Nanoparticles are starting to be used in more and more applications. As their use increases, so does concern about their short- and long-term effects on health and the environment. Masanori Horie and colleagues, National Institute of Advanced Industrial Science and Technology, Japan, have compared Cr₂O₃ nanoparticles and fine particles in cell culture medium.

The fine Cr₂O₃ particles – currently used in industry as catalysts and pigments – were insoluble in the culture medium and were found to be non-toxic. The nanoparticles were shown to be soluble and released hexavalent chromium (K₂Cr₂O₇), human carcinogen, into the medium. The nanoparticles induced oxidative stress and apoptosis on culture cells, meaning Cr₂O₃ nanoparticles show the potential for severe cytotoxicity.

• Chromium(III) oxide nanoparticles induced remarkable oxidative stress and apoptosis on culture cells
  M. Horie, K. Nishio, S. Endoh, H. Kato, K. Fujita, A. Miyauchi, A. Nakamura, S. Kinugasa, K. Yamamoto, E. Niki, Y. Yoshida, H. Iwahashi,
  Environ. Toxicol. 2011.
  DOI: 10.1002/tox.20695