We all know by now that cigarettes cause lung cancer, but a new study published in the European Respiratory Journal concludes that smoking cannabis is actually more harmful than smoking cigarettes. When a study like this is published, while it is important to take the information seriously, it’s also important to remember that researchers may or may not have biases.
Marijuana and Cancer Study Background
The study is based in at the Medical Research Institute of New Zealand, because, according to the abstract published in the ERJ, “New Zealand represents an ideal country in which to study the association between cannabis and respiratory tract 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 UK. New Zealand has among the highest rates of lung cancer worldwide with the indigenous Maori population having the highest incidence of any ethnic group. These circumstances provided the opportunity to undertake a case–control study to investigate the association between lung cancer and cannabis use in young people.”
The Politics of the Cannabis Cancer Study
It’s interesting that this particular study is undertaken in New Zealand, and that the study links both cancer and cannabis use with questions of ethnicity. It seems as though the research didn’t begin with the question, “Does cannabis use cause cancer?”, but rather, “Why are lung cancer rates so high among the Maori population?” It is a good idea to keep in mind that there is a lot of political activism in New Zealand centering around marijuana legalization and that much of the statistics cited by these activists state that cannabis use by Maoris is actually no higher than in the general population – although the arrest rate for cannabis use is significantly higher.
Keeping in mind this politicized background for the study, it is also interesting to note that a study conducted in California a few years ago found no links between cannabis use and aerodigestive tract cancers. Since the MRINZ study states that cannabis contains more carcinogens than cigarettes, and that, furthermore, the common practice of smoking cannabis without any type of filtration system exposes the body to more of these carcinogens, it would be expected to find links between cannabis use and other types of cancer, but none have been found.
The Bottom Line
The MRINZ study does acknowledge the difficulty of studying links between marijuana use and cancer, noting that the illegality of the drug, in addition to the tendency for its use to be combined with the use of other substances, can have an impact on the accuracy of results. The study does find a clear link, however, between regular use of cannabis and increased risk for lung cancer. From a common sense point of view, filling your lungs regularly with any type of smoke probably isn’t going to be good for your health.
The study raises interesting questions about how we interpret medical research. Is it ever possible to divorce the results of a study from the political environment in which it is conducted? Is an objective study a viable enterprise?
photo credit: art.cannabis