Cannabis smoke has more tar than tobacco causing increased risk of respiratory illness, lung infections and obstructed airways.
Cannabis smoke causes cancer of the tongue, neck, lung and upper respiratory tract because it contains 50 to 70 per cent more cancer causing ingredients.
The THC in cannabis impairs the immune systems ability to fight off infectious disease and cancer.
Cannabis can affect fertility by reducing the sperm count in men and inhibiting ovulation in women.
Cannabis use affects embryo implantation and may cause miscarriage.
Cannabis use causes damage to short term memory, concentration and the ability to learn because the THC alters the way in which information is processed by the part of the brain responsible for memory formation.
Cannabis use causes a moderate decrease in IQ and verbal abilities.
Cannabis use is associated with impaired educational outcomes, delinquency and crime.
Sleep patterns are disrupted by cannabis use.
Cannabis is addictive and over time greater amounts are required to achieve the same effect.
(Source: Australian Drug Foundation web site)
The cannabis harms are well known and scientifically documented.
Australia can successfully reduced cannabis use and therefore the health risks by copying illicit drug policies from overseas where detoxification and rehabilitation are provided to get users drug free.