Finally, few studies have provided information on physical health indices associated with co-occurring cannabis and tobacco use. Tobacco use is a causative factor in a variety of adverse health outcomes (US Department of Health and Human Services, 2010), although the extent of adverse health outcomes associated with cannabis use is less clear. Some studies have reported that cannabis use is related to mutations in lung cells, respiratory problems (e.g., bronchitis, chronic cough/wheeze), and other health-related problems (Aldington et al., 2007; Aldington et al., 2008; Cho et al., 2005; Hall and Degenhardt, 2009; Hashibe et al., 2005; Moore et al., 2005; Pacifici et al., 2003; Tetrault et al., 2007), although other studies have not uncovered similar findings (Hashibe et al., 2006; Pletcher et al., 2012; Taylor et al., 2002). Inconsistency in the association of cannabis use with poor health may be attributed to methodological factors, including lack of statistical control for tobacco use, failure to include individuals who use cannabis frequently, and failure to include individuals who have used cannabis heavily for extended periods of time. In a recent study that
