Summary:
Study by a Canadian group found that carbon nanotubes may be toxic to microorganisms. When cultures of a certain key protozoan, a single-cell organism, were exposed to the nanotubes their ability to ingest and digest bacteria was hindered. Protozoa exhibited clumping. If such exposure ever occurred in the wild, there is a possibility that the nanotubes move up the food chain, with impossible to forsee ecological effects. Study illustrates need for research into the health and environmental impact of nanoparticles. (Published: 19/06/08)
Notes:
- Univ. of Waterloo group exposed Tetrahymena thermophila to single-walled carbon nanotubes
- exposed to different concentrations of nanotubes in solution and monitored them for three days using video microscopy
- found that the protozoa unnaturally clumped together initially and then ingested SWNTs and bacteria alike
- additionally, the protozoa's ability to ingest and digest their prey bacteria species was compromised
- control cultures remained healthy while the nanotube-exposed cultures exhibited various negative responses depending on the concentration
- ranging from diminished mobility to death, with the most prevalent effect being cell clumping
- one potential positive effect of Tetrahymena thermophila nanotube uptake
- the protozoa released extra “exudates,” fluids rich in proteins and cellular debris
- help solidify impurities in the wastewater
- could make the protozoa more efficient water-cleaners.
- implication: if such exposure ever occurred in the wild, the nanotubes could move up the food chain
- additionally, because the protozoa's ability to ingest and digest their prey bacteria species was compromised, certain bacteria populations could balloon
- could have untold ecological effects
- pressing need for research into the health and environmental impact of nanoparticles
- Part of the reason for the lack of studies on carbon nanotubes effects on microorganisms is that scientists generally believe that the nanotubes are insoluble in water.
- However, at least one recent study challenges this belief.
- “We hope that our work will stimulate a line of research towards better understanding of the effects of nanomaterials on diverse organisms, especially on single-cell organisms that are ecological important,” says Tang.
