There is a general lack of information on the fate and effects of
engineered nanoparticles (NPs) in aquatic systems. Our study presents the
first data on the toxic potential of silver NPs in a green alga and
emphasizes the need to characterize the fate of particles in experimental
media in order to correctly interpret ecotoxicity data.
Emerging studies indicate that particle properties are expected to change
depending on the chemical characteristics of their receiving environmental
media. For instance, changes in size and charge do occur depending on the
acidity, ionic strength, or water hardness of the medium.
"Our studies address questions on the influence of
physicochemical changes occurring to NPs in freshwaters on
their bioavailability and hazards to algae."
"Increasing use of nanomaterials- based consumer products
by society, proportionally increases the release of
nanoparticles into the environment."
Since the same changes can be projected to also influence particle uptake
and effects in aquatic organisms, they require particular consideration in
studies on particle toxicity.
Does it describe a new discovery, methodology, or
synthesis of knowledge?
Silver NPs could be toxic because of their size, shape, and surface charge.
On the other hand, silver NPs could be toxic because they release silver
ions, which are known to be highly toxic to aquatic organisms, including
The study describes an experimental approach that allows distinguishing
between the contribution of NPs as such and silver ion exposure to
toxicity, using cysteine as a ligand to bind dissolved silver ions.
Our research presents evidence for the negative effects of silver NPs on
algal photosynthesis and demonstrates that the short-term toxicity of
silver NPs is caused by the formation of silver ions from particles upon
contact with algae.
Would you summarize the significance of your paper
in layman's terms?
The study indicates that silver NPs are toxic to algae. Together with other
findings demonstrating the release of silver NPs into the environment, our
findings indicate that associated ecotoxicological risks should not be
underestimated. Thus, in case of silver, a priority goal should be to
prevent silver NPs spreading in the environment.
How did you become involved in this research, and
were there any problems along the way?
We have become involved in this research following the internationally
claimed needs to assess risks associated with the release of nanomaterials
into the environment. In the case of metal-based particles that may
dissolve upon oxidation and lead to the formation of toxic metal ions, this
line of research could build on our expertise in the biogeochemistry and
ecotoxicity of metals.
Where do you see your research leading in the
Our studies address questions on the influence of physicochemical changes
occurring to NPs in freshwaters on their bioavailability and hazards to
algae. The main objective is reaching a fundamental understanding of the
processes governing NPs' changes and toxicity, because, depending on their
surface modifications, NPs might enter cells through different pathways.
Such information will be important also for understanding how NPs will be
transferred along the food chain.
Do you foresee any social or political
implications for your research?
Increasing use of nanomaterials-based consumer products by society
proportionally increases the release of NPs into the environment.
Mitigation of concerns and communication of potential environmental risks
depends on the availability of high-quality data on the fate and hazards of
NPs. Such type of information will provide a strong scientific foundation
for the development of future legislations and is expected to influence the
societal risk perception for nanomaterials-based consumer products.
Dr. Renata Behra
Swiss Federal Institute of Aquatic Science and Technology
Dübendorf, Switzerland Web