Tobacco News and Interesting Information

Marijuana smoking may have a greater potential than tobacco smoking to cause lung cancer, and smoking just one marijuana joint is as harmful to the body as smoking 20 cigarettes, according to a recent study by researchers in New Zealand.

Barrett Duke, vice president of public policy and research for the Southern Baptist Convention's Ethics & Religious Liberty Commission, said the results of the study are "hardly surprising."

"If one burns a substance and inhales the smoke, he is going to increase his risk of lung cancer," Duke said in comments to Baptist Press. "I appreciate the study's recognition that this problem is more acute for those who smoke marijuana. Marijuana smokers inhale marijuana smoke deeply and hold it in their lungs for as long as possible in order to increase the absorption of the drug. It stands to reason then that marijuana smokers would be at a higher risk of lung cancer."

The study, released in the February issue of the European Respiratory Journal, found that marijuana smoke is qualitatively similar to tobacco smoke but contains up to twice the concentration of cancer-causing polyaromatic hydrocarbons.

"This issue is of major public health importance, due to the prevalent use of cannabis globally and lung cancer being responsible for over a million deaths in the world each year," the journal article states. "With the prevalence and mortality from lung cancer increasing, prevention by risk factor modification is of paramount importance."

Marijuana joints tend to be smoked without filters and to a smaller butt size, the study said, leading to higher concentrations of smoke inhaled. Researchers also noted that marijuana smokers inhale more deeply and hold their breath longer, "facilitating the deposition of the carcinogenic products in the lower respiratory tract."

"These factors are likely to be responsible for the five-fold greater absorption of carbon monoxide from a cannabis joint, compared with a tobacco cigarette of similar size despite similar carbon monoxide concentrations in the smoke inhaled," the journal article states.

Researchers conducted the study in New Zealand, they said, because it represents an ideal country in which to study the association between marijuana use and lung cancer.

"New Zealand has a high rate of cannabis use, and cannabis is rarely mixed with tobacco within the joint, as is the custom in the [United Kingdom]," the article said, adding that New Zealand has some of the highest rates of lung cancer in the world.

To conduct the study, researchers questioned 79 lung cancer patients about their alcohol and marijuana consumption, among other topics, and found that the lung cancer risk rose by 5.7 times for patients who smoked more than one joint a day for 10 years or two joints a day for 5 years, after adjusting for other variables, including cigarette smoking.

The researchers said their findings are consistent with three North African studies that have reported a six- to eight-fold increased risk of lung cancer with marijuana smoking.

"Major efforts are being made to reduce the prevalence of tobacco smoking. The findings of the present study suggest that these public health [programs] may need to include greater initiatives to reduce cannabis smoking and should be directed particularly at young people," the journal article says.

Duke said the study "adds one more excellent reason for people to decide against smoking marijuana."

"Not only does the drug severely impair all physical and mental functioning, lead to uses of other destructive drugs, and make users prone to engage in dangerous behavior, it will also increase the likelihood many-fold that the user will experience one of the most feared and excruciatingly painful forms of death -- cancer," Duke said. "There are plenty of reasons to keep marijuana illegal. This study reinforces the health argument."