It has been over 13 years since the initial FDA MIST guidance (2008) came out outlining the importance of evaluating the safety of human metabolites. The FDA stance, resulted in an increase in the number of radiolabelled clinical studies being performed. These studies allowed the determination of rates and routes of elimination (mass balance) for drug related material and the identification of major human metabolites. This poster presented at the recent ISSX conference reports data from approximately 60 carbon-14 radiolabelled clinical mass balance studies performed by Pharmaron since 2014.