< snip > We already know that regular use of cannabis is associated with an increased incidence of mental illnesses, most notably schizophrenia and depression < / snip > Comparing cannabis with tobacco Smoking cannabis, like smoking tobacco, can be a major public health hazard Britain now has 13 million tobacco smokers. This number has been steadily decreasing due to public awareness of the harm caused by tobacco smoking. At the same time the number of cannabis smokers is increasing. Between 1999 and 2001, the number of 14-15 year olds who had tried cannabis rose from 19% to 29%...