A large majority of my friends smoke cigarettes, and I also work at Chronic Town—a hookah bar downtown—so I’m often around various types of tobacco smoke. It’s odd being one of a few who don’t smoke cigarettes, especially because at this point everyone knows the negative effects of tobacco smoke on our health. But recently, I began to worry that even though I have made the conscious decision to refrain from smoking cigarettes, being surrounded by other smokers may still be detrimental to my own health.
First, let me define secondhand smoke. Secondhand smoke consists of two forms of smoke: mainstream smoke, which is smoke that is released from the smoker’s mouth after inhaling, and sidestream smoke, which is smoke that comes from the lit end of a cigarette. This second type of smoke has larger amounts of carcinogens and also contains smaller particles that are more capable of being absorbed into the lungs and cells of the body. According to the American Cancer Society, when people who don’t smoke inhale secondhand smoke, they are absorbing nicotine and cancerous chemicals the same as people who smoke do, and the more you breathe around this smoke, the more of those chemicals make their way into your body. The American Cancer society also states that secondhand smoke, containing over 7,000 chemicals, 70 of which can cause cancer, definitely causes cancer, even in non-smokers. This, sadly, is believed to negatively affect children whose parents smoke at home; they are at an increased risk for sickness, lung infections, ear infections, and general coughing, wheezing, and shortness of breath.
Furthermore, The American Lung Association states that over 41,000 people die due to secondhand smoke per year—approximately 7,330 from lung cancer and 33,950 from heart disease. I question these facts though because, how can you determine that secondhand smoke was the cause of someone’s death? There are so many factors that go into a person’s death; how can their lung cancer or heart disease definitively be linked to secondhand smoke? It just seems like a stretch to me, especially because they provided no scientific proof.
So I set out to find that scientific proof. This study looked at over 76,000 women and found that there is a strong link between smoking cigarettes and lung cancer, which at this point is a well-known fact, but they did not find a link between lung cancer and secondhand smoke. The study consisted of data from the Women’s Health Initiative Observational Study to look at women between the ages of 50-79 at the time that they enrolled in the study. The studies had data on smoking as well as other related data points such as exposure to secondhand smoke. Out of the 76,304 participants, 901 of them developed lung cancer over a mean of 10.5 years after the initial study. But out of the women who had never smoked, overall exposure to secondhand smoke showed no statistically significant correlation to risk of getting lung cancer. However, women who lived in the same house as a smoker for 30 years or more was associated with an increased risk for lung cancer, but that association was only mildly statistically significant.
The study, however, only covers the link between secondhand smoke and lung cancer, and doesn’t take into account its effects on asthma, heart disease, and other negative consequences that are generally believed to be associated with secondhand smoke. This study seemingly doesn’t actually have that surprising of a conclusion, as it is already largely believed and known that at low exposure levels to secondhand smoke, the risk will not be that great. The study also only looked at women, so we cannot generalize the conclusions to any other gender. In an article in Forbes, the author draws attention to the fact that most of the studies that examined and concluded the strongest associations between secondhand smoke and cancer were case-control studies—studies, a study that compares patients who have a disease with patients who do not have the disease and then look back to factors that could have increased the risk of contracting that disease. This, the author of the article states, could result in recall bias, where people who have a disease will be more likely to recall moments that may have led to that disease, and as we all know, memory is feeble. And out of the 76,000 participants, only 4,000 reported that they had never been exposed to secondhand smoke, so the two groups were incredibly uneven and therefore it’s difficult to show any sort of connection between the independent and dependent variables and also any differences between the two groups.
Multiple researchers also submitted a criticism of the above study, which stated that the study lacked the statistical strength to even detect an association between passive smoking and lung cancer if the association actually existed. Out of the 40,000 women who reported never having smoked, approximately 10% of them—about 4,000—reported no exposure to secondhand smoke and only 152 of them developed lung cancer during the follow-up. These numbers are incredibly small, especially compared to the 76,304 participants, and you cannot draw any hard conclusions, especially one that is so strong and contrary to normal thought, from this small of a sample size. It is also very hard to determine whether someone has actually never been exposed to secondhand smoke, and the amount of secondhand smoke that one has been subjected to is very hard to quantify.
The dissenting researchers suggested conducting a meta-analysis. They cited a study conducted by researchers of the International Lung Cancer Consortium that studied over 2,500 people who had never smoked and found a statistically significant association between passive smoking and lung cancer. However, like I previously stated, this was a case-control study and may have suffered from recall bias. They also stated that an unpublished study that they conducted found statistically significant evidence that there is an association with secondhand smoke and lung cancer. So maybe this suffers from the file drawer problem, because so many people hold it to be true that secondhand smoke is associated with lung cancer that they don’t feel that it’s necessary to publish their findings. They also bring up that studies that research the effect of genes on the effects of secondhand smoke shows that people’s increased risks to the harmful effects of secondhand smoke as it relates to lung cancer differ. They declare that we all should know that there is an association between secondhand smoke and lung cancer and even the most minimal amount of exposure is unsafe.
Given the many shortcomings of the initial study, I definitely would recommend airing on the side of caution and treating secondhand smoke as dangerous to your health. This isn’t to say that you should shun any of your friends who smoke or run every time someone lights a cigarette near you, but definitely be aware of the chemicals that are going into your body and try to remove yourself from the harmful toxins if possible.