4. Conclusion

Whether we're talking about the environment or human health, the questions raised by interactions between CNTs and living organisms are very similar. Among them, possible biodistribution in organisms and their possible biodegradation are central to long-term effects. As we have seen, it's not always so simple to establish a relationship between a physico-chemical parameter and its impact on living organisms. If length, for example, plays a major role in the ability of immune cells to phagocytose or displace them, it is difficult to decouple it from the effect of surface chemistry, since the methods used to cut/shorten CNTs inevitably lead to simultaneous modification of their surface chemistry. A major challenge concerns the quantification of CNTs in tissues or environmental matrices after exposure. This challenge can be overcome by the use of radioactivity, but the cost of these experiments...