Nanotoxicity

Fullerenes exhibit little pulmonary toxicity in vivo, according to a new study in rats (Nano Lett., DOI: 10.1021/nl0710710). The finding is contrary to those of earlier in vitro tests that showed that C₆₀ is toxic to human cells, including dermal fibroblasts, lung epithelial cells, and astrocytes.

Christie M. Sayes, David B. Warheit, and colleagues at the DuPont Haskell Laboratory for Health & Environmental Sciences, in Newark, Del., took aqueous solutions of nano—C₆₀-a water-soluble aggregate of pristine, underivatized C₆₀—and instilled them into the trachea of rats. They then examined the animals' lungs after one day, one week, one month, and three months. A similar experiment was carried out with the compound C₆₀(OH)₂₄, a fullerene derivative that has been shown to be benign in in vitro tests.

In both cases, the DuPont team found only transitory inflammatory and cell injury effects, probably due to the instillation procedure. Even with the highest dose of fullerenes, no adverse pulmonary effects were observed after three months of exposure, the researchers report.

"The results demonstrate that understanding how nanomaterials interact with the body is more complex than can currently be determined from in vitro studies alone and support the need for systematic research into underlying mechanisms of interaction," comments Andrew Maynard, chief scientific adviser for the Project on Emerging Nanotechnologies at the Woodrow Wilson International Center for Scholars, in Washington, D.C.