Potential hazards of nanotechnology

Self-replicating nanobots
The first concern is that of out-of-control, self-replicating "nanobots" that would eventually consume and take over the planet in a style reminiscent to that of "The Matrix".
Alvin Toffler and Heidi Toffler in their brilliant book "War and Anti-War: Making Sense of Today's Global Chaos" theorised the creation of insect-sized attack robots, nano-sized robots which would drill into enemy territory, and start self-replicating to a huge extent. These time-controlled robots could then be set to detonate with the press of a button, providing the ultimate weapon again…