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　　Nanoparticles（纳米粒子） are everywhere，from cosmetics and clothes，to soda and snacks.But as common as they are，they also have a downside，say researchers at Binghamton University and Cornell University in a recent paper published in the journal Nature Nanotechnology.These tiny particles，even in low doses，could have a big impact on our long­term health.

　　According to the lead author of the article，Gretchen Mahler，assistant professor of bioengineering at Binghamton University，much of the existing research on the safety of nanoparticles has been directly related to health effects.But what Mahler and a team of researchers really wanted to know was what happens when someone gets constant exposure in small doses—the kind you'd get if you took a drug or supplement that included nanoparticles in some form.

　　“We thought that the best way to measure the more subtle（精细的） effects of this kind of intake was to monitor the reaction of intestinal（肠道的） cells，”said Mahler.“And we did this in two ways：through human intestinal­lining cells that we had cultured in the lab，and through the intestinal linings of live chickens.Both sets of results pointed to the same thing—that exposure to nanoparticles influences the absorption of nutrients into the bloodstream.”

　　The uptake of iron was of particular interest due to the way it is absorbed and processed through the intestines.“What we found was that for brief exposures，iron absorption dropped by about 50 percent，”said Mahler.“But when we extended that period of time，absorption actually increased by about 200 percent.It was very clear—nanoparticles definitely affect iron uptake and transport.”

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