It isn't possible to assess and control every risk in the workplace. Some are known as acceptable risks, where the cost of protecting against them would be more than the cost of them happening. There are also what are known as one-in-a-million risks, where the consequences may be serious but the likelihood of them happening is minuscule.
Once again, concentrate on those risks that are both probable and major and work your way down the list until you reach those that are relatively trivial, or serious. Bear in mind that accurate risk assessment can be subjective, and opposing opinions should be listened to when making a decision as to whether a risk needs to be acted upon.