Answer to Question #10856 Submitted to "Ask the Experts"

Category: Nuclear Power, Devices, and Accidents — Nuclear Power

The following question was answered by an expert in the appropriate field:


Question: We are writing this inquiry to see if we can get some scientific answers concerning the screening for any possible radioactive contamination in pharmaceuticals imported from Japan.

During the last four years we have been using a tubed eczema medication called "protopic ointment" that is made in Japan, not so far from the Fukushima disaster area. What is very concerning is that the black-box warning information that came with the last prescription said that it is made in Japan and it is made from the soil bacterium. It is made in a province called Toyama and we also read in an article that this province is monitored for possible radiation contamination.

We have tried to get answers about the chain of supply of this product and find out just how it is screened at the point of export and at the point of import in the United States before it is distributed. We understand that it is a huge job to monitor all imports and information has been quite vague and not definitive. The gentleman at the Food and Drug Administration recommended we inquire with scientific resources for some of our specific questions about the radiation issues so we are writing to the Health Physics Society. The company that sells the product did not get back with a response after several calls as well. Information that has a monetary interest involved is not as assuring anyway.
We understand that there are different kinds of radioactive contamination and they have different half-lives. What types of specific radiation resulted in the environment after the disaster in this area? Is there a possibility that any exported products like this could have any problem? If there was any contamination of any pharmaceutical products, what type of contamination would it most likely be and what would be its likely half-life? The reason we ask, is that these prescriptions last a long time (several months), and we always stored them in our medicine storage area with other pills and drugs we take. Now being aware of where they are made and what they are made from makes us concerned in case there would be any chance of contamination. If there was any possibility, how long would there likely be a concern to anything kept in the same area?
Having explained all this, we have some specific inquiries as to how we can best test our own medication and the storage area just to be sure. We have done some research on consumer radiation testing devices that can be used in the home, but it appears that certain devices measure only certain types of radiation. What specific types of radiation measurements would a device used for this have to include? Are there any hand-held or smaller-type instruments that would be effective?


Toyama prefecture in Japan lies on the opposite coast from Fukushima. I believe it is about 320 km from Fukushima. Given its location, I would not expect it to have been subject to very significant radioactive contamination from the Fukushima accident. The radionuclides that were released in greatest amounts were radioisotopes of iodine, especially 131I, and two isotopes of cesium, 134Cs and 137Cs. The iodine isotopes have short half-lives and have mostly decayed away. The 134Cs has a half-life of about two years and that for 137Cs is about 30 years—so these radionuclides would still remain in the environment to which they were released. Any 137Cs present will persist for many years, its amount being reduced by a factor of two every 30 years. Both of the cesium isotopes decay with the emission of beta radiation (electrons) plus gamma radiation.

I do not know a great deal about soil bacteria, but from what I have read I believe that the ointment you describe likely uses an active ingredient called tacrolimus, a compound that suppresses the immune system and that is made by the bacterium streptomyces tsukabensis. Cesium falls in the alkali metal group and will follow potassium somewhat in its chemical/biochemical behavior. As such it is likely that many soil bacteria will take up some cesium, if it is present in the soil, as part of their normal metabolic processes. I have not found anything to indicate that this particular bacterium heavily concentrates cesium as do some others. It would be hard to predict how much, if any, radioactive cesium in the soil would end up in the compound ultimately prepared for use in your ointment. Given the low likelihood of any significant radioactive contamination in Toyama prefecture, I would not expect any significant contamination in the ointment that you describe.

The U.S. Food and Drug Administration does monitor all drugs imported from the 10 prefectures closest to Fukushima, Japan. I have not heard of any instances of drug contamination with radionuclides from Fukushima. I believe Toyama lies outside of the closest 10 prefectures so it would not be specifically monitored. The Japanese Ministry of Health, Labour, and Welfare has been doing monitoring of many products, especially foods and water since the accident. The results I have seen for Toyama prefecture have shown no evidence of any significant food contamination from the accident; this would support the notion that no significant soil contamination has accrued in Toyama.

If you still want to check on the ointment product yourself, I would recommend a portable thin-window Geiger-Mueller type detector. I prefer the type that has a sufficiently thin window to allow measurement of alpha, beta, and gamma radiation. Neither cesium isotope emits alpha radiation, but the thinner window enhances sensitivity to the beta radiation that the isotopes do emit. You can find more discussion of the use of such detectors on the Health Physics Society Ask the Experts website—see, for example, Question 9974 and Question 10792. In addition to measuring the ointment tube directly (which would primarily allow measurement of gamma radiation), I would recommend squeezing a small amount of the ointment onto a hard surface and spreading the ointment into a thin layer, perhaps one or two square inches in area. If there is any radioactive cesium in the ointment, the thin layer would allow for reduced radiation attenuation and consequently greater likelihood of seeing more beta radiation. Hold the window of the detector about 1 cm above the layer of ointment when measuring.

As I have said, I do not expect you will see anything but, if you do buy a detector, you will probably find it interesting to observe the radiation environment in which you live. Our world is bathed in naturally occurring radiation and there may be significant variations in background readings, depending on local conditions. Make sure you obtain a good reading of the radiation background before you attempt measurements on the ointment or any other materials of interest.

I hope you satisfy your concerns and that the product you are using is not a problem. Best wishes.

George Chabot, PhD

Answer posted on 20 November 2013. The information posted on this web page is intended as general reference information only. Specific facts and circumstances may affect the applicability of concepts, materials, and information described herein. The information provided is not a substitute for professional advice and should not be relied upon in the absence of such professional advice. To the best of our knowledge, answers are correct at the time they are posted. Be advised that over time, requirements could change, new data could be made available, and Internet links could change, affecting the correctness of the answers. Answers are the professional opinions of the expert responding to each question; they do not necessarily represent the position of the Health Physics Society.