Toy designers face little physical danger if they're working for a toy manufacturing company because most of their work is done on computer screens in comfortable offices. Perhaps improper seating or an awkwardly designed mouse may lead to carpal tunnel syndrome, but outside of that, little danger arises in the toy world.
Independent toy designers or inventors may work to develop prototypes of their toys, which can expose them to the chance of injury in the form of sharp tools, melting plastic, or noxious fumes. The goal, of course, is for none of these dangers to be passed on in the actual toy itself. This is why Box-O-Knives never took off as a plaything.