Nanomaterials have a much higher surface-to-mass ratio, and while this makes them good for such purposes as water filtering, it also could cause them to interact with body cells that their tiny size allows them to infiltrate.
Jeppe Blak-Nielsen has his own very specific reason for appreciating windmills: "Whenever the turbines at Middel-grunden are running," the Copenhagen yachtsman says, "I know the wind is perfect for sailing."