Marijuana use: sequelae and implications for health promotion

s of 2003, 40% of Americans aged 12 years and older had smoked marijuana at least once.1 Approximately 30% of Canadian youths from Grades 7-12 have tried cannabis at least once.2 Marijuana is the most widely-used illicit substance in Canada, with 10.6% of the Canadian population reporting use in 2009.3 This is similar to the US annual figure of 9%.4 Global reports indicate that the average age of first marijuana use is decreasing, even as the average delta-9-tetrahydrocannabinol (THC) content of cannabis is on the rise. This may lead to an increase in both addictive potential and adverse effects of marijuana use.5