Engineered nanoparticles: a new challenge for ecotoxicologists
2009-04-20 16:15 | GR B30
Dr Renata Behra, Eawag
Engineered nanoparticles (ENP) are increasingly produced and used for different applications and their entrance into aquatic environments is therefore predictable. Following a time of controversial debates concerning potential environmental risks, experimental data on the ecotoxicity of various ENPs are now appearing in the literature although mechanisms leading to observed biological effects still remain to be elucidated. ENPs might display direct effects through interactions with target molecules leading to alterations of membranes and biochemical processes. Indirect effects of ENPs may include physical restraints (clogging effects), solubilization of toxic ENP compounds, or production of reactive oxygen species leading to oxidative stress. Considering that the fate and bioavailability of ENP will depend on their physico-chemical characteristics and their interaction with the receiving chemical environment, the physico-chemical characterization of experimental ENPs is a prerequisite for a proper interpretation of ecotoxicity data. With the objective of gathering scientific information on the ecotoxicity of silver nanoparticles (AgNP) we are examining the interactions between AgNPs and the alga Chlamydomonas reinhardtii. AgNPs belong to the most important materials incorporated in consumer products and are widely used because of their toxicity to bacteria. The results indicate that the toxicity of the experimental AgNPs to the photosynthesis of algae is mediated by ionic Ag+ and that Ag+ is formed upon interaction of the particles with algae. A combination of various microscopic techniques indicates that AgNP are present in algae cells. Considering that particles might also form upon precipitation of internalized ionic silver, further analyses are required before concluding on the uptake of silver nanoparticles in algae.
