Is smoking really harmful? Aren’t the studies that say it is biased?
Question received by email, possibly calculated to make steam come out of my ears.
This question is worth answering if just to make the point that yes, there are biased studies out there, and also studies that just aren’t that well designed. That’s why publication is a key part of science in this day and age: we can check each other’s working. That’s why recording every step of an experiment or study is important, and why you have to communicate your results clearly — all of your results, and not just the ones that suit you. When you read about some big study proving such-and-such, you need to look at who conducted the study as part of reading it. Do they have a vested interest in ensuring that people think something is safe, or unsafe, or effective, etc? Do they need a certain result from their study?
It’s true that companies involved in the sale of tobacco products produced studies which showed that smoking was not harmful. But look at the source: companies involved in the sale of tobacco products have a vested interest in claiming that their products are not harmful. By contrast, others have little to gain. It’s also worth noting if they declare a conflict of interests.
I will add here that I myself dislike smoking and think it’s a dangerous and unpleasant habit. I have had family members that smoke, and have lost family members to cancer. Like any source, I have a bias which is worth considering, even though I attempt to restrict myself to pure fact.
To answer the first part of the question, yes: smoking really is harmful. Everyone has or knows of someone’s aunt who has smoked like a chimney since she was eleven and runs marathons every other weekend, or something like that; there are some lucky people who aren’t badly affected. That’s all it is: luck. Good genes, and a large dollop of chance.
Nicotine itself, the active ingredient in tobacco that people are seeking out, is a poison. People who harvest tobacco can fall sick with “Green Tobacco Sickness” — they are poisoned by absorbing nicotine from wet tobacco plants through their skin. The symptoms include nausea, vomiting, dizziness, difficulty breathing and abdominal cramping. It will usually resolve on its own, but may require hospital care. As you can guess from this, the amount of nicotine you consume while smoking is unlikely to be able to make you ill, but large doses of nicotine can be poisonous and honestly, “it doesn’t do permanent harm” is not exactly a ringing endorsement. Ingestion of a large dose can cause seizures and respiratory failure.
The other issue, and one probably better known, is the tar in tobacco products. Tar sticks to the cilia in your respiratory system that are meant to sweep out harmful substances and keep things clear. That’s why you’re more likely to get infections if you smoke: your body simply doesn’t provide the vital first barrier to infection that is part of your innate immune system.
Tar is just one of various harmful substances in the smoke, including carbon monoxide, formaldehyde, hydrogen cyanide and arsenic. Even if none of those substances ring alarm bells, it’s worth considering the carcinogenic effects of many of the substances in tobacco smoke. Carcinogens provoke changes in your cells which can break DNA and disrupt metabolic processes. Often, the human body can repair such damage. Sometimes, it cannot, and the damaged cells can begin to proliferate out of control. This can eventually form a tumour, which can eventually metastasise and cause cancer in other parts of your body. The brain is a common secondary site from lung cancer — though you should remember that the lungs are not the only site the carcinogens damage. The mouth and throat are affected too — anywhere the smoke comes in contact.
Even in the course of everyday life, our DNA gets damaged, and though it needs to be damaged in several critical places at once to cause cancer, that can easily happen over the course of a lifetime — whether you smoke or not. I prefer not to take the additional risk, especially when it’s as manifestly obvious and well publicised as that of tobacco products.
If you don’t believe in the risk of smoking as a whole, try looking up individual aspects of smoking — tar, carbon monoxide, formaldehyde, lead… Even isolated from an agenda around suppressing the incidence of smoking, you will find many of these ingredients are harmful to humans. This is another way you can check bias: look to see if the results of a given study are supported by other, unrelated studies. In the case of smoking, you will find that they are.