Unseen and unforeseen: measuring nanomaterials in the environment
International interest and investment in nanotechnology is growing—said panelists in this morning’s public forum in Washington, D.C. hosted by RTI International—and development and commercialization of this technology need to meet societal expectations. That is, explained moderator Jim Trainham of RTI, the public is concerned with understanding and controlling nanotechnology since, if it cannot be controlled, the technology is not considered helpful to society.
Perhaps surprisingly, nanoparticles are not just synthetic, engineered nanotubes—nanoparticles occur naturally as salt from ocean spray or as ash from a volcanic eruption. “We are exposed to nanomaterials constantly,” said Cole Matson from Duke University’s Center for the Environmental Implications of Nanotechnology, “every breath we take.” It is this abundance of tiny materials that makes measuring the engineered nanoparticles more difficult. As Michele Ostraat from RTI’s Center for Aerosol and Nanomaterials Engineering explained, it is almost impossible for researchers to distinguish between background—that is the common, everyday nanoparticles—and engineered particles. Even more complicated, she said, there is a general lack of instrumentation that can perform real-time field measurements.
Therefore, the concern with regulating nanotechnology is finding a way to measure how the engineered particles interact with the environment, including how the environment alters these particles once released. It is a matter of measuring the risk to human and ecosystem health by determining the exposure to and hazard of the materials, Matson explained. “Everything has an impact,” said Matson, “the question is, is it detrimental?”
So far there are general answers to these broad environmental questions. According to Matson, nanoparticles will reach the environment, they will be taken up by organisms, they may be toxic, they can alter ecosystems—including “managed” ecosystems such as wastewater treatment facilities—and they do interact with other contaminants.
For all that is still unknown, there are some existing tools that are known being used to track the effects of nanomaterials, said Sally Tinkle from the U.S. National Science and Technology Council. For example, she said, “we have a long history of tracking particulate matter.” Matson and Ostraat agreed that aerosol research is the most prepared for tracking the distribution of nanoparticles. “We are farther ahead with air than water and particularly soils,” said Matson.
One of the primary challenges is that, like any material, nanoparticles change when introduced to an environment. The physical and chemical properties shift, said Tinkle, “gold becomes red, carbon becomes electric.” As Matson outlined as an example, salt alters particles in a marine ecosystem. Therefore, how nanoparticles are affected by salinity in the ocean determines where the particles will be distributed in the water column. Understanding this dispersal could help determine which marine organisms would likely be the most impacted by exposure to nanomaterials.
Jim Alwood from the U.S. Environmental Protection Agency emphasized that more data are needed to improve nanotechnology regulations. But measuring nanomaterials in the environment is difficult, said Ostraat, since nanoparticles do not have a mass, and large particles will create a weight bias in filters designed for measuring these tiny materials. In other words, weighing nanoparticles would not have accurate results. In addition, nanoparticles have a unique dispersal: A nanoparticle “falls one micron due to gravity,” said Ostraat, “but will diffuse 200 microns.” Therefore, as Matson concluded, “designing regulations based on size will not be effective.”
Nanotechnology will have impacts in “ways we cannot presently imagine,” said Jim Trainham. The challenge for scientists, then, is predicting these effects before they become a hazard to the environment and public health. Nanotechnology is undeniably a growing field—according to Tinkle, a$3 trillion business by 2020, a projection based on current products in the nanotechnology field. The panelists all agreed that many countries are seeing the potential for advances in medicine, electronics and alternative energy that are made possible through nanotechnology. However, this rapid growth brings unpredictable challenges.
Photo Credit: Clearly Ambiguous