Adverse effects of marijuana: selected issues.

I have selected two areas of concern about cannabis that have emerged because new patterns of usage are perceptible over the past few years. In the case of pulmonary pathology there is good reason to suspect that long term use can result in inflammatory or neoplastic changes, particularly when the lung has a double burden of dealing with both tobacco and cannabis smoke. With reference to chronic substantial cannabis use and its impact on brain function, the definitive studies are yet to be done. If clinical impressions are meaningful, some people, especially young people, can sustain temporary and perhaps permanent impairment of nonintoxicated mental performance.