The evaluation of the safety of engineered nanoparticles is a key element in reaching the full potential of the benefits offered by the novel properties of these materials. The current practice is that the existing test guidelines for chemical risk assessment are used for this purpose, though some technical changes may be needed. However, evidence in the scientific literature is emerging that these conventional methodologies for assessing chemical risks may not be appropriate for assessing risks associated with nanomaterials.
EnvNano challenges the assumptions behind the use of methods developed and optimized for dissolved chemicals by taking a starting point in the fact that particles behave fundamentally different than dissolved chemicals in the test systems used for risk assessment.
In the first period of EnvNano, experimental studies of engineered nanoparticles in ecotoxicity tests with algae and crustaceans have highlighted that understanding and quantification of the dynamic changes occurring to engineered nanoparticles in water before and during testing may hold the key to a proper interpretation of test results obtained.
A major result of the EnvNano project for the first project period is therefore to propose that a combination of a shortened exposure period with an aging step of engineered nanoparticles in medium prior to testing should be implemented to achieve increased control of exposures in ecotoxicity tests.
Results obtained in EnvNano for uptake and excretion of nanoparticles in freshwater crustaceans (Daphnia magna) and zebrafish underline that the principles of assuming chemical equilibrium between test species and the surrounding environment, traditionally used for dissolved chemicals, are not valid for nanoparticles. Examinations of exposed animals with electron microscopy suggest that even though agglomeration of engineered nanoparticles is observed in test medium they may disagglomerate when deposited in the gut of daphids. Furthermore, a series of studies showed different uptake behaviour and different potential for trophic transfer dependent on functionalization of nanoparticles tested in experiments where zebrafish were fed with daphnids exposed to engineered nanoparticles.
The experimental findings in EnvNano are directly connected to the development of new risk evaluation approaches within the project frame. This has so far resulted in two frameworks for alternative risk evaluation of engineered nanoparticles. Both of these are designed to operate under severe lack of data. The first framework is aimed at an operationalization and application of “early warning signs” to screen nanomaterials for harmful properties. It shows how the warning signs of novelty, persistency, bioaccumulation, dispersivity, and irreversible action can used as a first screening for potentially hazardous nanomaterials. The second framework is a conceptual tool for categorization and communication of exposure potentials and hazards of nanomaterials in consumer products.
It is the ambition that the research carried out in EnvNano will contribute to expanding the fundamental knowledge base on the environmental risks related to engineered nanoparticles and to the development of methods appropriate for assessing these. In this way strategies for identifying potentially problematic engineered nanoparticles may be implemented at an early stage in the product development and safer alternatives may be found. In the light of the public concerns related to engineered nanoparticles such knowledge is a pre-requisite to a successful large-scale commercialization of nanotechnology.