An employer must review the risk assessment contemplated in subregulation (1) when-
(a) there is a reason to believe that such an assessment is no longer valid;
(b) control measures are no longer effective;
(c) technological or scientific advances allow for more effective control methods; or
(d) there has been-
(i) a change in work methods;
(ii) a change in the type of work carried out;
(iii) a change in the type of plant and machinery used to control exposure;
(iv) an incident or medical surveillance which revealed inadequate control of the risk.