June 28, 2007

Are nanomaterials another environmental worry?

  • Researchers are generating more data on nanomaterial toxicity, but not all the tiny particles behave the same.


    Electronics are getting smaller and smaller, as exemplified in the diminutive sizes of our cell phones and iPods. This trend is due in part to nanotechnology, that is, the use and production of materials smaller than 100 nanometers in diameter. To state it simply, nanoparticles are really small; for comparison, the width of a human hair is about 80,000 nanometers. Nanomaterials also behave differently than larger particles; for example, we know gold to be a familiar yellow color, but nanosized particles of gold are red.

    Nanotechnology spans many different fields, from electronics to clothing to medicine and cosmetics. Its presence in our modern lives is all but inescapable.

    Nanoparticles are ubiquitous; however, the increased sensitivity of measurement equipment is only beginning to reveal the extent. Nanosized particles are produced by fuel combustion, the grinding of larger materials, or the specific arrangement of individual atoms. They are in our sunscreens, our stain-resistant shirts and our house paint. The Woodrow Wilson Institute Project on Emerging Nanotechnologies estimates that nearly 500 nanotechnology products are on the market.

    Environmental health and safety issues related to nanomaterials are gaining increased attention. Regulatory agencies, as well as the media, have shifted focus from initial euphoria about the potential of nanotechnology to concern about the safety issues related to nanomaterial production.

    Uncertainty about the health impacts associated with nanotechnologies and the industry’s potentially uncontrolled growth has resulted in calls from environmental and political bodies for such extreme measures as banning or limiting nanomaterial use or for increasing stringency in government regulations. However, the Woodrow Wilson Institute notes that in 2005, nanotechnology was used in more than $30 billion of manufactured goods and Lux Research, an emerging technologies research firm, expects this number to grow to $2.4 trillion by 2014. The key is to find a way to encourage the growth of the industry without compromising human and ecological health.

    Nanotech in Washington

    The greater Puget Sound area has a growing nanotechnology sector. The effort is led by the Center for Nanotechnology at the University of Washington, Washington Technology Center’s Nanotechnology Initiative, as well as industry leaders Carbon Nanoprobes, Lumera Corp. and Nanostring Technologies. Just as the greater Seattle area has become a leader in biotechnology, these groups and others will lead the growth of the local nanotechnology industry. The Woodrow Wilson Institute lists the Seattle area as one of the top 10 “NanoMetro” areas in the country.


    The production of novel nanoparticles holds great promise in that developers can manipulate the particles’ characteristics. Certain nanoparticles can possess intriguing characteristics that larger particles of the same composition do not, such as conductivity or enhanced strength. This allows the production of cancer medications that directly target cancer cells without damaging nearby cells and bulletproof vests that are stronger, lighter and more resilient. Because of the ability to manipulate the atomic structure and composition of nanoparticles, nanomaterials can be better, faster, stronger, longer lasting and safer than conventional materials.


    The human health and ecological risks of nanomaterials are largely unknown. Because of their small size, nanoparticles may behave differently than larger particles of the same composition. In many cases this is beneficial, but it may be the cause of toxicity as well. Extremely small particles may access different parts of the body than larger particles, gaining access to cellular organelles, being taken up by neurons, and evading the immune system.

    Although many uncertainties exist, researchers are generating increasing data on nanomaterial toxicity. It will not be possible to craft a blanket statement on the toxicity of all nanomaterials. Rather, different types of nanoparticles will require individual evaluation to ascertain the appropriate amount of protection.

    Protecting the environment

    For many chemicals and contaminants, regulations are in place to control releases and prevent adverse effects on humans, animals and the ecosystem. For larger particles and chemicals, the Environmental Protection Agency, state agencies, and the Occupational Health and Safety Agency (in the workplace) have set levels below which exposures are deemed to not be harmful even in sensitive populations. In most cases, nanomaterials are regulated by chemical make up, not size. For example, buckyballs, which are made entirely of carbon, are regulated as carbon black although their behavior may be quite different.

    The city of Berkeley, Calif., recently gained notoriety for regulating nanotechnology by enacting an ordinance that charges nanotechnology users to disclose nanomaterial use and disposal as well as toxicological data. However, as of the June 1 reporting date, Bayer Laboratories was the only company to comply. Cambridge, Mass., is working to develop a set of regulations as well.

    The controversy over whether regulation encourages or discourages industry development is expected to continue.

    No clear consensus exists on certain issues inherent in regulation setting, such as nomenclature or measurement methods. As such, we are not likely to see nanotechnology regulation on a broad scale any time soon. Rather, at this point, the public must rely on the industries that develop, manufacture, use and distribute nanomaterials to produce the safest nanomaterials possible and minimize inadvertent exposures to individuals and the environment.

    Because the size, shape, functional groups and chemical composition of some nanoparticles can be precisely controlled, nanotechnology companies have the unique potential to create materials with decreased bioreactivity or that degrade into nontoxic end products. For example, if a person ingested a nanoparticle that had been modified to prevent uptake by the gastrointestinal tract, his effective exposure would have been zero. It is also possible to sequester a nanomaterial in another material so that as long as this sequestering material is intact, exposure to the nanomaterial cannot occur. However, the lifespan of this material will be an important consideration since, if the sequestering material degrades, later exposures could be considerable.

    As with most substances, individual risk is the product of toxicity and exposure. Reducing exposure to a chemical, including nanomaterials, will decrease any adverse risk. Conversely, if the toxicity of a nanomaterial is low, risk will be low despite high exposures.

    While the possibility of adverse effects on human and/or ecological health is an important concern, these concerns must be balanced against nanotechnology’s tremendous potential. Although it is prudent to use precaution with some nanomaterials, it is vital that growth of the industry as a whole is not stifled. Environmental health and safety risks are present, but they are manageable and can be minimized at every point in the lifecycle of a nanomaterial, from conception to end-of-use.

    Lisa M. Corey, an Intertox staff toxicologist, focuses on toxicology with additional expertise in risk assessment and epidemiology. She holds a master’s degree and is a Ph.D candidate in toxicology at the University of Washington’s Department of Environmental and Occupational Health Sciences.

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