H. Wang/Environmental Protection Agency Photo
Radish plants at various level of exposure to bulk and nano-sized copper oxide. On the far left is an unexposed plant; on the far right is a plant exposed to nanoparticles at the level of 1,000 parts per million.
(NHI Nanoblog) Researchers from the National Institute of Standards and Technology and the University of Massachusetts, Amherst, have found that super-small copper oxide particles can pile up in plants—and stunt their growth, adding to the questions over whether nanomaterials pose a risk to the food chain.
The scientists from UMass and NIST, a branch of the U. S. Department of Commerce, used radish plants (to test a crop people eat) and two kinds of ryegrass, which are typically eaten by grazing animals. They dosed them with bulk and nano-sized copper oxide particles, to explore whether the oxidation effect of the substance — already known to cause DNA damage — was more pronounced at the ultra-small scale.
They found that the radish plants were more sensitive than the grasses, with greater DNA damage and accumulation within the plant at the nanoscale level (the larger particles had far less of an effect). However, all three plant types suffered in terms of growth, when exposed to the nanoaparticles.
The authors of the paper, who include NIST chemist Bryant C. Nelson, are careful to point out that the levels of copper oxide particles are higher than would typically be found in normal soil. Still, the study highlights the uncertainty surrounding the potential effects of nano-enabled products on the food chain and the ecosystem.
Nanotechnology leverages the often-unique properties of super-small particles (a nanometer is a billionth of a meter) to create products with amazing qualities. These materials can make better batteries or lighter and stronger bike frames, as well as new medical instruments and medicines that can save lives. They’re increasingly common in consumer products, from “mineral-based” sunscreens to stain-repellent pants to boat paints that resist algae growth.
Nanomaterials are believed to hold great promise for a wide variety of applications. Their ultra-tiny size also gives them different properties; scientists are struggling to figure out whether that can make them dangerous in the process, and how and why it happens.
Swedish researchers recently found that polystyrene nanoparticles were absorbed by algae, then zooplankton, and then fish, suggesting that the substances can travel up the food chain. This kind of work has potentially broad implications for a variety of nanomaterials, especially those — such as nanosilver and nano-sized titanium dioxide and zinc oxide — that are regularly used in consumer products that are likely to be washed off or flushed away.
NIST is doing this kind of work to help understand the characteristics of many nanomaterials, in order to evaluate them for potential health and safety problems.