The first stage of drug involvement is having the opportunity to use (regardless of whether the individual uses the drug or not), which forms the “exposure opportunity” in the epidemiology of drug use (Wagner and Anthony, 2002). Opportunity is required for use to occur, and forms an individual’s earliest necessary condition from which they are at risk of developing cannabis dependence. Recent research indicates the majority of adolescents who have an opportunity to use cannabis progress to initiation of use (Caris et al., 2009; Lopez-Quintero and Neumark, 2015; Pinchevsky et al., 2011), making the opportunity to use an important target for intervention (Neumark et al., 2012).
