Nanoparticles Damage Plant DNA


radish sprouts
"Graphic showing that increasing exposure to cupric oxide bulk particles (BPs) and nanoparticles (NPs) by radish plants also increases the impact on growth with NPs showing the largest impact. From left to right, the exposure concentrations are 0; 100 parts per million (ppm) BPs; 1,000 ppm BPs; 100 ppm NPs; and 1,000 ppm NPs (showing a severely stunted plant)."

Significant damage to a plant’s DNA has been caused by nanoparticles in a study by the National Institute of Standards and Technology at The University of Massachusetts Amherst.

This is the first evidence that nanoparticles can accumulate within a plant and damage its DNA.

20120418-151226.jpgThe research team tested the human-made, ultra-fine particles on a food crop, radish, and two grazing crops, perennial and annual rye grass. The compound used in the study, cupric oxide, has been used for many years as a coloring in glass and ceramics, a polish for optics, and as a catalyst in the making of rayon. Cupric oxide is an oxidizing agent that removes electrons from other compounds — it has been shown to cause DNA damage in some organisms. The purpose of the research was to see if “nano-sizing” the compound made it more or less likely to accumulate within the plant and also whether it caused other effects inherently from the nano-sizing.

The research was done by exposing the plants to both normal-sized cupric oxide and the nano-sized versions, as well as copper ions. They then evaluated the formation and accumulation of DNA base lesions and how much of the copper was being taken up.
In the radishes, twice as many lesions developed in the nano-particle-exposed ones compared to the normal-sized cupric oxide. In addition, the copper uptake was far greater in the nanoparticle size. The research also showed significantly stunted growth, in both the roots and the shoots.

“To our knowledge, this is first evidence that there could be a ‘nano-based effect’ for cupric oxide in the environment where size plays a role in the increased generation and accumulation of numerous mutagenic DNA lesions in plants,” according to lead researcher Bryant Nelson.

The researchers are to follow up this study, with one on the effect of titanium dioxide nanoparticles on rice plants. Titanium dioxide is widely used in sunscreens.

Image Credits: H. Wang, U.S. Environmental Protection Agency, A. Keene U.S. Food and Drug Administration

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