In terms of the physical damage that can be detected only after a number of years, we might think of damage affecting reproductive functions.
Take, for example, a person who might have been the victim of an accident at a very young age. It could be that they would be only aware of a problem with their reproductive system 30 or 40 years later when they tried to have children. Some damage does not reveal itself immediately because life situations mean that one does not recognize it immediately.
In my view, including a 50-year period would cover the totality of physical damage that might take some time before it becomes known or recognized.