Colvin: "Safety by Design" in Nanotech

SAN FRANCISCO--Nanoscientists have a unique opportunity to ensure that their breakthrough materials do not join DDT, ozone-eating refrigerants and other "wonderful technologies" whose toxic effects have surpassed their usefulness, said Rice University researcher Vicki Colvin on Friday.

The unique properties that make nanomaterials potentially useful in applications from sunscreen to fuel storage are the same properties that may pose environmental and health risks, Colvin said in a lecture at the AAAS Annual Meeting.

Scientists are only starting to fully understand these properties of nanomaterials--a situation which may actually help to avoid some of their potential risks, according to Colvin.

"We can do something pretty unique, which is from the beginning, engineer our materials as safe materials or begin to understand how that might happen," she said.

The materials in question are built from vanishingly small particles, on the scale of a billionth of a meter, with average sizes about the width of the period at the end of this sentence. But their impressively small size is only one of their unique features, Colvin said, noting that their surface area and even basic chemical properties differ from their bulk material counterparts.

"All of the fantastic and unusual properties of these materials are at the heart of their use in technology," Colvin explained, speaking briefly about the distinctive glow of quantum semiconductor "dots" used to pinpoint cancer cells, and tiny spheres of gold--a normally non-reactive metal--that can be used to purify water.

Although researchers recognize that size matters in more than the usual ways when it comes to nanotechnology, regulation of these materials has been slower to catch up. Colvin talked about a material safety data sheet that her students in the lab use to guide safe handling of the C60, or fullerene, carbon molecule, saying that the sheet lists elemental carbon as "mainly a nuisance dust."

The sheet "reflects the larger picture right now of sort of a conventional regulatory standard, which is that nanomaterials are equal to bulk materials when it comes to biological properties," Colvin said. "At what point does size become a variable that you need to control and manipulate and identify when you think about how to handle these new systems?"

Recent research shows that nanoparticles can be inhaled and probably absorbed through the skin as well, potentially causing immune reactions, according to Colvin. Several experiments with rats suggest that particles smaller than 100 nanometers, if inhaled, can make their way into the brain and central nervous system. In other "natural" experiments such as human hip replacements, the nanoparticle debris created as the replacement joint wears away may absorb proteins in the body and over time lead to an autoimmune reaction, Colvin noted.

"Once they [the nanoparticles] are in contact with the body, they are processed through routes that your might expect many foreign objects to get processed, and the rules on that are something that we're just now examining," Colvin said.

There are some preliminary studies, including some from Colvin's lab, suggesting that nanomaterials such as fullerenes can be chemically altered to make them less toxic. But the research is still in its early stages, and engineers will have to consider the "different stories, and different settings" for nanomaterials to come up with ways to make them safer, she noted.

Colvin is professor of chemistry and of chemical engineering at Rice University and director of its Center for Biological and Environmental Nanotechnology, or CBEN. CBEN was one of the nation's first Nanoscience and Engineering Centers funded by the National Science Foundation. She is also the executive director of Rice's International Council on Nanotechnology (ICON), a nanotechnology sustainability group. In 2002, she was named one of Discover magazine's "Top 20 Scientists to Watch."

In 2003, Colvin testified before a U.S. House of Reprsentatives committee on the future of nanotechnology, urging more research on the toxicological and environmental effects of nanomaterials. That, she said, would help avoid the "wow-to-yuck" trajectory, where keen public interest in new technology plummets with rising concerns about its ethical and environmental implications.

In her talk at the AAAS Annual Meeting, Colvin said that regulation of existing nanomaterials--including clear labeling--is necessary. But she also suggested that more research toward "safety by design" could bring better products to market in the future.

For today's nanoengineers, she said, "integrating and thinking about issues of safety and sustainability as early as possible is really critical."

17 February 2007