#5: Link Between Second-Hand Smoke & Lung Caner (Poor Wives!)

This blog is about a study that was done and showed a link between second hand smoke and lung cancer. A cohort study was conducted in Japan to study the consequences to health of factors such as smoking, drinking, occupation, and marital status. In 29 health center districts, 91, 540 non-smoking wives aged 40 and above were followed for 14 years. They were assessed according to the smoking habits of their husbands, and standardized mortality rates for lung cancer were also assessed. The results were that wives of heavy smoker were found to have developed a greater risk for lung cancer than wives of nonsmokers. A 'statistically significant' dose-response relationship was observed. The advantages of using a cohort study are that common exposures can be determined, the sequence of the disease can be established, and multiple outcomes can be examined. With a large sample size, it is very practical for known diseases such as lung cancer.
Second-hand smoke is most definitely an environmental issue- if it weren't, it wouldn't be a public health issue. The definition of environment is all things external to an individual- it can be divided into physical, biological, social, and cultural factors. The basic requirements for a healthy environment consists of CLEAN AIR, clean water, safe food, peaceful settlements, and a stable global environment- emphasis on CLEAN AIR. Just like toxic gases in the air are seen as environmental issues because of the dangers they possess to people and the very atmosphere and environment itself- so are the carcinogens found in tobacco to be perceived. This study illustrates the evident link found between second-hand smoke and lung cancer in a household setting or marital setting. So, the argument can be made that because these women lived with their husbands and almost always with them is the reason why there is a greater risk. But, according to what we learned in lecture this week, when it comes to cancer, there is no such thing as a safe dose. In the dose-response curve for cancer, response equals risk, and a very small dose can increase risk, unlike some other toxins. So, basically allowing tobacco smoke to contaminate the air strips the atmosphere of the requirement for CLEAN air- which is needed for a healthy environment- making it an environmental issue.
This study most certainly supports that second-hand smoke is a cause of lung cancer. According to Hill's Criteria for Causation, a result is more than an association when there is a great strength of association, consistency of association, temporality, a dose response relationship, and biologic plausibility. Association would not equal causation because the results if the study could have been pure chance, the factors could have been confounding (not very likely in this case), and bias. In this study, though chance could have been a significant factor, the rest are not evident because the fact that other cancers and health problems were not seen was noted and that there was a broad range of which the women were selected. The study purposely chose those in urban areas AND agricultural areas. The study also notes that there was a 'statistically significant' dose response observed. According to this criteria and definitions, it can be claimed and asserted that second-hand smoke is a cause of lung cancer.