Could nanotechnology pose threat to crops?

11/21/2012 5:57 AM

11/21/2012 7:07 AM

Fast-developing know-how makes our khakis resist stains, artificial bones more practical and diesel burn more efficiently.

That nanotechnology builds microscopic wonders inhabiting a man-made universe that smothers stink and mops up pollution by working on a scale that makes a dust mite look gargantuan.

Yet research still in its infancy, and trailing the deployment of emerging commercial applications, suggests those same breakthroughs in nanotechnology might some day make Midwestern crops less bountiful.

Scientists in California planted soybeans in soil doused with two kinds of metallic nanoparticles to see if the super-small manufactured stuff would just sit in the dirt like miniature pebbles or become part of the plants.

In ground spiked with zinc oxide nanoparticles, soybeans seemed to fare slightly better than normal. In soil treated with cerium oxide nanoparticles, the plants grew fewer leaves and punier bean pods.

Both examples, researchers wrote, showed the micro-materials became part of the plants.

That raises implications for the fields of Kansas, Missouri and the rest of the Grain Belt where, scientists presume, manufactured nanoparticles have been accumulating for a few decades now.

“The stuff is going to end up somewhere,” said Patricia Holden, a professor of environmental microbiology at the University of California-Santa Barbara and a lead researcher in the soybean study. “We’re only beginning to learn what that might mean.”

Her research, published in the Proceedings of the National Academy of Sciences earlier this year, raises fresh worries about nanotechnology. Some critics say it’s becoming quickly integrated into the modern economy and the world environment faster than scientists can sort out its potential dangers.

“We need to put together a model where we’re thinking this through before we get to a point that we can’t undo it,” said Patty Lovera, an assistant director of the consumer advocacy group Food & Water Watch.

No one is suggesting this winter’s wheat crop or next fall’s corn harvest looks in jeopardy. And some analysts said the research mimics far greater contamination than farmers would find in their fields.

“They dosed the hell out of a bunch of soil,” said Todd Kuiken, a senior researcher at the Woodrow Wilson Center’s Project on Emerging Nanotechnology. “A soybean crop would never get dosed with that much.”

Still, he noted it fills in a small piece of a largely unsolved puzzle: Nanoparticles can be absorbed by the plant, and cut back that plant’s ability to produce food.

That’s still a long way to knowing whether nanotechnology is a threat to crop yields, or whether grains laced with nanoparticles are a danger to livestock or humans.

Kuiken sees problems in what we still don’t know: how much contamination matters to plant growth, and the level of nanoparticles sullying the environment today — or likely to build up as the technology becomes more widely used.

Figuring out how common man-made nanoparticles have become in the environment is partly a question of size. They’re so small, they can be hard to find. And scientists are still lacking the kind of instruments that can detect them.

Nanotechnology works at a seemingly impossibly small scale, marrying chemistry and engineering to manipulate matter at a molecular and atomic scale. At that tiny size, the matter can take on valuable new qualities.

At their largest, nanoparticles measure one-tenth the size of a period on the printed page. The tiniest of nanoparticles are another 500 times smaller.

For years, nanotechnology has proven increasingly valuable. Richard Smalley of Rice University won a Nobel Prize in 1996 for discovering a new supercarbon of just 60 atoms invaluable for making small and precise ingredients for electronics and drugs.

Federal spending on nanotechnology research now nears $2 billion a year.

It’s yielded a range of products and manufacturing processes. Nanotechnology can make vitamins and some drugs more easily absorbed. It can make paints brighter and more long-lasting. It’s used to treat leather, to make metals harder, to make your smartphone screen thinner and lighter.

Nanoparticles have become increasingly commonplace in recent years in sunscreens and cosmetics. Silver-based nanoparticles can even make your socks stink less.

But consider that odor-fighting quality as an example of the potential danger of nanotechnology. Your stockings smell better because the nanoparticles ward off bacteria. So what happens when one wash cycle after the next some of them break free and run through sewer lines to the local waste water treatment plant?

Critics like Lovera of Food & Water Watch say those antibacterial qualities could make it more difficult for the sewage plant, which relies on bacteria to break down sludge, to treat what’s flushed down your toilet. And fertilizer that facility passes on to farmers could store a concentration of nanoparticles — perhaps to be absorbed in their soybean crop.

Putting the brakes on nanotechnology might be neither simple nor desirable. After all, it’s proven a valuable environmental scrubber.

Ken Klabunde, a Kansas State University distinguished professor of chemistry, spun off a company from his nanotechnology research that produces products used to detoxify chemical weapons. It also sells products to snuff out skunk odors or to kill the rotten egg smell associated with some drywall imported from China.

Klabunde recognizes that potential danger exists with any new technology. The key safeguard, he said, is to stick with safe substances. For instance, he says industry should avoid mixing nanotechnology with materials such as lead that are known to pose a threat to people. Zinc, which is among the minerals used by the company he created, and cerium are not toxic.

“There are many things on the periodic table that we could make nano and would be highly toxic,” he said. “There could be unintended consequences if we’re not careful.”

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