Sex, Drugs, and Public Health

March 24, 2011

Radiation and Public Health

Filed under: Uncategorized — cbmosher @ 4:48 am

Public Health authorities have been bombarded with questions about radiation. Like many things in our lives, radiation can be both good and bad for us. Depends on how much and what type.

Last Week, many people in the United States became concerned – some became panicky – about a new kind of air pollution: radiation from Japan’s nuclear reactor accidents. At the Health Department, we received several phone calls asking about the threat. The press, we noticed, focused on the topic to an extraordinary degree.

Most of the radiation in our daily lives comes from the sun (which is, after all, a gigantic nuclear explosion in the sky). It warms us when we are cold, it helps our food grow, and it creates Vitamin D in our bodies. But it can also burn us or, if we are foolish, it can blind us. You could think of these ill effects as overdoses of radiation.

Another source of radiation in our lives is medical radiation. Chest x-rays, various types of scans, and cancer treatment radiation are all thought of as beneficial. Radiation affects different tissues in the body in different ways. Generally, tissue which multiplies quickly is more susceptible (e.g. skin and intestines). One specific use in medicine involves the thyroid gland.

Sometimes we give a patient radioactive iodine in low doses to get a better look at the thyroid – to find cancer hidden within it, for instance. The thyroid gobbles up iodine readily and a scan with radioactive iodine can give us a picture of the gland we otherwise can not get.

In those patients with overactive thyroid glands, a way to “remove” the gland without surgery is to give a high dose of radioactive iodine, which will destroy (“ablate” in medical terms) the gland. All these uses are beneficial.

But the ingestion of radioactive iodine which is a by-product of a nuclear reactor leak can be dangerous to a certain group: young people who live close to the reactor. Studies after the Chernobyl accident showed that people who were children at the time of the accident had an increased likelihood of cancer from exposure to radioactive iodine (a certain number of cases of thyroid cancer would occur even without exposure to a nuclear accident, so we measure “excess incidence” of the cancer.)

The reason nuclear regulatory agencies provide potassium iodide to residents close to a reactor in case of a leak, is to make their thyroid glands get “saturated” with iodine, thus rejecting radioactive iodine. It’s a little like you, after a big Thanksgiving Day meal, might reject an ice cream sundae. Thus the potassium iodide can protect against excess cancer of the thyroid caused by “radioactive iodine” among people young enough and close enough to be at risk.

Is there a danger in taking potassium iodine? Sure, it is a drug. Thus some of the concerned Americans who, 6000 miles away (about 5950 miles beyond the “danger zone” where potassium iodide might be used) who took it on their own, ended up in the emergency room with allergic reactions or a potassium overdose, which could be lethal.

So the best approach is to allow the Air Pollution and Public Health folks to continue their monitoring to determine whether any excess radiation has appeared from Japan, over and above our “natural background” levels of radiation.

So far, that is not been the case.

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