Smoking and Radiation: The danger no one ever brings up

By | June 8, 2019

Smoking is dangerous and other things

“Smoking is dangerous”, “Smoking can be injurious to your health”, “Tobacco smoke can harm your children”, “Cigarettes are addictive”, “Smoking kills”, “Smoking can cause blindness”, “Smoking can cause a slow and painful death”, “Smoking can cause mouth cancer”, “Smoking can lead to infertility” are just some of the warnings listed on cigarette packs which I can recall of the top of my head at the moment. A good search can lead to a wealth of others, I think. With all this, smoking remains a public health challenge in Pakistan. Having just gone through Ramadan (رمضان) , I recall from my hostel days when a bunch of my friends would disappear around iftar time and could be found huddled on the balconies or corners that acted as make shift smoking dens. Apparently, the urge to expose your system to nicotine was far stronger than the urge for water or glucose. Clearly, in those moments these labels are of little to no value.

Smoking, as a habit runs deep – but this post is not to give statistics on this subject or highlighting in gruesome detail what health challenges are faced by smokers. Plenty has been said in public health videos that frequent the internet. This post is different and is being put together with a specific purpose to introduce people to what causes the damage that is shown on those photos that jazz up the cover of cigarette packs. Again, there are several factors in cigarette smoke that create havoc in the human body, but this post will discuss something that is not frequently talked about. Radiation, yes, but before we talk about that, some background first.

Why Radiation is dangerous?

When one thinks about radiation, the first thing that comes to mind is a nuclear weapon and the ominous consequence that follows its use. Radiation is that invisible agent, to put it simply, that enters the body and damages DNA, the central blue print that controls every function in your body. Damage to this blue print, in somatic cells, can result in runaway biological mechanisms, known as cancers in scientific circles. Other kinds of damages, to germ cells, can result in abnormalities in the subsequent generations. So, you might be saying that this is nothing new, everyone already knows that radiation is bad. How does this connect to smoking? The answer to that will follow shortly. We still need to cover some more background.

Sources of radiation?

Radiation, is a result of physical processes that happen around us all the time, mobile phone usage is one example, background radiation from space is another. These types of radiation are not damaging because they are not strong enough. To understand the strength of radiation we have to introduce a unit, just like the unit of distance is meter, radiation absorbed by humans is measured in sievert (Sv). To put stuff more into context here is a table of radiation-related events and their corresponding doses.

 
Event
Radiation reading, millisievert (mSv)
Single dose, fatal within weeks 10,000.00
Typical dosage recorded in those Chernobyl workers who died within a month 6,000.00
Single dose which would kill half of those exposed to it within a month 5,000.00
Single dosage which would cause radiation sickness, including nausea, lower white blood cell count. Not fatal 1,000.00
Accumulated dosage estimated to cause a fatal cancer many years later in 5% of people 1,000.00
Max radiation levels recorded at Fukushima plant yesterday, per hour 400.00
Exposure of Chernobyl residents who were relocated after the blast in 1986 350.00
Recommended limit for radiation workers every five years 100.00
Lowest annual dose at which any increase in cancer is clearly evident (*) 100.00
CT scan: heart (*) 16.00
CT scan: abdomen & pelvis 15.00
Dose in full-body CT scan 10.00
Airline crew flying New York to Tokyo polar route, annual exposure 9.00
Natural radiation we’re all exposed to, per year 2.00
CT scan: head 2.00
Spine x-ray 1.50
Radiation per hour detected at Fukushimia site, 12 March 1.02
Mammogram breast x-ray 0.40
Chest x-ray 0.10
Dental x-ray 0.01

Keep in mind that the table only lists one time events. A known safe limit is an accumulated 50 mSv per year. Above this limit the chances of adverse effects start becoming significant. For example, 1 full body CT-scan can cost you 10 mSv or 20% of your allowed annual absorption – so 5 full body CT-scans is the most you should get in a year. So here is what we have learned so far

  1. Radiation is bad because it damages the DNA
  2. Different processes/places in nature can expose us to different levels of radiation and a combined dose of 50 mSv is the maximum (according to some estimates) we should be aiming for.

How is smoking linked to radiation?

Figure 1: Another estimate of the amount of radiation received by a smoker’s lungs. The amount of radiation is compared (in order of magnitude, i.e. size of the rectangle) to professions where people come into contact with radiation, namely, everyday radiation under the sky (altitude dependant), CT scan, the damaged Fukushima plant, the US worker limit and astronauts. Astronauts receive high radiations since they leave the protection of the Earth’s atmosphere. All exposures are per year.

Now we are ready to connect this to smoking.  Cigarettes contain numerous (~7000) entities, of which an estimated 250 are dangerous of which 69 are known carcinogens (cause of cancers).  One of the ~7000 known entities is polonium-210, which is radioactive. This element releases a special type of radiation, which can only travel a very small distance. This means that this kind of radiation cannot cross our skin. However, when polonium enters our lungs, through cigarette or second-hand smoke, and subsequently irradiates surrounding tissue, that is a different story. Since the bulk of 7000 compounds destroys the body’s cleaning system, polonium begins to build up and as a consequence the exposure of human tissue to radiation keeps increasing.

OK. So we looked at radiation and we say how one of the compounds in smoke is radioactive and collects in the lungs of the smoker, irradiating the lung tissue. Let’s try to contextualise this. First, its important to note that the safe limits set by international organisations are for full body exposure and NOT for localised exposure as is the case of decaying polonium which only effects the tissue immediately surrounding it. So perhaps its not fair to convert localised exposure and compare to full-body exposure, as avoided by earlier studies. A gross estimate, if attempted would be that a smokers lungs receive ~10 times more radiation than a non-smoker or in other words approximately 300 chest X-ray per year. That is a lot of chest X-rays, and puts a smoker between the two red * symbols in the table.

A public health message

These are obviously tentative numbers and estimates vary a lot. Individuals differ as well, so not everyone behaves the same way to cigarette smoke. However one thing is for sure. A smoker in Pakistan, with the current levels of pollution in cities like Lahore and Karachi is definitely worse off. Remember that the effects of multiple factors is compounded, so two factors will damage the lungs more than each of them acting alone. Between cigarette smoke, dust, pollution from incineration of waste and automobiles, these factors working together are definitely more than sufficient to cause problems, adding more challenges to an already crippled healthcare system. Prevention is always better than cure. If you don’t have cancer or other lung problems yet, quitting now will definitely improve your chances of not getting them. If you think you are not effected by smoking, that is wrong. The smoker’s cough is the first symptom of many things to come. It’s the body trying its best to clear the lungs. Seek help now, before its too late.

Sources:

Wikipedia:

https://en.wikipedia.org/wiki/Health_effects_of_tobacco

Others:

http://www.rmeswi.com/36.html
https://www.theguardian.com/news/datablog/2011/mar/15/radiation-exposure-levels-guide

Additional reading:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3857029/
https://www.ncbi.nlm.nih.gov/pubmed/7088089
https://scienceblog.cancerresearchuk.org/2008/08/29/radioactive-polonium-in-cigarette-smoke/

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