by Paul Herscu, ND MPH
April 5, 2011
In light of recent occurrences in Japan, we have received numerous questions on the topic of radiation. What seems in order is a quick primer on radiation in general.
This particular writing is designed to provide more complete information to those wanting to understand where the Japanese nuclear emergency fits into the larger topic of radiation. The first part represents a condensed overview describing radiation, both non-ionizing and ionizing. The second part begins the discussion on the Japan power plant crisis of 2011, first describing what happened, but more importantly, placing it in context.
Radiation, or electromagnetic radiation, surrounds us all the time, classified as either natural or artificially produced. In either case, electromagnetic radiation can be thought of as energy chunks called photons, which are easily characterized by looking at both wavelength and frequency. And to be specific, the energy of a photon is proportional to its frequency and measured by volts. More specifically, electron volts (eV) are described as “the energy that an electron acquires in being accelerated across an electrical potential difference of one volt.” As an example, lower energy photons, like electric fields, have frequencies of 1 -103Hz and their energies only a tiny fraction of one eV. Intermediate energy photons like those of visible light, which is the only form of radiation felt or seen by humans, have frequencies of 10-2 -10eV and energy of 10-12 -1015Hz. By contrast, higher energy photons, which are exemplified by cosmic rays, can have frequencies of 1021 hertz or cycles per second and their energies measured at 107 eV.
By the nature of the energy form, importantly, high energy photons can penetrate matter and that is where problems develop. As a result, as radiation moves through space, it interacts with atoms it encounters, but only photons in the higher energy range like cosmic rays, x rays, and gamma rays have enough energy to ionize atoms, by stripping away electrons orbiting the atoms, and are therefore called ionizing radiation, creating ions. By the removal of electrons from an atom, an unstable atom is created, and is positively charged, called a free radical, which has potentially negative, biological effects. The other form of radiation is too weak to strip away the electrons and are therefore called non-ionizing radiation. Among these would be microwaves, infrared, and radio waves.
Source: Environment, Health and Safety Online http://www.ehso.com/ehshome/cellphonecancer.php
Nonionizing Radiation: While nonionizing radiation is much less dangerous to us, it should be understood that it does have some effects. Below, I highlight 5 forms of nonionizing radiation.
1. Ultraviolet radiation (UVR): Themajor source is the sun, but also electric lights and tanning lamps. The sun’s UVR is blocked by the atmosphere, in part, meaning that the higher elevation one is on this planet, the less atmosphere and therefore more UVR one may be exposed to. High short-term exposures can cause fever, nausea, and malaise; chronic effects may cause ‘aging’ skin, and premalignant or malignant changes to the skin. It may cause or trigger malignant melanoma, rates of which doubled in the last quarter century. Tanning salons, another source of UVR, increase rates of both squamous and basal cell carcinoma.
2. Visible Light and Lasers: Lasers and visible light can cause retinal burns. An example of visible light danger would be when looking at the sun directly, as during an eclipse.
3. Infrared radiation: Infrared radiation is emitted from hotter surfaces to cooler surfaces, like from the sun to the earth or in cooking surfaces. Infrared does not penetrate deeply into skin though it does produce what we feel as a sensation of heat. This warns us of a potential problem, skin burns; over time, in some, infrared can cause cataracts. The bottom line on all these types of visible spectrum radiation is that they cause the skin to redden and can cause burns and tissue damage, though most is at the skin level and just below it.
4. Microwave radiation: These are found in radar, radio, television, telecommunication, and microwave ovens. Found in many homes these have become commonplace and are very similar to one another. Due to the property of this radiation, it is supposed to be more or less inert, if exposure is regulated, as in using a microwave correctly. In the lower ranges, it has little susceptibility to living systems, but as the frequency increases, it is absorbed more easily. At higher energy in this group, such as microwave ovens, which add energy to water molecules making them move faster and heat is the byproduct. Cell phone use also creates this form of radiation, which is supposed to be safe, though more recent research puts this in question, as cellular changes have been noted by prolonged cell phone usage.
5. Electric and magnetic fields: Electric fields are developed when the net balance of the atoms in an area are no longer balanced between positive and negative charges and are therefore no longer neutral, like when you have static in your hair. Magnetic fields can be generated by creating electric fields within a wire and are within a short range from where they are produced. The earth itself makes a magnetic field. There is discussion on whether these fields cause health hazards, such as cancer, but this has not been tested definitively.
So what we find is that the higher the energy, the higher wavelength and frequency, the more dangerous the radiation is and the more likely it is to produce cellular changes.
From Ionizing Radiation http://info.lu.farmingdale.edu/depts/met/ind310/ionizingradiation.html
Ionizing radiation:This is the form of energy that creates the most potential risk and damage and is the form that we often think of when we talk about ‘radiation.’ The common unit of radiation is called the Sievert (Sv), which is an equivalent dose, equal to 1,000 mSv. It is a term that can be used for all ionizing radiation, specifically measuring radiation which is absorbed by a person. This is calculated by multiplying the absorbed dose by a weighting factor, which is determined by a combination of standards such as which tissue has been exposed and the form of radiation exposure. As mentioned above, this includes x rays, gamma rays, natural radiation and human made radiation, described below.
Natural background radiation: We are constantly exposed to natural radiation in two forms: natural occurring earth radiation and cosmic radiation. Cosmic radiation gives an annual dose of .3 mSv at sea level. The atmosphere partially shields us from cosmic radiation. However, as we climb, the dose is higher. At 1 mile up in elevation, the dose is 0.5 mSv per year, at 12,000 feet it is 1 mSv, at 30,000 feet (Jet plane elevation) it is 45-70 mSv, at 50,000 it rises to 80-90 mSv year, and at 65,000 feet, it is 100-175 mSv per year, which is where future supersonic planes are going to fly in the not too distant future. However, since we (hopefully!) spend only short periods of time on airplanes, one only receives hundredths of a single mSv. This is different for airplane crew. Long range airplane crew gets 5 mSv per year exposure, which is higher than commercial nuclear power plant workers in the United States. Regarding terrestrial radiation-from radionuclides in soil, the value varies depending on where one lives. In some places in the States, for example, where there is excessively sandy soil, the range is a few tenths of one mSv. However, in some areas, like near ground uranium deposits, it can be as high as 1mSv a year.
Radon: One form of significant earth radiation comes from Radon, common in many homes, which may add 16 mSv to the lungs as it is inhaled. To be sure, the most significant form of radiation exposure to an average person is from this one sort of exposure. When uranium decays, one thing it produces is this unnoticed, cancer- causing gas which is radioactive, producing the worst alpha versus the lesser gamma particles, and alpha radiation penetrates the body more readily. This gas enters the lung and is one of the most known contributors to lung cancer.
This puts the total dose from natural sources-at 2.2-2.4 mSv per year on average, with 33% from cosmic/terrestrial and around 66% from radionuclides deposited into body. In the States, total background natural exposures ranges from less than 1 mSv in radon free house in coastal free radon areas, to as high as 5-20 mSv in the high plateaus of Colorado, near places where uranium is found in the ground.
Human generated radiation: Total nuclear weapons testing has released to the world about 0.4 mSv of external (skin) exposure and .6 mSv of internal (inhaled) exposure for a total of 1 mSv dose up to the year 2000. This is calculated such that you amortize the total release over the span of 50 years for the average person alive during these years! It is hard to believe that someone actually sat down to do this calculation, but it has been done! Clearly, this exposure was greater if the person was actually near the release or downwind from a test site.
Radiation is used in many forms for medical applications, such as X-rays and CT scans, as well as for security reasons like going through security stations in airports; it is likewise found in smoke detectors. This material released into environment totals about 0.4 uSv per year, which is not so much. Nuclear power plants are a big issue. Economically, they generate 20% of United States energy and 30% of world’s energy. There are about 100 plants in the USA and around 400-500 plants in the world, with another 150 or so used in military settings, such as for propulsion for submarines.
A very high cause of internal exposure comes from tobacco, which contains 210Po, a naturally occurring radionuclide. It is considered one of the most hazardous materials on earth. As an example, smoking 1.5 pack/day translates to a 160 mSv dose of radiation to the lungs.
Radiation Control Methods
The main concept around protection when relating to radiation is captured by the concepts of Time/Distance/Exposure. The greater the time of exposure, the worse the potential outcome. The closer one is to the exposure, the higher the risk. The more exposed one is to the radiation, the more one is at risk. Therefore, the rule of thumb has been to remove oneself from the area, to limit the time of exposure, and to shield oneself as best as possible in order to limit exposure. Here shielding refers to everything including limiting radioactive food.
II. RADIATION: Japan Power Plant Crisis 2011
1. March 11, 2011: The 8.9 magnitude earthquake occurs around 80 miles off the coast of Japan. Based on fail safes in place, this triggered all 11 Japanese reactors to automatically shut down. Fukushima Daiichi power plant had 6 reactors, but reactors 4, 5, 6 were shut down prior to the earthquake for maintenance and inspection. This means that only 1, 2, and 3 went through the emergency shutdown. The shutdown, as well as trying to use emergency generators, caused reactors 1 and 2 to have pressure build up as cooling systems failed.
2. March 12, 2011: Tokyo Electric Power Company decided to release some of the pressured steam into the atmosphere to reduce the pressure inside reactors 1 and 2. This release, contained small amounts of radioactive material, which was later identified as celsium-137 and iodine-131. Unfortunately, an explosion in the plant collapsed the concrete building around the reactor 1 container. The unit was showing overheating and it was decided to pump in seawater mixed with boron. From prior failsafe plans, an evacuation alert evacuated people from 10km radius around the plant.
3. March 13, 2011: Unit 3 cooling system failed as did the other 2, and likewise celsium-137 and iodine-131 containing steam was released into the atmosphere, and seawater injected in. Radiation levels were above safety limits at the plant, above 1,400 mSv.
4. March 14, 2011: Preparations were underway to begin injecting seawater mixed with boron into unit 2 reactor, secondary to low water levels. On the same day, reactor 3 also exploded. However, no damage was done to its containment vessel.
5. March 15, 2011: An explosion occurred at reactor 2 releasing nearly 1,000 mSv per hour, which at the same time damages the roof of reactor 4, which was offline at the time of the earthquake. This causes the government to evacuate a 20 km radius of people and to announce warning to all those within 30 km. At the same time, Tokyo experienced ten times their typical level of radiation. On this day, a new major threat occurred. Fire was discovered in spent fuel rods storage pond in reactor 4. This was very bad news since a fire could release a great deal of radioactive material directly into the air.
6. March 16, 2011: Reactor 3 released white radioactive steam into the atmosphere, from heated spent fuel pool, due to a breached containment system. The United States removes all United States personnel from a 50 mile radius of the plant.
7. March 17, 2011: Helicopters deliver seawater dumps to reactor 3. Unit 5 and 6 begin to heat up in their spent fuel pools, as reactor 3 begins to see increased pressure.
8. March 21, 2011: Electricity is restored in half the unit reactors, with the cooling system working in reactor 5 and 6. Radiation remained at over a thousand times above the normal limit. While reactors 1-3 may have core damage, the belief is that the containment systems are not currently breached.
9. Ironically, at another close site, on day 1, fire was found at the Onagawa nuclear reactor plant. This was put out and while originally there was thought to be radiation leaks there, it was later realized that the radiation came from the Fukushima plant. I say ironic, because since the tsunami wiped out much of Onagawa, the residents have found that the safest place to live, temporarily, is at the nuclear facility itself, due to its sturdy construction.
10. The New York Times at the same time reported the following: "The principle elements that have been released from reactors at the Fukushima Daiichi plant are iodine 131 and cesium 137. Cesium is dangerous because it is long-lived and travels easily through the food chain, continuing to emit particles for centuries once it is released." "While iodine 131 is much shorter lived — its radioactive potency is halved every eight days — it is dangerous because it concentrates in the thyroid gland, resulting in high radiation doses to that vulnerable organ."
11. Radiation has been found in water and vegetables and will, without quick controls, likely to be found in North America in the coming days and weeks.
12. I am including a link to the actual records, by region, in Japan for radiation. Note that this is monitored and changed frequently and can give you a sense of the actual real numbers found. Look by date and location. http://eq.wide.ad.jp/files_en/
Considerations and Conclusions:
At this time it does not seem to be a global scare, like that witnessed with Chernobyl. While the release in Chernobyl was over a wide area and contained scores and scores of different radioactive molecules, thus far that does not seem to be the case with the Japanese incidents. As reported thus far, only 2 isotopes have been identified, which brings me to the next point, honest communication. I want to focus on this part in the next update. Without any major new leaks, without new fires, explosions, containment breaches, fuel rod breaks, and without new molecules being discovered, this tragedy may remain local. A tragedy on massive proportion, mind you, but local to Japan, though the economic effects for limited raw resources will of course, impact each of us over the next many years.
The bottom line is this: while one cannot remove completely the exposure to radiation, one could limit it. The two most likely radiation causes we can potentially be exposed to are radon and cigarette smoke, two things that can be mitigated by behavioral environmental choices.
In other words, stopping smoking and checking your home for Radon are the biggest changes you can make to reduce exposure to radiation. In non smokers, 82% of exposure is background radiation. Of the rest, protect one’s skin to exposure to the non ionizing radiation, and limit exposure to ionizing radiation in the day to day. To sum up then, for the overall world, the effects of the Japan radiation release is minimal at this time to the world’s health, though of course very different in Japan itself. However, for people in Japan, ionizing radiation may impact people locally both acutely and chronically. For the rest of you, stop smoking, and check for Radon. This may not capture your imagination and fear, but it is so much more important to you and your family’s health. A fuller consideration of what to do about the radiation, as it flows over the US, as well as a plea for honest communication needed from the government will be sent in the next update in the coming weeks. I will put together a full reference list for those who want to read more about this topic, and to understand it in context.