(Beyond Pesticides, August 12, 2011) Researchers have begun investigating silver nanoparticles, or nanosilver, in order to discover what exactly makes the particles toxic to the environment. Although scientists have long been concerned about the evidence of toxicity of nanosilver to both human health and the natural environment, research so far has been unclear on which properties of the particles actually make them toxic. The dangers may stem from the nanoparticles themselves, but they may also be due to the silver ions that the particles shed.
Previous attempts to distinguish nanoparticles from silver ions have proven unfruitful, as they have been unable to fully separate the two. However, a new method developed by researchers in China aims to use an older technique called cloud point extraction and apply it to the nanosilver in order to separate the ions from the particles. This will enable researchers to identify whether consumer products, as well as environmental samples such as wastewater, containing nanosilver actually contain nanoparticles or if they contain silver ions. The method will need to be refined further in order to adequately examine the very small nanosilver concentrations that are most often found in the environment, such as in wastewater or surface water, but scientists are hopeful that the new method will enable them to more accurately study the components of nanosilver and identify the trigger that makes it toxic.
Nanosilver, used as an antibacterial agent in many products, is much more toxic than regular silver and can cause damage in new ways. Concerns over nanosilver were first raised by national wastewater utilities in early 2006. A 2008 study shows that washing nanosilver socks 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.
Nanosized particles are super small particles with unique properties that are now incorporated in food production as well as into many consumer products including paper wrapping, clothing and cosmetics, are currently not regulated and have not yet been assessed for hazards that have the potential to impact public health and the environment. They are increasingly being used as pesticides as, due to their small size, these nanoparticles are able to invade bacteria and other microorganisms and kill them. As these tiny materials hit the market, there are huge gaps in what scientists know about their properties. Earlier this year, the California’s Department of Toxic Substances Control (DTSC) asked in-state nanotechnology companies and researchers to share how they are keeping tabs on several nano-sized metals, as evidence continues to emerge that these substances may have long-term implications for the environment. Some studies have shown that some of these nanomaterials are turning up in end-stage sewage sludge, raising questions about long-term environmental problems. Other nanomaterials can be making their way to the water supplies.
Nanotechnology is a powerful new platform technology for taking apart and reconstructing nature at the atomic and molecular level. 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. Scientists and researchers are becoming increasingly concerned with the potential impacts of these particles on public health and the environment. A study by scientists from Oregon State University (OSU) and the European Union (EU) highlights the major regulatory and educational issues that they believe should be considered before nanoparticles are used in pesticides.
At its October 2010 meeting, the U.S. Department of Agriculture’s (USDA) National Organic Standards Board (NOSB) passed a recommendation directing the USDA National Organic Program to prohibit engineered nanomaterials from certified organic products as expeditiously as possible. The NOSB, the expert citizen advisory panel set up by Congress to advise the USDA on organic policy, reviews materials and provides recommendations to the NOP on what should be allowed and prohibited in organic agriculture and processing, as materials and methods change over time. Organic advocates, members of the organic industry and the NOSB are concerned that engineered nanomaterials could contaminate organic food and fibers.
Source: Chemical & Engineering News