(Beyond Pesticides, May 3, 2012) Scientists at the University of Maryland School of Dentistry have created the first cavity-filling composite using controversial nanotechnology that will both kill bacteria and regenerate tooth structure. The antibacterial component to the new fillings will be a base of quaternary ammonium and silver nanoparticles, along with a high pH.
Researchers say that the nanocomposite filling will be able to neutralize residual bacteria that dentists are unable to remove after a dentist drills out a decayed tooth. Though nanotechnology is often heralded for its promising applications, scientists and researchers are becoming increasingly concerned with the lack of regulatory oversight and the potential impacts of these particles on public health and the environment.
In addition to testing in animal teeth, the products will be tested in human volunteers in collaboration with the Federal University of Ceara in Brazil. So far, the products have been laboratory tested using biofilms from saliva of volunteers. In 2011, the U.S. Environmental Protection Agency (EPA) took several actions to limit human testing with strict guidelines. Human testing was initially stopped by a moratorium in 1998, but later reintroduced in 2003 by a court ruling on a pesticide industry suit.
A silver nanoparticle consists of many silver atoms or ions clustered together to form a particle 1-100nm in size. Due to their small size, these nanoparticles are able to invade bacteria and other microorganisms and kill them. Just as the size and chemical characteristics of manufactured nanoparticles can give them unique properties, those same new properties —tiny size, vastly increased surface area to volume ratio, high reactivity— can also create unique and unpredictable human health and environmental risks.
A study conducted in 2008 and confirmed by another study in 2009 shows that washing nano-silver textiles releases substantial amounts of the nanosilver into the laundry discharge water, which will ultimately reach natural waterways and potentially poison fish and other aquatic organisms. A study found nanosilver to cause malformations and to be lethal to small fish at various stages of development since they are able to cross the egg membranes and move into the fish embryos. A 2010 study by scientists at Oregon State University and in the European Union highlights the major regulatory and educational issues that they believe should be considered before nanoparticles are used in pesticides.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.