As the post tsunami drama in Japan unfolds, we thought it would be helpful to place the radiation exposure risk posed by the Fukushima nuclear power plant damage into perspective. Radiation surrounds us all the time. At what point do levels become dangerous?
The World Nuclear Association, made up of top nuclear specialists, has produced a guide that may help calm the pervasive hysteria that has swept the world over the past few days. There are many different types of radiation, the most dangerous type is ionizing radiation measured in sieverts. Because sieverts are so big, radiation levels are usually provided in millisieverts, mSv, or one thousandth of a sievert.
We are exposed to radiation every time we have a head CT scan (2.0 mSv) or chest X ray (0.1 mSv). Every year our annual exposure from natural radiation is 2.0 mSv. By comparison, a single dose of 10,000 mSv is required to cause fatal radiation sickness; 1000 mSv to cause non-fatal, temporary radiation sickness (nausea, vomiting, low white blood cell count), and an accumulated dosage of 1000mSv to cause a statistically significant increased risk of cancer.
So how high are the levels in Japan? At its peak (thus far), the radiation level of 400 mSv per hour was recorded at the Fukushima nuclear power plant on March 14 (the levels have dropped significantly since then).
Several dozen Japanese workers, who may have been exposed to the highest levels of radiation at the Fukushima nuclear power plant, were given potassium iodide as a precautionary measure to mitigate the increased risk of thyroid cancer. Several hundred children and young adults exposed to very high radiation levels in the aftermath of the Chernobyl nuclear disaster developed thyroid malignancies. No potassium iodide was available to them at the time of exposure.
HTH has received inquiries from its clients in Japan about taking potassium iodide. The answer is clearly “no”. According to Dr. Joe McLaughlin, the Alaskan state epidemiologist, “While potassium iodide can protect the thyroid gland from harmful radiation, it can produce adverse side effects and should only be taken if exposure to considerably elevated doses of radiation is expected to occur.”
It is unfortunate that the risk of significant radiation injury from the damaged nuclear cells in Fukushima has taken center stage in Japan. Devastation from the earthquake and the tsunami that followed is mind boggling, to say the least. Helping the Japanese people recover and put their lives back together must remain the world’s priority, not speculating about a nuclear threat.
Photo by DigitalGlobe-Imagery