New research revises the conventional wisdom about potassium iodide?

A recent article in Archives of Internal Medicine would seem to have some serious implications for the long-held wisdom about using potassium iodide to protect humans against accidental releases of the radioactive isotopes of iodine. The findings suggest that this prophylactic treatment is itself likely to cause almost as much damage as it is supposed to prevent.

The research was not concerned at all with nuclear accidents. It focused instead on the use of iodide contrasts used in some medical imaging tests. A New York Times report on the research paper states that worldwide, annually, 80 million iodide contrast doses are administered for CT scans. The typical dose of the contrast agent contains between 90 and hundreds of times the daily dose that people get through a normal diet. The researchers found that among people who developed thyroid diseases over a 20-year period, they were 2 to 3 times more likely than others to have had an iodide contrast agent administered in the past.

The relevance to the nuclear energy debate seems obvious to me, but the authors of both reports mentioned here don’t make the connection. They are more concerned with the millions of CT scans that are being done, many of them non-essential, considering the trade-off presented by these new-found risks.

In the nuclear accidents that happened in Chernobyl and Fukushima, local residents were exposed to doses of radioactive iodine far above the typical dietary intake of stable iodine. Because radioactive iodine behaves chemically in the same way as stable iodine, a large dose of it would have the same effect as the large dose of iodide given for CT scans. This would be in addition to the harmful effects caused by radioactive decay of these isotopes.

The negative health impact would also occur even if the population received potassium iodide in a timely manner. The doses given are, like those given for CT scans, hundreds of times the daily dietary intake, so these too would have the negative impact of iodide given for CT scans. I suspect this downside was known long ago because in history’s two big nuclear accidents, authorities hesitated to distribute potassium iodide. Once they had data on releases and wind direction, they had to make decisions, knowing that what might be seen later as an over-reaction would cause many future cases of thyroid dysfunction. The new research shows that there is some wisdom in delaying, in telling people not to take potassium iodide unless they know it is absolutely necessary, but this knowledge of the effects of massive doses of iodine, stable or radioactive, is a severe blow to the nuclear industry that has always said that potassium iodide was a sure way to protect people during an nuclear emergency. Obviously, it is has its downside.

The victims and liquidators of the Chernobyl disaster have always claimed that they suffered severely from non-cancerous diseases of the thyroid, but for decades their governments and the United Nations have denied that metabolic diseases are related to the disaster. This new research on the effects of high doses of iodide contrast indicate that it is time to admit that exposure to large amounts of any isotope of iodine involves serious risk to future health.

Hyperthyroidism can cause:

Hypothyroidism can cause:

Difficulty concentrating Fatigue Frequent bowel movements Goiter (visibly enlarged thyroid gland) or thyroid nodules Heat intolerance Increased appetite Increased sweating Irregular menstrual periods in women Nervousness Restlessness Weight loss (rarely, weight gain) Other symptoms that can occur with this disease: Breast development in men Clammy skin Diarrhea Hair loss Hand tremor Weakness High blood pressure Itching - overall Lack of menstrual periods in women Nausea and vomiting Pounding, rapid, or irregular pulse Protruding eyes (exophthalmos) Rapid, forceful, or irregular heartbeat (palpitations) Skin blushing or flushing Sleeping difficulty

Being more sensitive to cold Constipation Depression Fatigue or feeling slowed down Heavier menstrual periods Joint or muscle pain Paleness or dry skin Thin, brittle hair or fingernails Weakness Weight gain (unintentional) Late symptoms, if left untreated: Decreased taste and smell Hoarseness Puffy face, hands, and feet Slow speech Thickening of the skin Thinning of eyebrows

Sources:

Connie M. Rhee, MD; Ishir Bhan, MD, MPH; Erik K. Alexander, MD; Steven M. Brunelli, MD, MSCE. “Association Between Iodinated Contrast Media Exposure and Incident Hyperthyroidism and Hypothyroidism.” Archives of Internal Medicine. 2012;172(2):153-159. http://archinte.ama-assn.org/cgi/content/short/172/2/153

doi:10.1001/archinternmed.2011.677

O’Connor, Anahad. “Iodide Heart Scans Linked to Thyroid Disease.” The New York Times. January 23, 2012. http://well.blogs.nytimes.com/2012/01/23/iodide-heart-scans-linked-to-thyroid-disease/