Even though nanoparticles are increasingly entering the environment, scientists have a lot to learn about their biological effects. Researchers with the IHEP Multi-disciplinary Research Center have found

CeO2's effection on the lifespan of roundworms

that exposure to cerium dioxide nanoparticles shortens the lifespan of the roundworm Caenorhabditis elegans (Environ. Sci. Technol., DOI: 10.1021/es103309n).

Dr. Zhiyong Zhang and his colleagues exposed larvae of the widely used model organism C. elegans to 8.5-nanometer particles of CeO2, showing that they may actually protect against cardiovascular, neurological, and radiological damage in rats, mice, and human cells in vitro, respectively. However, those studies have high concentrations of the nanoparticles. Zhang wants to see how environmentally relevant concentrations of CeO2 nanoparticles might affect an organism's health.

The researchers raised C. elegans larvae on mats of bacteria doped with CeO2 nanoparticles at concentrations ranging from 1 to 100 nM. They then counted the surviving worms each day. At the lowest concentration of 1 nM, the mean lifespan of the worms was 15 days, at the highest concentration of 100 nM, the worms lived 14 days. Compared to the control worms' lifespan of nearly 18 days, the lifespan of worms exposed to nanoparticles decreased by 12%. The researchers believe the shortened lifespan is related to oxidative stress.

"We never expected to find any negative effects at such a low concentration," Zhang said,” This is only the first study indicating adverse effects of nanoparticles in the 1- to 100-nM range. “He also mentioned that CeO2 nanometer particles can be applied to many high-tech fields, such as catalytic converters, polish for silicon wafers and potentially many other areas.

Source: American Chemical Society website 

http://pubs.acs.org/cen/news/89/i14/8914scene4.html