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NC State Professor Discusses Nanoparticle Toxicity

By Thaddeus Schug
November 2009

James Bonner, Ph.D.
Bonner has several collaborators at NIEHS, including Langenbach, Clinical Research Unit Staff Clinician Stavros Garantziotis, M.D., Staff Scientist/NTP Pathologist Mark Cesta, D.V.M., Acting Clinical Director Darryl Zeldin, M.D., and former Postdoctoral Fellow Jeffrey Card, Ph.D., who is now a scientific and regulatory consultant with Cantox Health Sciences International.
(Photo courtesy of Steve McCaw)

NIEHS grantee James Bonner, Ph.D., an associate professor in the Department of Environmental and Molecular Toxicology at North Carolina State University, gave a seminar at NIEHS on October 15 outlining some of his latest findings on engineered nanoparticles. Hosted by Robert Langenbach, Ph.D., a principal investigator in the NIEHS Laboratory of Molecular Carcinogenesis, Bonner's talk addressed "Environmental Exposure to Engineered Nanomaterials as a Potential Cause of Lung Inflammation, Fibrosis, and Cancer."

As Bonner ( NIEHS told his audience, despite the growing use of nanoparticles in manufacturing, "we have no idea how some of these structures interact in biological systems - nor do we understand the potential toxicological risks they impose on our environment." A former postdoc and group leader at NIEHS, Bonner is currently heading an effort to determine whether nanoparticle exposure presents risks similar to those associated with asbestos inhalation. "Although epidemiological data are lacking in nanotechnology toxicology and people are not sick yet," he said, "we are in a position to fix a problem before it exists." His group's latest study ( NIEHS appeared online October 25 in the journal Nature Nanotechnology.

Bonner explained that nanoparticles are engineered materials whose sizes fall into the 1-100 nanometer range - the smallest of which are similar in diameter to a DNA molecule. His group focuses on carbon nanotubes, which consist of a thin cylindrical string of carbon atoms engineered either as a single-walled tube or as multiple concentric tubes. He pointed to the tremendous potential for commercial applications of nanoparticles, ranging from the design of lightweight spacecraft to medical uses as filters for kidney dialysis, scaffolding for skin graphs and as shuttles for drug-delivery systems.

In an effort to better understand the health and safety risks associated with emerging nanoparticle technology, Bonner has teamed with a group of nanoscience experts to form an NIEHS-funded Grand Opportunity (GO) program, directed by Health Science Administrator Srikanth Nadadur, Ph.D. The aim of this consortium is to standardize the practices used in measuring and evaluating potential nanoparticle toxicity. Bonner cautioned that public perception of nanoparticle toxicity may not be consistent with published reports, and it is important for investigators to unify research procedures in nanotechnology in order to prevent misconceptions and avoid misinformed policy decisions.

In his lecture, Bonner reviewed some of his groundbreaking work in fiber toxicity, in which he discovered similarities between the reactions of lung cells to nanotubes and asbestos fibers. Bonner noted that when mice were exposed to a spray of single-walled carbon nanotubes, the nanotubes formed unique structures that bridged macrophages, the phagocytic cells in the lung. He compared these nanostructures to tangled fishing lines within the cell's cytoskeletion and emphasized that it could be difficult to predict how different engineered nanomaterials might interact with biological systems at the molecular level.

Bonner concluded the seminar by describing his most recent published work, ( a collaboration involving investigators with NC State University, The Hamner Institutes for Health Sciences and NIEHS. This research shows that multiwalled carbon nanotubes inhaled by mice reach the outer lining of the lungs and cause unique pathological changes. The results suggest that minimizing the inhalation of nanotubes during handling of the material in occupational settings is advised until further long-term studies can assess whether carbon nanotubes cause pathological effects similar to those seen with asbestos fibers.

(Thaddeus Schug, Ph.D., is a postdoctoral fellow in the Laboratory of Signal Transduction at NIEHS, where he studies age-associated diseases in mammals.)

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