HEALTHNET

Antidote for radiation?

An earthquake has not only destroyed the homes of the Janpanese, it also raised public concern about the safety of nuclear energy. Ever since the nuclear accident in Fukushima, countless suggestions have been made protect oneself from the hazardous and notorious impacts due to radiation exposure. Iodine pill, perhaps, is the most common belief. However, can we shield ourselves from radiation by trying any of these iodinated substances?

What is iodine?
Iodine(I) is an essential raw material for the synthesis of thyroxine in our bodies. After taking iodine-rich food such as seaweed and kelp, iodine will be absorbed and stored in our thyroid glands for future use. Potassium iodide (KI), the active ingredient in the iodine pill, can be used for the treatment of thyroid storm and as a preventive measure for adverse effects related to certain operations. In addition , potassium iodide is sometimes added into salt so as to ensure that there is sufficient daily intake of iodine.

A preventive measure after nuclear accidents?
After nuclear accidents, radioactive substances, in particular radioactive iodine, are released to the environment contaminating the soil and the air. When the radioactive iodine enters the bodies, it will be stored and concentrated in the thyroid gland, similar to the dietary iodine. Radioactive iodine, however, can cause damage and mutation in thyroid cells, leading to hypothyroidism or even thyroid cancer in the long run. Iodine pills will remind the body that there is enough iodine stored in the thyroid gland. Therefore, it can prevent the uptake of radioactive iodine and thus protect the thyroids. Nevertheless, potassium iodide can only prevent the damage caused by radioactive iodine but not other radioactive substances.

All iodinated substances offer protection?
Since some kinds of food and salt contain potassium iodide, does that mean an increase intake of these foods can protect the thyroid gland against damage? WHO recommends 20-40mg of iodine to be added to each kilogram of table salt. Each iodine pill contains 100mg of iodine. In other words, one needs to consume at least 2.5kg of salt (approximately the weight of a notebook computer) in order to acquire a therapeutic amount of iodine. Therefore, one cannot rely on food intake to protect oneself from the harmful effects of the radioactive iodine. External iodine preparation (e.g. Povidone-Iodine solution) is only used as an antiseptic. Its iodine content cannot be absorbed into the body and therefore cannot protect against radiation.

In fact, the appropriate dose of potassium iodide depends on a number of factors such as the age and the extent of radiation exposure and is adjusted accordingly. General public is advised to carefully evaluate information available. Following rumours may lead to a waste of money or even cause damage to one's health.

Source: Drug Education Resource Centre, The Society of Hospital Pharmacists of Hong Kong