Aug 18 2010
Scientists at Purdue University, United States, have demonstrated that one class of single-walled carbon nanotubes (SWNTs) produces cell-damaging reactive oxygen species (ROS) when dispersed in water and exposed to sunlight.
Previous experiments in the laboratory have shown that carbon-based nanomaterials produce ROS when irradiated with a laser, but it was not known, until now, that nanomaterials can generate these highly reactive compounds under natural conditions. Chad Jafvert, an environmental engineer at Purdue, says "[I]f we're going to produce and dispose of large quantities of SWNTs, we need to know how they're transformed in the environment and whether their products are more or less harmful than the parent materials." ROS can oxidize and damage an organism's DNA, lipids and proteins, so these chemically-altered SWNTs could be toxic to aquatic organisms, according to the researchers. Jafvert adds that the environmental significance of these processes is still unknown, because naturally occurring materials called humic acids also generate ROS in water, and the researchers are not clear on whether the SWNTs themselves or chemicals from the manufacturing process create the reactive species. The findings will, however, help scientists understand the toxicity of SWNTs when they are released into the environment.
Source: http://www.merid.org/