In addition, WADA  may include in the monitoring pro gram substances that are on the Prohibited List , but which are to be monitored under certain circumstances - e.g., Out-of-Competition Use  of some substances prohibited  In-Competition  only or the combined Use of multiple substances at low doses (“stacking”)  - in order to establish prevalence of Use or to be able to implement adequate decisions in regards to their analysis by laboratories or their status within the Prohibited List .