This is the first in a series of blog posts on radiation. With all of the hype in “crunchy” circles about the dangers of low intensity radiation, Ezra and I wanted to do research on it and come to conclusions that were based on science as much as possible and not on the hype.
This first article is written by Ezra, who studied a lot about nuclear systems, specifically for reactors, in university and in preparation to possibly work with submarines after. The purpose of this post is to define some terms we’ll be using later and establish some of what we DO know for certain before we move on to areas that we (and many others) know much less about.
A Short Discussion of the Known Properties and Dangers of Radiation
The term “radiation” is used for many different types of particles or waves which are “radiated” from various substances. For the purpose of this discussion, I will make a broad division between two different kinds of radiation: radiation which has enough energy to cause damage to human cell tissue and radiation which does not. This discussion will focus almost entirely on the “higher energy” radiation, because it is responsible for all known, studied, and measured negative radiation-related health effects.
Four of the most notable types of radiation are gamma, alpha, beta, and neutron radiation:
Name Particle (Charge) Penetration Ability Damage Potential
Alpha Two neutrons and two protons (+2) Almost none Large
Beta One electron (-1) Very little Medium
Gamma One photon particle/wave (0) Medium Medium
Neutron One neutron (0) Considerable Small
Alpha particles occur naturally, so that everyone is exposed to some (typically very small) amount of alpha radiation during their lives. Due to their large size and charge, they can do a relatively large amount of damage to human cells. However, these same properties make them extremely unlikely to penetrate the human body beyond the very outer layer of skin, so that they are only dangerous if ingested in large quantities. Interestingly, the amount of alpha radiation in an area can increase slightly with the weather phenomena known as temperature inversion.
Beta particles typically do somewhat less damage than alpha particles, but also can penetrate a little bit further into the body. However, they can still be stopped by a thin layer of clothing, and therefore cause only surface burns unless they are ingested.
Neutrons do not occur naturally in large levels. Also, because they have no charge, they can travel right into the human body, or even through the human body without interacting with it at all. Neutrons are the type of radiation which sustain nuclear reactions, both in power plants and bombs. This is why nuclear power plants employ multiple thick layers of water and lead shielding; utilizing these types of shielding reduces the amount of radiation emitted from a functioning power plant to less than normal natural radiation levels.
Gamma radiation is the most commonly encountered radiation. The particle (or wave) which forms it is the photon. In other words, light is gamma radiation. Visible light itself is does not have high enough energy to cause radiation damage to cells (although the sun’s rays may contain non-visible photons that can cause damage). However, photons of higher frequencies (which means higher energies) can. Also, photons will often penetrate deeply into the human body before colliding with human cell tissue.
It is important to understand that there are two completely different effects that these types of radiation can have on the human body, which must be discussed separately in order to be understood correctly. These are known as acute effects and chronic effects.
To understand acute effects, imagine your body being bombarded by thousands of molecular sized particles, and then repairing the damage caused by those particles. That would describe how your body normally deals with background radiation. Acute radiation effects would begin when your body can no longer repair damage done by those particles colliding with your body. When a cell in your body’s tissue cannot repair itself fast enough to keep up with radiation damage, it begins to die. If enough cells die, your body will begin to lose its ability to function, which can result in death. There are very few examples of this in real life; aside from nuclear weapons, Chernobyl, and a few military and scientific experiments gone wrong, these effects generally do not occur. Radiation levels simply are not high enough to produce acute effects in most cases, even when they are high enough to produce chronic effects (Three Mile Island and Fukushima both did not release nearly enough radiation into the atmosphere to cause acute effects). Note: most Hollywood portrayals of “radiation sickness” are based off of acute radiation effects.
Chronic radiation effects result from radiated particles passing through a cell’s membrane and colliding with the DNA in a cell’s nucleus. This has the potential to alter the DNA, which can cause deformities and cancer to show up at a later time. Because cells cannot repair themselves from damage to DNA, chronic effects are cumulative, meaning that a low intensity of radiation over a long period of time can have the same chronic effect as a high intensity of radiation in a short period (as opposed to with acute effects, where the intensity of the radiation is what matters more). So then, everyone receives a chronic dose of radiation which accumulates over their life time from various every-day sources, both natural and man-made.
It is useless to worry about trying to eliminate the sources of radiation which accumulate into this chronic dose; they include the sun, dirt, rocks, trees, bananas, building materials, some medical procedures, and most other things encountered in life. While some of these things are unavoidable, such as dirt and trees, many which are avoidable provide benefits which far outweigh the added risk. Following are some common avoidable sources of radiation:
Name Increased Radiation Exposure Potential Benefit
Bananas Minimal, from potassium Health
Medical (isotope, x-ray) Moderate More accurate diagnosis
Flying Moderate Quick travel
Nuclear power plants Minimal Economical power
Cigarettes Significant Enjoyment
Cigars Moderate Enjoyment
It would be silly to stop eating bananas because they contain more radiation than most fruit; they provide enjoyment and health benefits which far outweigh the insignificant amount they contribute to an individual’s chronic dose. Medical procedures which use x-rays or isotopes are worth a bit more thought; they can represent something like a tenth to a sixth of an average person’s annual chronic radiation dose. However, in most cases, the benefits of medical radiation also outweigh the risks. The same might also be said of flying.
Nuclear power plants are a hotly debated subject when it comes to radiation exposure. I will simply add my thoughts to this debate by saying that while nuclear power plants do pose some health risk, so do all other forms of large-scale power generation, both traditional and alternative. A discussion of exactly what these risks are, or how they stack up against each other would be long and complex and beyond the scope of this writing. However, as a person who has studied nuclear power plants in-depth, I will simply say that I would have no qualms living next to an American nuclear power plant, that living next to a nuclear power plant will not increase your annual radiation dose, and that the benefit of having nuclear power plants is most certainly worth the risk.
Cigarettes are a significant contributor to the annual radiation dosage of anyone who smokes on a regular basis. Typically, for a chain-smoker, cigarettes will contribute more than any other factor. The reason for this is that the cigarette smoke will leave particles behind in a person’s lungs which will continue to radiate into that person’s body for years. Two other points regarding cigarettes: first, since the smoke from a cigar (or pipe) is not breathed into the lungs, cigars are significantly healthier, so that a person who enjoys a moderate amount of cigar smoking may reasonably deem the enjoyment worth the risk. Second, the radiation dose accumulated by cigarette smoking is a much smaller health concern than the volume of smoke dust particles accumulated in the lungs.
One more big concept worth understanding is the difference between radiation and radioactive contamination. Radiation refers to the actual particles or waves which have been emitted from something else, and which will normally travel in a straight line until they collide with something or are absorbed by something. An individual particle of radiation generally exists for an extremely short period of time. Radioactive contamination is any substance which contains unstable atoms which can decay in a process which emits radiation. Thus, radiation comes from contamination. When a news anchor reports that “radiation” was released from Fukushima, what they actually mean is that contamination was released. This is significant, because contamination will continue to cause radiation for a period of time after it is released (though, in the case of Fukushima, it will likely be found that the increase in background radiation caused by the accident will be minimal or even negligible).
Finally, it is worth ending this discussion with a word about lower energy radiation (the kind without enough energy to contribute to cause direct harm to the human cell). I have done my best here to lay out the dangers of higher energy radiation as they are: dangers worth considering, but in many cases, risks worth accepting. What I cannot speak intelligently about are the emerging claims that low-energy electromagnetic radiation, such as that which is emitted from cell phones and wi-fi hot-spots, may effect the function of the brain, or may interfere with hormone levels in the body. Such a thing seems possible to me, but my knowledge of neuroscience is insufficient to give anything like an educated opinion on the matter. My only concern is that the risks associated with higher energy radiation are often confused with the conjectures being made about lower energy radiation, an unhelpful situation which often leads to unnecessary fear or the sale of expensive and dubious products, falsely marketed as scientifically tested ways to protect an individual from being harmed by low-energy radiation.