Today, Kimbrell and Salvi weigh the possible drawbacks of nanotechnology. Previously, they defined the scope of nanotechnology. Later in the week, they'll discuss government regulation, the future of nanotech research and more.
An unprecedented ability to harmBy George A. Kimbrell
This is a very broad question. I'll touch on three important areas of risk: the public, workers and the environment.
First, there is much more that we do not know about nanomaterials and their risks than what we do know. Despite rapid nanomaterial commercialization, many potential risks remain dangerously untested due to the failure to prioritize and fund risk research.
That said, there are also numerous foreseeable risks that arise from the fundamentally different nature and properties of nanomaterials. While not all nanomaterials will be found to be toxic or dangerous, they are also not uniformly safe, and crucially, their safety cannot be assumed from the testing of their bulk material counterparts. Just as the size and physics of nanomaterials give them unusual strength and reactivity properties, those properties also give them unpredicted risks such as increased toxicity and extreme mobility. And the limited existing risk studies continue to raise red flags, a few of which I will mention below.
Due to their tiny size, nanomaterials have unprecedented mobility for a manufactured material and can cross biological membranes, cells, tissues and organs more easily than larger particles. When inhaled, they can go from the lungs into the blood system. Once in the bloodstream, nanomaterials can circulate throughout the body and can lodge in organs and tissues such as the brain, liver, heart, kidneys, spleen, bone marrow and nervous system. The jury is still out on the ease of their skin penetration. The increased surface area of nanoparticles creates increased reactivity and enhanced intrinsic toxicity. Once inside cells, they may interfere with normal cellular function, cause oxidative damage and even cell death.
The public is exposed to manufactured nanomaterials in consumer products, like the many personal care, cosmetics and sunscreen products containing nanomaterials. These are "free" nanoparticles in a cream or gel that are used daily and placed directly on the skin. Studies have shown nanoparticles of titanium dioxide and zinc oxide used in many nano-sunscreens have to be photoactive, producing free radicals and causing DNA damage to human skin cells. Carbon fullerenes are being used in some face and anti-aging creams even though they are toxic to human liver cells at low levels.
There is no method currently for limiting, controlling or even measuring exposure to nanomaterials in the workplace. Dangers to workers could come from inhalation (the new asbestos?), access through the skin and digestive system (and the creation of free radicals that cause cell damage), or through the exposure to a new nanotech-created substance to which the body has no natural immunity or that triggers autoimmune disorders. Carbon nanotubes in particular have been likened to asbestos fibers and found to cause lung inflammation.
Manufactured nanomaterials are entering the natural environment throughout their lifecycle: manufacturing, transportation, use and disposal. Once loose in nature, these nanomaterials represent a new class of manufactured non-biodegradable pollutants. Nanomaterials' unique chemical and physical characteristics create various foreseeable environmental risks, including potentially toxic interactions or compounds, the absorption and/or transportation of pollutants, durability or bioaccumulation, and unprecedented mobility in ecosystems for a manufactured material. Studies have found carbon fullerenes to cause brain damage to fish and be toxic to other aquatic life. Nano-silver is currently being infused into a wide range of goods, including cleaning products and food packaging for its highly efficient antimicrobial properties. Yet the same properties that make these nanoparticles attractive to manufacturers are highly destructive to microorganisms once released into ecosystems.
George A. Kimbrell is staff attorney for the International Center for Technology Assessment, where he works on legal and policy issues related to nanotechnology, biotechnology and climate-change technologies.
Fake fears shouldn't stop progressBy Aatish Salvi
Before responding to this question, it is useful to step back for a moment and try to put the question into perspective. Technological innovation is inevitable, and nanotechnology is the next step. A more appropriate question is what have we learned over the course of technological innovation that will ensure nanotechnological innovation is developed prudently and in a way that achieves all that we believe it will.
We have learned much about the responsible development of technologies, which serves society well in commercializing nanotechnology. To date, for example, there have been no reported problems associated with any products using nanotechnology. This is because manufacturers are applying their risk mitigation and best practices consistently and responsibly.
One cannot draw general conclusions about the risks of nanomaterials, let alone nanotechnology. The risks will depend on how we make specific products using nanotechnology and how we use them.
George, you conclude that nanomaterials have enhanced intrinsic toxicity based on one variable size. I have not seen a single scientific study to support that claim. In fact, studies have shown size is not the sole driver of hazard and is generally thought to be less important than surface properties.
Sunscreen's use of zinc oxide and titanium dioxide nanoparticles has become a hot-button issue. You claim that these particles produce free radicals "causing DNA damage to human skin cells." Natural sunlight also causes DNA damage to skin cells, which is why we wear sunscreen. The World Health Organization estimates that cancers resulting from ultraviolet sun light exposure cause 60,000 deaths annually. The Environmental Working Group evaluated more than 900 sunscreens; of the top 100, 94 contained zinc oxide and titanium dioxide. It concluded: "Zinc oxide and titanium dioxide are stable compounds that provide broad spectrum UVA and UVB protection, while the available studies consistently show very little or zero penetration of intact skin by these compounds, indicating that real world exposure to potential nano-sized particles in these products is likely very low (Borm 2006). The sun protection benefits, in contrast, are very high."
George, your statement that "there is no method currently for limiting, controlling, or even measuring exposure to nanomaterials in the workplace" is simply wrong. Engineering controls (for examples, manufacturing in enclosed environments) can greatly reduce or nearly eliminate exposure. Furthermore, the National Institute for Occupational Safety and Health (NIOSH) has found that wearing personal protective equipment such as face masks prevent more than 99% of nanomaterials from entering the body.
NIOSH also has visited nanomaterial manufacturers to quantify workplace nanoparticulate matter. In most of these facilities, the primary source of nanoparticulate matter is not the manufacturing process but emissions from the facilities' furnaces. In some cases, urban air contains more nanoparticles than air inside the manufacturing facility.
George, you also say that nanomaterials have "unprecedented mobility" and might find their way into biological places that their larger counterparts cannot penetrate. Your observation neglects to note that certain nanoscale materials are designed to achieve this result. Cancer victims hopethat nanoscale materials will travel to new biological frontiers and deliver cancer-curing relief. As for other engineered nanomaterials, your statement neglects to note that these materials are produced in controlled environments, under specific circumstances and for specific applications.
Nanotechnology companies are committed to ensuring the safety of nanotech-enabled products. Such companies are taking proactive steps to ensure the safety of their workers, the public and the environment. They are partnering with NIOSH to develop data on workplace exposures; participating in the Environmental Protection Agency's Nanomaterials Stewardship Program to provide data on the existing nanomaterials in commerce; and practicing good product stewardship.
Nanotechnology is already demonstrating that it will provide significant benefits to the public, our nation and the environment. We should not let generic fear of "nanotechnology risks" prevent us from harnessing this new frontier of innovation to create real products that provide compelling real-world benefits. More to come tomorrow
Aatish Salvi is vice president of the NanoBusiness Alliance.