Carbon nanotubes.
As cutting-edge nanomaterials move into the construction industry — promising fireproof windows and super-strong building walls — researchers must make a huge effort to understand how they could affect people and the environment, both now and long into the future, a new study recommends.
The report, published last month in the scientific journal ACS Nano, reviews existing research on nanomaterials and concludes that while there are exciting possibilities for the construction industry, there could be danger ahead, too.
Pedro J. Alvarez, an engineering professor at Rice University and one of the study’s three authors, said that there’s no question that nanotechnology — which makes products from particles as tiny as a billionth of a meter, with enhanced strength or superconductivity — has the potential to be revolutionary. But, he added, there are always tradeoffs.
“Frankly, our history is full of initially promising technologies that have created a lot of collateral damage,” Alvarez said.
He cited DDT, a highly effective insecticide that helped curb malaria but also decimated bird populations, as one example. Another is asbestos, which was widely used for several decades as a fireproofing material — until scientists realized it also could cause major lung diseases.
Alvarez’s study, written with Rice researcher Jaesang Lee and Shaily Mahendra, a UCLA professor, warns that some of the properties that make nanomaterials valuable could also have a profound environmental impact.
“I have come to the conclusion that the benefits will outweigh the risks, but that does not mean that we should just take a laissez-faire attitude,” Alvarez said.
Nanoparticles, he said, are so new that it’s difficult to pinpoint exactly how, why and when they might morph into something dangerous. Because buildings are designed to stand for decades, Alvarez said, it’s crucial for researchers to understand what might happen to the nanomaterials over years of use and weathering, and especially during demolition.
Some of the existing manufactured nanomaterials that show promise for the construction industry are carbon nanotubes, which help make steel stronger and more heat resistant, Alvarez said. Other nanoparticles are or could be used as coatings that can make windows fireproof or help exterior walls repel dirt, he said.
The big question is what effect these materials might have. The study cites research on how various manufactured nanomaterials affect animals and people. One study, for example, found that exposure to carbon nanotubes damaged the mitochondrial DNA of laboratory animals. Other research cited in the study found that quantum dots, a type of semiconductor which contain heavy metals such as cadmium and lead, could cause the accumulation of these metals in the kidneys.
Scientists are racing to keep up with innovation in exploring the ramifications of these nanomaterials, Alvarez said. “One of the questions that we’re trying to answer is how we engineer them to be safer without sacrificing the property that makes them useful.”
The study concludes that the construction industry should adopt stringent controls for using manufactured nanomaterials. They include using the smallest amount possible and anticipating how the materials could be recycled at the end of a building’s life.
Paul Schulte, director of the Education and Information Division at the National Institute for Occupational Safety and Health, said the issues raised in Alvarez’s study aren’t new. Schulte, who recently co-authored a study looking at how to develop limits on exposure levels for nanotechnology workers, said many researchers are studying the potential risks of these particles.
Schulte said it’s encouraging that there are efforts to understand the risks of nanoparticles. With substances such as asbestos, he said, evidence of health problems were buried or ignored for years. That’s not happening in what’s still a very young nanotechnology industry, he said.
“Clearly, when you look just generally, there is manifold more research going on in applications of nanotechnology than the implications,” Schulte said. “My take is that what we’ve found so far substantiates some of our concerns, but at the same time it appears to be assuring that we have means of controlling it, at least when we’re talking about workers.”
NIOSH is studying multiple ways to determine and measure the risks to workers of a wide variety of nanoparticles, Schulte said, as part of a larger effort to develop a way to minimize and manage those risks.
For the construction industry, which already manages myriad other dangers to its workers, some existing precautions may also handle dangers from nanoparticles, he said. For example, he said, some protective gear that’s already in use also prevents workers from inhaling the tiny particles.
Alvarez said the international effort to promote safety alongside cutting-edge science is important — as are market forces, which will push nanotechnology companies to take potential dangers seriously.
“I think that the correct way to go is somewhere in the middle, where we allow for innovation but we pace it with a time that allows for data analysis and feedback,” Alvarez said.
