 critical areas that it wants to “guide in addressing knowledge gaps, developing strategies, and providing recommendations,” and it is backing it up with research on the nanomaterials in the workplace. The 10 areas are toxicity and internal dose; risk assessment; epidemiology and surveillance; engineering controls and personal protective equipment; measure methods; exposure assessment; fire and explosion safety; recommendations and guidance; communication and information; and applications.
A big problem is that it is not easy to observe how nanoparticles interact with human physiology, in part because they are so small and, because of this, analytical techniques are difficult to develop. For example, a while back we reported on research on whether zinc oxide nanoparticles in sunscreen might be a health hazard. In this work, investigators used nonlinear optical microscopy to directly measure ZnO nanoparticle uptake in the deep layers of human skin-those that underlie the stratum corneum surface layer.
This week, the American Chemical Society (ACS) is holding its 245th national meeting (congratulations, ACS!) in New Orleans. This year’s theme—Chemistry of Energy and Food—explores the relationship, of course, between chemistry and food. This year is the first year for a new ACS lecture, the Kavli Foundation Emerging Leader in Chemistry Lecture. The lecture, delivered on Monday by Christy Haynes of the University of Minnesota, was titled “Biological and ecological toxicity of engineered nanomaterials.” According to the ACS website, Haynes is among the first to use a specialized technique to study the effect of nanoparticles on cells called “carbon-fiber microelectrode amperometry,” which is used in medicine to study sickle cell anemia, endocrine chemistry, etc.
According to an ACS press release, Haynes says more than 800 consumer products involve nanotechnology and has given rise to the new field of “nanotoxicology.” Initially, she said in her lecture, attempts were made to infer nanotoxic effects based on analytical tests developed for bulk materials. However, as is known now, nanoparticles behave very differently from bulk particles—and not just in the body. The interest in nanoparticles as engineered materials for things like supercapacitors derives from their unique size-related properties.
Haynes said in her lecture, “a nanoparticle of material used in food or a cosmetic lotion may contain just a few atoms, or a few thousand atoms. Regular-sized pieces of that same material might contain billions of atoms. That difference makes nanoparticles behave differently than their bulk counterparts.”
Early toxicology tests, she said, were simple: Did cells growing in a laboratory culture live or die after being exposed to a nanoparticle? However, such a simple approach did not account for two important factors. First, Haynes said, “A cell can be alive but unable to function properly, and it would not be apparent in those tests. Second, nanoparticles are more highly reactive (again, an attractive, “engineerable” property), which can cause “false positives” and make nanoparticles appear more toxic than they are.
Researchers in Haynes’ lab are working on tests to determine whether “key cells in the immune system can still work normally after exposure to nanoparticles.” Also, they are using bacteria to probe whether cells exposed to nanoparticles can maintain the “biochemical chatter” that is essential.
Haynes leads the University of Minnesota’s contribution to the multi-institutional, NSF-funded Center for Sustainable Nanotechnology. Located at the University of Wisconsin-Madison, the center is “devoted to investigating the fundamental molecular mechanisms by which nanoparticles interact with biological systems.”