Science - December 22, 2010

Nanoparticles no problem for life in ditches

Worms, snails and other underwater soil-dwelling creatures are not hindered by carbon particles in the environment. But that does not mean the particles are not toxic.

This is what Wageningen PhD scholar Ilona Velzeboer says, on the basis of ongoing research on the effect of carbon nanotubes on soil life forms in ditches. These kinds of particles are ending up in the environment with increasing frequency, due to the nano industry. What is not yet clear is whether this can do any harm. Up to now, research has been exclusively lab-based, and has only looked at effects on a single species.

But Velzeboer really went out into the field for her research, to a ditch in the farmland around Wageningen. There she put out trays of sediment without soil animals but with nanoparticles in various concentrations. The first results are encouraging. Worms, slugs, larvae and other forms of life thriving in the soils turned out to have no difficulty in colonizing the polluted soil. 'Nanoparticles in these quantities show no apparent effect on the composition of soil animals or the numbers of each species', concluded Velzeboer in an article that is due to come out soon in Environmental Toxicological Chemistry. No effect within a couple of months, that is. The experiment is still going on and it is possible that the picture will change after long-term exposure.

The tests in the ditch provide a provisional indication. According to Velzeboer, the effects of carbon particles are especially linked to the interactions which the particles enter into. 'For example, how do they react with other contaminants such as PCBs or perfluoros? Do these substance bind to nanoparticles and if so, where do you find them? In the water phase or in the sediment, and how are they distributed? To measure effects you need an idea of the behaviour of these particles. That is the more chemical side of my research.'
Velzeboer studied environmental physical sciences at Nijmegen. She came to Wageningen Imares in Ijmuiden through an internship with the public health institute RIVM. She is now doing doctoral research in Professor Koelmans' Aquatic Ecology and Water Quality Management chair group.