It did not evaluate in any detail the release mechanisms. The main conclusions from that work are as follows (Nowack et al., 2012): The release of CNTs from products or articles containing CNT-composites may occur over a long time scale and thus this material will probably alter at a slow rate. It was considered that CNTs can be released upon photochemical Crenolanib degradation of CNT-containing composites. These released CNTs can be transported

to wastewater treatment plants (WWTP) or be directly deposited into environmental compartments where they would undergo transformation by photochemistry, oxidation, adsorption of natural organic matter and other organic Panobinostat supplier colloids, biotransformation, and continued abrasive forces. These transformation processes are thought to change CNT aggregation, dispersibility, and interaction with biota in the environmental compartment. The disposal methods, i.e., incineration, WWTPs, and landfill disposal apply to both the CNT composite as well as released CNTs. The incineration of CNT composites subjects them to high temperatures that might result in the airborne release of CNTs if the CNTs survive at

low temperature for a short time. Theoretically CNTs should be burned and mineralized during incineration, as the temperature (around 1000 °C) is higher than the ignition temperature of CNTs (normally below 600 °C) (Sobek and Bucheli, 2009) and the waste is incinerated in the presence of oxygen. However, poorly controlled incineration might result in lower temperatures that would not destroy the CNTs. Disposal of CNT composites in landfills could lead to degradation

or transformation of the polymers, resulting in possible release of CNTs, depending on the presence and efficiency of landfill liners. The main conclusion from this generic release scenario is that after release of CNTs to the environment a multitude of reactions can affect the form of the CNTs and result either in complete destruction or change of properties. The potential release scenarios that are formulated in this review begin with formation of the solid product (master batch) and move Y-27632 2HCl through its life-cycle as a product and article, ending with the article’s reuse or disposal. Exposure scenarios during formation of the master batch as presented by (Fleury et al., in press) are therefore not part of our analysis. The synthesis of CNTs and the making of the master batch (extrusion) are not included in the evaluation. The pelletizing of the master batch is the first process considered. The life-cycle may roughly be broken into three stages: – Manufacturing of CNT/matrix, i.e. the introduction of CNTs into the matrix, and the ultimate product, e.g. a master batch or paint, or article made from/with the CNT/matrix.