Tiny nanoparticles could be a big problem
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What happens when nanoparticles get out into the environment in wastewater or when products are thrown out?
Nanosilver is the most common nanomaterial on the market. Its extraordinary antimicrobial properties have earned it a place in a huge variety of products, including baby pacifiers, toothpaste, condoms, clothes, and cutting boards.
Virginia Walker, a biology professor at Queen’s University in Kingston, Ontario, decided to study nanosilver one day after a grad student said her mother had bought a new washing machine that doused clothes with silver nanoparticles to clean them better.
It sounded intriguing, Walker recalled thinking, but what would happen if nanosilver in the laundry water wound up in the environment? “What would it do to the bacterial communities out there?” she wondered.
On a whim, Walker decided to study the question. She figured the nanosilver would probably have no impact on beneficial microbes in the environment because any toxicity would be diluted.
“I did the experiment almost as a lark, not expecting to find anything,” she said by phone. “I hoped I would not find anything.”
In fact, Walker found that nanosilver was “highly toxic” to soil bacteria. It was especially toxic to one kind of nitrogen-fixing bacterium that is important to plant growth.
“If you had anything that was sensitive to nanoparticles, the last thing you would want is to have this microbe affected,” Walker said in a phone interview from her office.
The study prompted Walker to do more studies on nanoparticles. In one study now being reviewed for publication, one of her students found that mice exposed to nanoparticles developed skeletal abnormalities.
“People should have their eyes open. There are so many different nanoparticles, and the consequences of their use could be grave. We know almost nothing about these things,” Walker said.
Other scientists have raised concerns about nanosilver too. Some clothes makers now put it in socks and shirts, promising it will help control body odour. In a 2008 study in the Washington, D.C.–based journal Environmental Science and Technology, researchers took nanosilver-laced socks and washed them in water. They found the socks released up to half of their nanosilver into the water.
“If you start releasing ionic silver, it is detrimental to all aquatic biota. Once the silver ions get into the gills of fish, it’s a pretty efficient killer,” said study coauthor Troy Benn, a graduate student at Arizona State University, in a ScienceDaily.com story in 2008.
“I’ve spoken with a lot of people who don’t necessarily know what nanotechnology is, but they are out there buying products with nanoparticles in them.”
And what about the promise that nanotech could produce cleaner energy? The idea was that nanoparticles could make solar panels more efficient, be used as fuel additives to improve gas mileage, and make lighter cars and planes.
Most of the promised efficiency gains haven’t materialized, according to a 2010 report from Friends of the Earth. And it turns out that making nanomaterial is itself a huge energy guzzler.
A kilogram of carbon nanotubes—a nanoparticle used in cancer treatment and to strengthen sports equipment—requires an estimated 167 barrels of oil to produce, the Friends of the Earth report said.
Carbon nanotubes are “one of the most energy intensive materials known to humankind”, said a 2010 report to a symposium of the U.S.–based Institute of Electrical and Electronics Engineers.
That report said many nanoproducts may remain profitable despite their high energy cost only because of enormous government subsidies to the nanotech industry—$1.6 billion from the U.S. government last year.
But despite all this, regulation of nanotech remains glacially slow. The European Parliament voted nearly unanimously to recommend that nanoproducts be banned from food in 2009. But the European Commission rejected that recommendation last year, agreeing only that it may require labels on food containing nanomaterials. It will also require labels on cosmetics containing some nanoingredients starting in 2014.
Canada and the U.S. have yet to go even that far. At Health Canada, which regulates nanotechnology, a web page dealing with nanoproducts hasn’t been amended in four years and contains outdated information.
Health Canada spokesman Stéphane Shank did not return calls.
They used to say small is beautiful. But that was before small got scary.