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| Earth on Aug 23, 2012

Carbon nanotubes can be toxic to aquatic animals, says study

The researchers urge that care be taken to prevent the release of carbon nanotubes into the environment.

Carbon nanotubes are some of the strongest materials on Earth and are used in high-performance tennis rackets, tiny transistors, and have potential uses in everything from medicine to electronics to construction.

However, according to a study in the August 2012 journal Environmental Toxicology and Chemistry, carbon nanotubes can be toxic to aquatic animals.

The researchers urge that care be taken to prevent the release of carbon nanotubes into the environment as the materials enter mass production.

Carbon nanotubes. Black clumpy powder, grains shown, partially smeared on paper. Scale in centimeters. Image credit: University of Missouri

Carbon nanotubes are hexagonally shaped arrangements of carbon atoms that have been rolled into tubes. These tiny straw-like cylinders of pure carbon have useful electrical properties. They have already been used to make tiny transistors and one-dimensional copper wire. They were developed by using nanotechnology, a field that involves building electronic circuits and devices from single atoms and molecules. Nano means one thousand millionth of a unit. A nanometer is therefore one thousand millionth of a meter.

But these microscopically thin cylinders of carbon atoms are not pure carbon. Nickel, chromium and other metals used in the manufacturing process can remain as impurities. Deng and his colleagues found that these metals and the carbon nanotubes themselves can reduce the growth rates or even kill some species of aquatic organisms. The four species used in the experiment were mussels, small flies’ larvae, worms (Lumbriculus variegatus) and small crustaceans.

The study was a collaboration between researchers from the University of Missouri and the U.S. Geological Survey. Hao Li is associate professor of mechanical and aerospace engineering at University of Missouri. He said:

One of the greatest possibilities of contamination of the environment by CNTs comes during the manufacture of composite materials. Good waste management and handling procedures can minimize this risk. Also, to control long-term risks, we need to understand what happens when these composite materials break down.

Bottom line: Carbon nanotubes can be toxic to aquatic animals, according to a study in the August 2012 journal Environmental Toxicology and Chemistry, .

Read more from the University of Missouri