Japan, Radioactive Fallout and Iodine Questions

Many people are rushing to buy potassium iodide tablets in response to the radiation release in Japan.  Here are the facts:

Iodine-131 is one of several radioactive elements that may be released into the atmosphere when nuclear reactors break down.  It is targeted for attention due to it’s ability to disrupt thyroid function. Iodine-131 has a “half life” of just over 8 days, meaning that 50% is broken down in the first 8 days, and about 12.5% of the radioactive element is present after 24 days.  The iodine-131 may be carried by wind, settle out hundreds and even thousands of miles away and contaminate feed, cow’s milk and other agricultural products. It is also absorbed through the lungs by respiration.

Once absorbed, iodine-131 is deposited in the thyroid gland, which produces hormones used to regulate almost all body functions.  The radioactive decay particles can damage the thyroid, leading to increased risk of thyroid cancer and hypothyroidism.

How does the disaster in Japan affect those in the US?
When Iodine-131 is released, it spreads over an increasing area and is diluted.  It is carried by the wind and gradually  is distributed throughout the global atmosphere.  It may “fall out” and enter the lower atmosphere through storms or normal air circulation patterns.  Emissions from Japan could reach California in as little as 10 days, although the concentration would be very low.

How much iodine do we need to be safe?
Radioactive iodine-131 is absorbed along with normal iodine from your diet, to the point of ‘saturation”.  We can protect ourselves by insuring that our iodine levels are adequate.  According to the USDA, the RDA of iodine is 150 micrograms per day (220 micrograms during pregnancy, and 290 micrograms during lactation) and we receive an average of 270 micrograms per day from food, depending on our diet and location.  The USDA Tolerable Upper Intake Level for adults is 1.1 milligrams per day.  An adult thyroid may contain about 15 mg of iodine when saturated.  Excess iodine is removed from the body through the kidneys.

Iodine absorption is inhibited by soy products, and to a lesser extent by cassava and cruciferous vegetables (cabbage, Brussels sprouts, kale, etc.), all of which play a role in a health conscious diet.  Given the average daily intake, body need and reduced absorption, it is likely that many Americans, and most pregnant and lactating women are iodine deficient.  The greatest risk may be those who try to follow a healthy diet!

Potassium iodide pills that are distributed for emergency treatment and 130 mg, containing 100 mg of iodide per tablet.  They are taken daily only as long as there is high risk. They are not used long term due to fears of iodine overload, which can cause the thyroid to shut down.  Even with full meltdown in Japan, the concentration of radioactive iodine reaching the US would not warrant use of this massive dose.

Many scientists believe the upper tolerable intake level of 1.1 milligrams per day is inadequate, and point out that the average iodine intake in Japan is 50-80 milligrams per day, with no adverse effects.  Some health researchers support taking up to 50 milligrams of iodide per day.  My research can neither prove or disprove the safety of this level of supplementation.

The Bottom Line:  What to Take
Given the current situation, I recommend everyone consider increasing their intake of iodine to the Upper Tolerable Intake Level to insure that body needs and reserves are met.  These limits are:
1-3 years        200 mcg/day
4-8 years        300 mcg/day
9-13 years     600 mcg/day
14-18 years   900 mcg/day
19+  years    1100 mcg/day

Kelp is an excellent source of iodine, typically containing 400 micrograms per capsule (Nature’s Way brand).  Adults should consider 3 capsules per day, teens 2 capsules per day, and children 1 capsule per day.  Supplemental iodine is not appropriate for infants.

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