Researchers have learned a great deal about how THC acts on the brain to produce its many effects. Upon smoking marijuana, THC rapidly passes from the lungs into the bloodstream, which carries the chemical to the brain and other organs throughout the body. THC acts upon specific sites in the brain, called cannabin receptors, igniting a series of cellular reactions that ultimately lead to the effect that users experience when they smoke marijuana. Some brain areas have many cannabin receptors; others have few or none. The highest density of cannabin receptors is found in the parts of the brain that influence pleasure, memory, thoughts, concentration, sensory and time perception.
Most experts agree that most marijuana smoke contains carcinogens and with chronic use will affect the lungs. In fact, is has been argued that street marijuana smoke contains 40 to 60 percent more carcinogenic hydrocarbons than tobacco smoke. This might be because marijuana users usually inhale more deeply and hold their breath longer than tobacco smokers. Some research suggests that Marijuana smokers show deregulated growth of epithelial cells in their lung tissue, which could lead to cancer. Other studies have found no positive associations between marijuana use and lung, upper respiratory, or upper digestive tract cancers. Thus, the link between marijuana smoking and these cancers remains unsubstantiated.
In response to the increased health risk associated with smoking, there are a growing number of medical marijuana users who are putting down their pipes and paper in favor of ingesting THC through capsule, food, and sublingual strips. A much safer approach says the medical community. Further, there is increasing evidence that sublingual strips and other forms of digestive intake have many of the medicinal benefits of THC but without the added risk of respiratory danger that inhaling any form of smoke presents.
Treatment programs focused solely on addiction to marijuana is extremely rare. Yet much of the health community believes that continued and regular use of marijuana can cause addiction and even physical withdrawal symptoms such as nervousness and insomnia. Other medical researchers and health professionals argue otherwise. The debate rages on as more states consider legalizing or reforming their marijuana laws in favor of regulated medical use. Notwithstanding, there are a reported 150,000 individuals each year who voluntarily enter treatment programs for what they consider addiction to marijuana. In fairness, a majority of those who seek treatment for addiction to marijuana are also seeking treatment for addiction to other types of drugs (legal or otherwise) such as cocaine, amphetamines, barbiturates and alcohol.