Environmental Factor, May 2009, National Institute of Environmental Health Sciences
NIEHS Speakers Offer Caveats During NIH NanoWeek
By Eddy Ball
The NIH Nanotechnology Task Force and the NIH Nanomedicine Roadmap hosted a series of symposia and other events in Natcher Auditorium on the NIH campus April 7- 10, celebrating "The Promise of Nanotechnology for Medicine." While the general tone of NanoWeek (http://www.niehs.nih.gov/news/media/questions/sya-nano.cfm) was upbeat and optimistic, talks by NIEHS Senior Science Advisor Sally Tinkle, Ph.D., and grantee Martin Philbert, Ph.D., on April 7 struck more cautious notes, as they addressed concerns about the impact of this promising technology on public health and the environment.
Tinkle serves as a lead representative of NIEHS on trans-NIH, interagency and international nanotechnology and Nano-Health working groups. Philbert (https://www.sph.umich.edu/iscr/faculty/profile.cfm?uniqname=philbert) is a professor of Environmental Health Sciences and the senior associate dean at the University of Michigan School of Public Health. He is a former member of the NIEHS National Advisory Environmental Health Sciences Council (NAEHSC) (http://www.niehs.nih.gov/about/boards/naehsc/index.cfm) and a toxicological pathologist whose nanomaterial research is supported in part by NIEHS.
Tinkle spoke briefly on "Harnessing the Power of Nanotechnology for Human Health at the NIH." She established common ground with her audience, which had spent the day hearing enthusiastic reports on the many advancements in imaging and targeted drug delivery of medications possible through nanotechnology, by underscoring the "shared research questions" and "same research goals" at the intersection of basic and clinical research and exposure prevention research.
Tinkle encouraged scientists to keep in mind the ambiguity inherent in the term "harnessing." While most of the day's speakers had talked of harnessing in the sense of "mastering" nanotechnology for innovative applications, Tinkle said that the word also can signify "holding back" - progressing more cautiously in a responsible manner with a new technology whose nanobiointeractions remain inadequately understood.
Philbert's talk developed the themes of Tinkle's message with an impressive catalogue of reasons to be concerned about the long-term effects of exposure to nanomaterials, supported by extensive data from his recent research. Toxicological testing conducted thus far has led him to conclude that nanomaterials have "[patterns of] pharmacokinetics that are much more complex than in a single molecule" and a marked susceptibility to contamination and "nuisance-surface chemistry" during manufacture and use.
The talk began with an overview of the various methods employed in the synthesis and manufacture of nanomaterials - producing a heterogeneous range of particles with a high surface-to-volume ratio whose impacts on health and the environment can be highly unpredictable. He noted that some cells will accumulate and aggregate nanomaterials in ways that could lead to unexpected super concentration and that carbon nanotubes, under the right conditions, can stiffen and behave like asbestos.
Accurately assessing of risk is also fraught with problems, he said, including coming up with a well-characterized material for testing and determining just what part of the material might have caused the effects observed in experiments. "One [also] has to be very careful in transition from in vitro to in vivo models," Philbert argued. "We need to be more vigilant in following these cases out in time" - noting that it can take two to three decades to develop frank symptoms of disease triggered by asbestos exposure.
In closing, Philbert urged the scientists to broaden their perspectives to consider the entire lifecycle of nanomaterials from manufacture to disposal. "As we move into this era of what Mauro [Ferrari, a previous speaker] called ‘second- and third-generation nanomedicine,'" he argued, "we need to be very mindful of the manufacturing processes."
There should be more attention paid to using "green" manufacturing and producing more biodegradable materials that won't persist in the environment. However great the immediate potential of nanotechnology for improving diagnosis and treatment, Philbert insisted, scientists and regulators also need to see this wonder technology framed by the possible long-range unintended impacts on human health and the ecosystem.