“…The successes of WBE that have been demonstrated on global scales have given rise to discussions on future outlooks for the technique (Choi et al, 2018;Daughton, 2018;Kasprzyk-Hordern et al, 2014;Thomas and Reid, 2011). Initially, work was entirely focused upon illicit drug usage, including heroin, cocaine and methamphetamines (Boleda et al, 2007;Castiglioni et al, 2006;Kasprzyk-Hordern et al, 2008;Zuccato et al, 2008) but have since expanded to include a diverse range of other endogenous biomarkers, varying from ones linked to lifestyle choices such as alcohol consumption (Boogaerts et al, 2016;Reid et al, 2011;Rodríguez-Álvarez et al, 2014a), tobacco (Castiglioni et al, 2015;Lai et al, 2017;Rodríguez-Álvarez et al, 2014b;Ben J. Tscharke et al, 2016) and psychoactive substances (Kinyua et al, 2015;Mardal and Meyer, 2014;Reid et al, 2014). Others have investigated general health through oxidative stress markers (Ryu et al, 2016(Ryu et al, , 2015.…”