Sunday, March 20, 2011

Putting Radiation Risk into Perspective

There has been quite a lot of fear and speculation about the risk of radiation exposure for those of us living in California, Oregon, and Washington. That fear has led to such a rush of folks buying up IOSTAT potassium iodide supplies that there is fear that there will be insufficient potassium iodide for those folks in Japan who are at the highest risk of radiation exposure. The news reports vacillate between warning of imminent doom and telling us to not worry our pretty heads about it, and neither perspective seems to be terribly useful. But given what is happening in the world today, what do we actually have to be afraid of? And what steps can we take to protect ourselves and our loved ones?

What is Radiation? What’s the Risk?

To understand our risks, it helps to start with a basic understanding of radiation. All matter is made up of tiny particles called atoms. Some atoms are unstable. As unstable atoms shift to become more stable, they give off waves of energy, called radiation. There are different types of radiation, and varying levels of risk associated with different types. One type of radiation, called non-ionizing radiation, creates enough energy to move atoms but not enough to change them chemically. This type of radiation includes visible light, radio waves, and microwaves (cell phones, which work using microwaves, would be included in this type of radiation). The other type of radiation is ionizing radiation. This type is capable of pulling electrons off of other atoms, and can cause cellular damage including damage to our DNA. (information from the EPA website)

According to the National Council on Radiation Protection and Measurements, there is no measurable increase in risk for cancer or any other biological effects of radiation exposure up to 14 millisieverts (mSv). It isn’t until we reach exposures of 500 mSv or higher that we begin to see a decrease in blood cell counts and an increase in cancer rates at 1 person in 250. To put this into perspective, levels as high as 400 mSv per hour have been registered at the Fukushima plant itself, and a few hours of exposure to this dose-level can cause radiation sickness. For long periods since the crisis began, the BBC reports that levels have been at 10 mSv per hour or lower, and Monday morning the level was around .02 mSv per hour. These measurements are at the damaged plant itself. In Tokyo, radiation levels have been reported at as high as 12-13 mSv, which is higher than normal for that city but still far below what is considered to pose any health risk (according to Green Peace).

The danger associated with radiation exposure results from direct inhalation of a radiation plume. For us here in the US, it is possible that some radioactive material may end up in Hawaii, Alaska, or the West Coast. But as things stand as I am writing this article, by the time any plumes reach us they will most likely be so diffuse that they will not cause a significant health risk to anyone in the US, according to sources such as the BBC, the EPA, the Union of Concerned Scientists, and others. It is worth noting that ongoing low-level radiation exposure does have a cumulative effect on the body as well. The risk posed by a cumulative effect will be determined by factors such as the level of ongoing exposure, the duration of exposure, and your own body's ability to heal damage and clear radiation.

Many people are discussing the use of iodine as protection from nuclear fallout. The reason for this is because radioactive iodine (known as Iodine-131) is one of several possible radioactive contaminants released during a nuclear fallout. However, Iodine-131 is not the only radioactive material to be released in the event of a nuclear fallout. Other radioactive contaminants found in trace amounts from the power plant in Japan include Cesium-137 and Strontium-90.

Iodine: What is it? How does it help?

Iodine itself is an essential trace nutrient that the human body uses to manufacture thyroid hormones. The US recommended daily dietary reference intake (DRI - this has replaced the old RDA or recommended daily allowance) for iodine is between 110 and 130 mcg (micrograms) for infants up to 12 months, 90 mcg for children up to eight years, 130 mcg for children up to 13 years, 150 mcg for adults, 220 mcg for pregnant women and 290 mcg for breastfeeding women. The Tolerable Upper Intake Level (UL) for adults is 1,100 mcg/day (1.1 mg/day). The “DRI” recommendations are the smallest amount of a nutrient a person can take and still avoid developing a deficiency-related illness. The “UL” is the maximum amount that most people can safely take of a nutrient without developing toxicity symptoms.

The dosage for potassium iodide that is recommended in the case of a nuclear fallout is determined by age, weight, and level of radiation exposure. Dosage for exposures greater than 50 mSv, children up to 1 month: 16 mg; 1 mo.-3 yrs: 32 mg.; 3 yrs-18 yrs (or under 150 lbs.): 65 mg. For exposures greater than 100 mSv, adults age 18-40 yrs: 130 mg. And for exposures greater than 500 mSv, adults over 40 yrs: 130 mg. That high of a dose should last in the system for several weeks, and should only be repeated if there is explicit instructions by a health agency to repeat the dose.

Notice the extreme contrast between what is considered a safe upper intake limit for iodine for an adult (1.1 mg) compared to the dose recommended for nuclear fallout protection (130 mg). This is a tremendous difference, and there are some health and safety risks involved with taking such a high dose. The 130 mg dose is what's called a "loading dose", meaning you take this dosage once, and it should protect you for up to 2 weeks in the event of a nuclear crisis. This is not a dose you repeat, unless the radiation levels continue to stay high two weeks later or unless a health agency informs the public that additional doses are necessary. Iodine-131 is a radioactive form of iodine, and is one of several radioactive materials that may be released during a nuclear fallout. The reason you take such a high loading dose of (non-radioactive) iodine is because the thyroid is constantly using iodine, and the huge loading dose enables your body to be so oversaturated with non-radioactive iodine that it basically outcompetes - the radioactive iodine doesn't have anywhere to bind because the thyroid is already saturated with iodine.

Health Risks Associated with High Doses of Iodine

There are some health risks to watch for if taking such a high dose of iodine. For one thing, some percentage of the population is actually allergic to iodine, and may even go into anaphylactic shock from ingestion at this level. If you have a known iodine allergy, this is going to be a problem for you, and you may want to consider alternative protective measures. Those with shellfish allergies should proceed with caution as well, since some percentage of those with shellfish allergies are actually allergic to the iodine in the shellfish.

Another thing to know is that excess iodine may exacerbate both hyperthyroid and hypothyroid conditions - if your thyroid is already sensitive, taking such a high dose of iodine may cause serious problems for you. For some people even without preexisting known thyroid problems, excess iodine can cause hyperthyroid symptoms as the thyroid begins making too much thyroid hormone. The thyroid controls metabolic rate for every system in the body, and if the thyroid overproduces, it causes every body system to speed up, so symptoms may include racing pulse, heart palpitations or arrhythmias (even atrial fibrillation), nervousness, irritability, tremors, sweating, trouble sleeping, high appetite, rapid weight loss, hair loss, hypoglycemia, diarrhea, vomiting, muscle weakness, and other symptoms. In some cases the high dose of iodine can actually knock the thyroid out completely, resulting in a hypothyroid condition. Hypothyroid symptoms include fatigue, muscle weakness, sudden and unexplainable weight gain or water retention, sore joints or muscles, difficulty controlling body temperature, hair loss, constipation, anxiety or depression, and dry itchy skin.

What else can I do to protect myself?

Your personal level of risk for radiation exposure of any sort is somewhat dependent on your current health and overall nutrient level. If you eat a good diet, take decent quality vitamins, exercise, and generally are in good health, even in the event of a radiation exposure, your risk levels will be lower than someone who doesn't take care of their health. If you are looking for natural ways to protect yourself in the (hopefully unlikely) event of a radiation exposure, now would be a great time to up your intake of fresh fruits & veggies, whole grains, legumes, and healthy animal foods, start a decent quality multivitamin (centrum and costco generic multivitamins don't actually count - most of the cheaper multivitamins aren't very well absorbed), and get enough sleep. Avoid foods and lifestyle habits that can weaken the body or exacerbate poor health, such as processed and refined starches, added sugars, hydrogenated fats, smoking, excess alcohol, and poor sleep. Most of us do have a sense of what constitutes health-supporting diet and lifestyle habits. If you have been considering reducing your soda intake, increasing your veggies, or cutting out the fried foods, now would be a great time to start.

There are some specific foods that may be cell-protective in terms of radiation exposure. These foods include seaweeds, spirulina, chlorella, natto (Japanese fermented soybean product), and miso soup. In 1945, there were several compelling anecdotal stories in Japan on the use of macrobiotic diets to protect patients in Japanese hospitals after the atom bomb was dropped on Hiroshima and Nagasaki. Dr. Tatsuichiro Akizuki, M.D., was director of the Department of Internal Medicine at St. Francis’s Hospital in Nagasaki. He fed his patients and his staff a strict and simple macrobiotic diet consisting of seaweed, miso soup, Hokkaido pumpkin, brown rice and sea salt with strict prohibitions against sugar. In his hospital, there were no severe radiation symptoms seen among the patients or the staff while folks in hospitals further from the bomb site had far more symptoms and higher mortality rates (Tatsuichiro Akizuki, M.D., Nagasaki 1945 (London: Quartet Books, 1981); Tatsuichiro Akizuki, “How We Survived Nagasaki,” East West Journal, December 1980). This story and others like it prompted studies to be performed in Canada, Japan, and Russia, all showing beneficial results when using seaweeds and miso paste to reduce radiation levels from tissue.

Another factor one cannot underestimate in terms of overall health impact is the health impact of stress and fear. These are scary times, and many people are very nervous about what a possible nuclear fallout may mean for themselves, their loved ones, and our world at large. While fear is an understandable reaction to the situation in Japan, the fear itself may cause more health damage than the actual radiation exposure, particularly for those of us in the US who are at significantly less risk than people living in Japan. So while it is not useful to say, “hey you! Stop being afraid!,” I will strongly recommend that folks do what they feel they must to control their anxiety. Staying abreast of current events sometimes helps and sometimes does not help, since so many news articles are written to be eye-catching, and few things catch the eye faster than exaggerated claims and sensationalism. I would recommend finding one or two news sources that you trust and only monitor those. Do be sure to avoid any news sources with overly sensationalizing headlines or flashy pictures of trauma and devastation. Some of the news sources from outside the US may actually be more accurate and less sensationalizing than many mainstream news sources here in the US.

In summary, I recommend that we all put our panic into perspective, increase our intake of fresh fruits, vegetables and seaweed, and continue to monitor reliable media sources for further information. If you do have potassium iodide on hand, DO NOT TAKE IT unless you have seen a reliable source of information telling you that levels of radioactive Iodine-131 in your area have become high enough to pose a health risk (over 100 mSv for adults). I would recommend waiting until a public health agency declares such a thing, but I understand not everyone believes that our government is monitoring carefully enough. If you are of that mindset, please at least wait until the sources you trust show a significant elevation in Iodine-131 in your environment before taking high doses of potassium iodide. 130 mg of potassium iodide is not a prophylactic dose, and is not a safe dose of iodine to take on an ongoing basis.

Some links:
What is radiation? from the EPA
FAQ from the Union of Concerned Scientists
FDA FAQ for bioterrorism and emergency preparedness
Explanation (with visuals) of relative radiation risks in Tokyo
Explanation of risk from radiation exposure
Links to studies of specific foods for protecting against radiation damage

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