Nanomaterials in the environment
Different nanoforms of a chemical may behave differently in the environment, because of the nano-specific properties engineered into the material. In the field of environmental fate and behaviour of nanomaterials, science is rapidly evolving.
One way forward is to use the physico-chemical properties of nanomaterials as a starting point, e.g. the water solubility. These key properties can be used to decide on further measurements or if the environmetal fate of the nanoform will be more or less the same as that already established for the non-nano form of the chemical.
For instance, when a readily soluble substance is released to the environment, irrespective of the nano- or non-nanoform, the environmental properties in solution is what should be assessed. If the nanomaterial turns out to be readily soluble then for inorganic substances, the existing information on its bulk could be used to also assess the nanoform.
The environmental fate of chemicals covers different processes, the main ones being degradation (chemical, physical or biological) and/or transformation in the environment. However, the standard methods used to assess degradation of chemicals are, in general, not adequate for nanomaterials. A further complication for nanomaterials is that the surface treatment or coating may affect the environmental fate and behaviour of the nanomaterial.
In addition to the transformation and degradation processes, possible bioaccumulation of nanoparticles in organisms needs to be assessed. Recent work by the OECD indicated the limitations of the current approaches to testing.
The methods to measure and evaluate the fate of the nanoparticles in the environment are under further development. It is expected that improved techniques will be made available in the coming years.