Radiation in the Mountains: Q & A
The following is a translation of an interview conducted with Katsumi Shozugawa, an Associate Professor and Researcher at The University of Tokyo Graduate School of Arts and Sciences, which appeared in the January 2012 issue of Yama-To-Keikoku Magazine, a monthly outdoor magazine published in Japanese. This translation has been done with the consent of the magazine and should be of interest to hikers in Japan who can’t read Japanese. The opinions expressed here reflect those of Mr. Shozugawa and not of Yama-to-Keikoku or Hiking in Japan.
Question 1: Aren’t the radiation levels in mountains streams high?
Recently we tested Karasugawa river (on Mt. Adatara) and found that above Karasugawa bridge radiation levels varied from 0.05 microsieverts/hour* to 0.312 microsierverts/hour. However, at the bridge level at the river embankment the readings were 0.184 and decreased to 0.176 at the surface of the river. From this we can see that because of wind and rain, soil or leaves containing radioactive cesium have been transported, the speed of which varies according to region. For this reason, over time the areas which have previously had a high air dose rate can fluctuate. In this way, due to the fact that environmental conditions are constantly changing, it’s difficult to accurately predict whether mountain streams have high or low levels of radiation.
Question 2: Are there any radiation hotspots in the mountains?
Yes there are. This time approximately 0.02 microsieverts/hour was observed on a forest road at the edge of a gully. We also measured at the base of the gully and found readings nearly double what was found at the forest road. When you take a rest during your hike, it’s best to avoid these types of gullies where mud and runoff have accumulated, as well as areas with large piles of rain-transported foliage.
Question 3: Is it ok to take home fallen leaves or soil from the mountains?
It has been reported in the news that fallen leaves have contained a high level of contamination, but if you want to take home one leaf as a memento, it shouldn’t be a problem. However, you should refrain from taking away large quantities of foliage as well as rustling through large piles of fallen leaves.
Question 4: Since the snow season has arrived, what kind of radioactive effect will there be?
Since snow will cover the land, you won’t need to worry about flying radioactive particles or the risk of internal radiation exposure. In addition, snow has a shielding effect against radiation, depending on the density of the snow. We can expect a 30 to 40% reduction in radioactive emissions in compacted snow (such as those in groomed ski resorts). If the snow has accumulated over 1 meter in depth, however, then it is thought there will be a full shielding effect. Since fresh snowfall has a low risk of contamination, it should not be a problem to drink snowmelt.
Question 5: Is it ok to gather and eat mushrooms from the mountains?
There hasn’t been adequate testing, so you should not eat wild mushrooms gathered in the forest. In the mountains, there is a high likelihood for radioactive contamination of kinoko mushrooms, chestnuts, freshwater fish, river crabs, wild boar and such. Since the mountainous landscape is extremely diverse, even small changes in location can result in varying levels of contamination. Viewing wild mushrooms is ok, but you should refrain from picking and eating them.
Question 6: What should you do if you fall and injure yourself, getting dirt into your open wound?
There is a danger that radioactive materials attached to soil could directly enter your bloodstream, which is thought to be more dangerous than direct inhalation or drinking contaminated water. In order to decrease internal radiation exposure, wounds should be washed with water as quickly as possible. After washing, the wound should be wrapped with a bandage in order to prevent dust and dirt from reentering the wound. It is safer to use a hydrocolloid dressing (such as a kizu power pad) to help keep air out.
Question 7: Is it safe to drink from the mountain streams and rivers?
Since radioactive cesium has a positive charge, it is easily bonded to clay particles containing a negative charge. Once this happens, it is thought that there is a low chance of these bound particles dissolving in water. This being the case, as long as Iodine 131 is not emitted, there shouldn’t be a worry of contamination of underground water sources. Since there is a danger of contamination in the dirt riverbeds, you should avoid ingesting dirt particles when drinking water from streams. Instead, water should be filtered with a portable water filter.
Question 8: Are there any precautions you should take after finishing your hike?
At the trailhead, please clean off all dirt that has stuck to hiking boots, clothing, and your backpack. When doing this, be sure not to inhale any of the brushed off dust. Since volcanic soil can contain especially strong acids and alkaline metals, you should wash off your boots immediately after finishing your hike. If you don’t, the rubber and leather can deteriorate rather quickly. Regardless of whether there is radioactive contamination or not, it’s my recommendation to promptly clean off everything before returning home.
*Read here for more information regarding measurements of radiation.
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Hiking in Japan 
April 9, 2012 at 8:39 am
Wow, I had no idea that radiation on mountains was an issue….is this radiation from the sun, or..?
April 9, 2012 at 5:29 pm
Unfortunately it’s radiation from the stricken nuclear power plant. Hotspots are definitely an issue, which is why I do not recommend hiking in Fukushima Prefecture. The mountain you really need to watch out for is Mt. Adatara, which is where most of the readings were taken. The measured doses of cesium are quite low, but I’d rather avoid ANY doses of radioactive cesium if i can. There is also a ski resort at Adatara that is still open for business in spite of the contamination.
April 10, 2012 at 12:52 pm
Ahhhhh, I see, I see. I was worried for a minute that this was in regard to all mountains~~
But even if that’s not the case, it’s still a bit frightening for the people in the area. :(
May 10, 2012 at 2:18 am
Wes: many thanks for posting this article – your excellent translation is a public service and it’s good to see YamaKei tackling this difficult subject in a responsible, factual and non-sensational way. Even so, I still find it difficult to assess (from this interview plus the linked fact sheet) whether or not these levels of radiation are something to worry about or not. That is, after all, the Yen 100 million question….
If I may, I will forthwith link to this thought-provoking page from my own posting on the caesium fallout.
May 27, 2013 at 12:59 pm
These levels are extremely low. To give some perspective, when you get an abdominal CT scan its about 7milliSieverts in one hit (ie over 10,000x these levels!) So you could spend two entire years exposed to 0.312uSv/h and still be under what you’d get from a CT scan.
July 31, 2013 at 1:14 am
The level you refer to is low, but constant, unlike a CT scan that lasts for a very short time, and still does some damage. The environmental contamination is constantly bombarding your body from the outside. Additionally, and this is key, you are certain to get internal exposure via ingestion or inhalation. Those internal contaminants stay in your body and your dose rate from that moment on will be constant and focused on the tissue in the immediate vicinity. That is where you WILL have cancer. There are other affects from these contaminants, not just radiation induced. Even without the radiation, these isotopes are poison and damage the function of tour organs, bones, mucles, neral networks and hormonal systems. It is a huge mistake to be anywhere near Fukushima (100’s of kilomiters away). Please heed the warning, it is real.
May 21, 2012 at 6:35 pm
Wes – nice job on the translation.
A general comment not aimed at your good self: My layman’s perspective on this subject is that these figures are still low and should not cause great concern. The below link gives some interesting information that also helps to clarify any perceived danger. It’s worth noting the difference between ALARA and AHARS figures. I think every press article I’ve read so far always refers to the ALARA figure as though it’s a safety limit, when it’s not. As PH says above, the real question is are the levels mentioned in your translation something to worry about and section 6 hopefully helps to answer that question. http://www.publications.parliament.uk/pa/cm201012/cmselect/cmsctech/writev/risk/m04.htm
I noticed this morning that the Daily Yomiuri has recently been reporting in this area too: http://www.yomiuri.co.jp/dy/national/T120518004537.htm
November 21, 2013 at 10:45 am
Great website! Thanks for the wonderful info that helps hikers meander their way through the peaks and woods of Japan. Also, thanks for taking the radiation issue seriously. It is quite challenging for the common person to understand the dangers the fallout from Fukushima Daichi poses.
My purpose in posting is to alert readers that there has been an active public relations campaign to downplay realities, misinform with bogus statistics and to slander those who question the standard narrative. Just about every website in Japan which offers information about Fukushima and a comment section has been onslaught by this propaganda campaign. Hopefully, investigative reporting will trace the sources (follow the ¥) of this campaign. Are those posting here just concerned people with a viewpoint or sneaky propagandist pushing an agenda? That is difficult to know but there are patterns that can be analyzed. The Counterpunch article is to alert readers to the background of the man who is referenced as an “expert” source in the above post.
http://www.counterpunch.org/2011/03/28/deconstructing-nuclear-experts/
I don’t have the answers, but I would warn people to be cautious and skeptical. Fukushima quickly was given the worst designation for a nuclear accident by the establishment itself. To claim that this has had and is having no effect, when basic science shows that all radiation exposure even at the lowest level, increases risk of cell mutation, is pure hogwash. To further the point, what has been and what is leaking from Fukushima is not naturally occurring forms of radiation exposure. However, if you are inclined to believe Strontium radiation settling in your bones as it mimics calcium is the same as eating a banana, getting a sun tan or flying in an airplane, then more power to you as wander through life.
Happy hiking! Let’s fight to keep our world safe and clean.
November 21, 2013 at 6:31 pm
Amishukuf – Some info for you on Chris Busby, the author of the link you posted above:
http://www.theguardian.com/environment/georgemonbiot/2011/nov/22/christopher-busby-nuclear-green-party
http://en.wikipedia.org/wiki/Christopher_Busby
Happy hiking!