Driving and piloting skills . In 1997 the World Health Organisation concluded that there is an increased risk of car accidents among drivers intoxicated with cannabis, and the risk is magnified when cannabis is combined with alcohol. Cannabis also seriously impairs aircraft piloting skills, with performance still impaired 24 hours after use. There is also evidence that similar long-lasting impairments apply to motor cyclists, train drivers, signal operators, air traffic controllers and operators of heavy machinery. Cardiovascular system .
Cannabis produces dose-related tachycardia, vasodilation and reddening of the conjunctivae.
Fainting can also occur. These effects may carry a risk for people with pre-existing cardiac disease. Respiratory system . The tar from a cannabis cigarette contains higher levels of some carcinogens than tobacco smoke. Immune system, hormones and reproduction .