January 16, 2012

Marijuana Smoke Not as Damaging as Cigarette Smoke

(Ivanhoe Newswire)- In 2009, 16.7 million Americans ages 12 and older reported using marijuana at least once, according to the National Survey on Drug Use and Health. In addition, 16 states and Washington D.C. have legalized medicinal marijuana. Marijuana has become the most commonly used illicit drug in America. A new study at the University of Alabama at Birmingham shows that the consequences of occasional marijuana use does not lead to long-term loss of lung function.

The study's senior author, Stefan Kertesz, M.D., associate professor in the UAB Division of Preventive Medicine and with the Center for Surgical, Medical and Acute Care Research and Transitions at the Veterans Affairs Medical Center in Birmingham was quoted as saying, "with marijuana use increasing and large numbers of people who have been and continue to be exposed, knowing whether it causes lasting damage to lung function is important for public-health messaging and medical use of marijuana."

Long term effects of marijuana have in the past been inconsistent. The researchers used a large national database to compare marijuana and cigarette smokers' lung functions during a 20 year period. While the data revealed that a person's cumulative exposure to cigarettes results in loss of air flow and lung volumes, the same as prior studies, the opposite was proven for marijuana smokers. "At levels of marijuana exposure commonly seen in Americans, occasional marijuana use was associated with increases in lung air flow rates and increases in lung capacity," Kertesz quotes "Those increases were not large, but they were statistically significant. And the data showed that even up to moderately high-use levels – one joint a day for seven years – there is no evidence of decreased air-flow rates or lung volumes." However, the data shows that the relationship changes when people are exposed to a higher level of marijuana smoke over a lifetime, suggesting that there is a decline in lung air-flow rate.

Kertesz and a research team found data from the Coronary Artery Risk Development in Young Adults Study, CARDIA, that recruited 5,000 people of various race, sex, and age to determine the development of cardiovascular disease from 1985- 2006. Kertesz and his team looked at the reported use of marijuana and tobacco and found 37 percent reportedly used marijuana during the study. Participants' lung function was measured for air flow and lung volume at years 0, 2, 5, 10 and 20 using standard pulmonary function tests. Mark J. Pletcher, M.D., of the Department of Epidemiology and Biostatistics, the author of the CARDIA study, quoted as saying, "This is not the first study to show that marijuana has a complicated relationship with lung function. However, the size of the study and the long duration of follow-up help us to paint a clearer picture of the ways in which the relationship changes over time." The study was not intended to show other ways in which marijuana can harm the body. Just the effects to the lungs compared with cigarette smoke.

SOURCE: Journal of the American Medical Association, January 2012