Preface: This is written for the millions of people around the world who are worried about radiation from the Japanese nuclear reactors. For those who are not worried about radiation from Japan, you can ignore this post, or save it for any future radiation scares closer to home.

How do we protect ourselves against radiation?

It is true that potassium iodide protects against high doses of a certain type of radiation. As the New York Times notes:

Fortunately, an easy form of protection is potassium iodide, a simple compound typically added to table salt to prevent goiter and a form of mental retardation caused by a dietary lack of iodine.

If ingested promptly after a nuclear accident, potassium iodide, in concentrated form, can help reduce the dose of radiation to the thyroid and thus the risk of cancer. In the United States, the Nuclear Regulatory Commission recommends that people living within a 10-mile emergency planning zone around a nuclear plant have access to potassium iodide tablets.

Indeed, virtually all suppliers of potassium iodide have sold out, especially after , the U.S. Surgeon General recommended that West Coast residents stock up.

But as I noted yesterday:

Keep in mind that iodide only protects against one particular radioactive element: radioactive iodine, technically known as iodine-131. Iodine-131 has a half life of only 8.02 days. That means that the iodine loses half of its radioactivity within 8 days.

The government hasn't stockpiled much potassium iodide. As the New York Times notes:

Congress passed legislation in 2002 requiring the federal government to supply potassium iodide capsules to people living within 20 miles of nuclear power plants in the United States.

But the administrations of George W. Bush and Barack Obama have not implemented that provision, saying the law allows for alternatives.

Some states have given pills to people living within 10 miles of nuclear plants, or stockpiled the pills for those people.

But given that the government says that only minute amounts of radiation will hit the United States, and given that iodine-131 has such a short half-life, the whole issue may be moot (many, however, do not trust the government's assurances. See this and this). And taking high doses of potassium iodide can be harmful, especially for people with certain pre-existing medical conditions. So talk to your doctor before taking any.

Other Radiation Dangers

While iodine-131 poisoning can be prevented with potassium iodide, there are no silver bullets for other radioactive isotopes.

As I pointed out yesterday:

The New York Times noted last week that - in addition to iodine-131, the big danger is cesium:

 

Over the long term, the big threat to human health is cesium-137, which has a half-life of 30 years.

At that rate of disintegration, John Emsley wrote in “Nature’s Building Blocks” (Oxford, 2001), “it takes over 200 years to reduce it to 1 percent of its former level.”

It is cesium-137 that still contaminates much of the land in Ukraine around the Chernobyl reactor.

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Cesium-137 mixes easily with water and is chemically similar to potassium. It thus mimics how potassium gets metabolized in the body and can enter through many foods, including milk.

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The Environmental Protection Agency says that ... once dispersed in the environment ... cesium-137 “is impossible to avoid.”

Cesium-137 is light enough to be carried by the wind a substantial distance.

There is no surefire prevention for cesium-137. As the EPA notes in a discussion entitled " What can I do to protect myself and my family from cesium-137?":

Cesium-137 that is dispersed in the environment, like that from atmospheric testing, is impossible to avoid.

Neither the EPA - nor any other government agency - gives advice on how to minimize the danger from cesium-137 poisoning. Some have theorized about

So does that mean that we're sitting ducks?

Well, the fact that there is no silver bullet (although some have theorized about potential approaches) does not mean that there is nothing we can do.