Just when we thought the Japanese nuclear disaster could get no worse, they announce the radioactive contamination of produce, milk and water. Is it not bad enough already?
There has indeed been some low level radioactive contamination of locally produced food, milk and water in Japan. The major radioactive isotopes involved are identified as Iodine 131 (I 131) and Caesium 137 (C 137).
First, how could such a thing happen? There has been persistent, low-level leakage of the products of nuclear fission since the disaster started. This could be from emergency venting of the reactors to avoid rupture or due to fire involving waste fuel rods. Conceivably, there might even be damage to the reactors. These are heavy elements, and they are unlikely to go very far from the nuclear plant.
Unlike Chernobyl, the amount of release has been quite small, and there have not been any raging fires to blow these things up into the stratosphere. Nevertheless, we have a bit of measurable radiation in water, spinach and milk very close to the plant.
I-131 is the better known of the two radionucletides. It is a radioactive form of the element iodine. We buy iodinated salt to get the small amount of iodine we need to make thyroid hormone. Making thyroid hormone is basically the only use your body has for iodine. If there is I-131 in the environment, and you happen to eat food contaminated with it, it will head straight to the thyroid gland (the body thinks it is normal iodine). While the thyroid gland is busy making thyroid hormone out of it, it is quietly irradiating your thyroid. This can cause some genetic damage, and many years later it is possible this could lead to thyroid cancer. For the record: thyroid cancer is one of the most curable cancers out there.
The problem with I-131 is what doctors call “self limiting.” The half life of I-131 is only 8 days. That means 50% remains 8 days from now and 25% 16 days from now. By 5 half lives (40 days), the stuff is practically gone.
No discussion of I-131 is complete without discussing KI (potassium iodide) – the wonder pill. For all you hear about this stuff, it should be $100 a pill and a government secret. Alas, it’s just an easily-made type of iodine. If you are on supplemental iodine, the thyroid will be filled up and won’t hold on to any I-131 it comes across, which is helpful only when you are around I-131 (which we’re not).
Caesium 137 is another radioactive isotope that is in the area of the reactors. This is a much more troublesome substance. If being radioactive is not enough, it is also chemically poisonous, water soluble and tends to settle in bones. C137 has a half life of 30 years, so it takes 150 years (5 half lives) for the radiation to be manageable. No one is allowed near Chernobyl because of still highly radioactive Caesium 137 in the soil.
If C-137 gets into your body, the biologic half life is 70 days, rather than 30 years. So you will be effectively rid of it in just about one year (350 days). That’s at least one year too long for most people.
Food can get contaminated by radioactive dust falling on spinach leaves. Radioactive dust can contaminate grass and be eaten by dairy cows, producing radioactive milk. Now before we give ourselves osteoporosis from avoiding milk and anemia from avoiding spinach, we need too remember two things: 1) the damaged reactors are in Japan, not California, and 2) the radioactive contamination is so minor, there is no danger.
How much milk from next to the Japanese reactor do you think gets exported to the United States? Zero. Same goes for spinach. These are locally grown products that are consumed locally, and not even there these days. Even if the radiation was not in question, it would cost a ridiculous amount to fly milk and spinach around the world.
But you can bet that you are protected by more than just distance and the law of supply and demand. Export of Japanese agricultural products, few that they are, are carefully inspected for the least trace of radiation before being accepted in this country.
Radiation identified in the food chain is certainly dramatic news. It was a predictable and expected consequence of the Japanese nuclear reactor trouble. Thankfully, we are safely on the opposite side of the planet.