拝啓 トーマス・ブレーク・グラバー様
セシウムなどが放つ放射線を浴びることを「被ばく」といいます。福島では、研究者が被ばくの影響と分析する「異常」が発表されてきました。
・野生サルの白血球や赤血球が減った
・幹が真っすぐ伸びないモミの木が増えた
・チョウ「ヤマトシジミ」の羽が小さくなった
これはあくまで一部です。個体数の減少と関連付ける発表もあり、栃木県北部では「オオタカの繁殖成功率が下がった」と報告されました。
原発に近い福島県飯舘村のため池では、２０１３年に捕ったコイの白血球が明らかに少なく、体内組織の崩壊も進んでいました。１４年になってからは栃木県東部の池のコイでも同様の傾向が認められ始めました。調査した東京大の鈴木譲（すずきゆずる）名誉教授（魚類免疫学）は「さらに多角的な検証は必要だが、栃木のコイでは初期被ばくの影響が３年後に現れた可能性も否定できない」と指摘します。
福島では住民の避難や耕作放棄地の拡大など、劇的に環境が変わりました。現段階では本当に「異常」が被ばくの影響かどうかは分かりません。被ばく総線量が十分に検討されていないとして、研究に疑問を呈する専門家がいるのも事実です。
被ばくの影響の度合い「放射線感受性」は種によって大幅に異なります。感受性が最も高い（放射線に弱い）のはヒトを含む哺（ほ）乳類。フクロウなどの鳥類やマスといった魚類、両生類も感受性が高いことが分かっています。植物ではモミやスギなど針葉樹が高く、チェルノブイリ事故では周辺の針葉樹林が高線量で枯死しましたが、広葉樹のシラカバは生き残りました。
チェルノブイリや福島よりもさらに低線量の奥日光では、被ばくの影響とされる現象は報告されていません。いや。そもそも調査がほとんど行われていないとお伝えしなければならないのです。
哺乳類は繁殖行動に被ばくの影響が出やすいといわれます。奥日光には国の特別天然記念物ニホンカモシカや天然記念物ニホンヤマネをはじめ、本州を代表する哺乳類がほぼ全て生息しています。彼らに何も影響がなければよいのですが…。
被ばくの影響は、次世代以降の子孫に現れることもあることが分かっています。あの日から、私たちの心配の種は尽きることがありません。
Dear Thomas Blake Glover
Exposure means to be exposed by radioactive materials such as cesium. In Fukushima, some scientists have published studies about some 'abnormities' that they analyse as an effect of the exposure. For instance;
-Decreases in white blood cells and red blood cells of wild monkey.
-Increases in fir trees whose trunk doesn't glow straight.
-Smaller wings of butterfly called pale grass blue.
These are only some of them. There are studies that associate with the decreasing number of individuals, such as northern goshawk which has been reported decreased success rate of breeding.
In 2013, in Iidate town near the Fukushima Daiichi nuclear power plant, carp of the storage reservoir had been found with decreases in white blood cells and increases in breakdown of body tissue. It was in 2014, when the carp of eastern part of Tochigi prefecture started to show the same tendency. Suzuki Yuzuru, the honorary professor of Tokyo University who investigated on the carp points out 'we cannot deny the possibility that it took 3 years for carp in Tochigi prefecture before the signs of initial exposure appeared, although a lot more research is needed from various perspectives'.
As a result of the nuclear accident, there has been a drastic environmental change in Fukushima prefecture by the evacuation of residence and the expansion of deserted cultivated land. We are not sure, at least for the time being, if those abnormities are really caused by the exposure. Some scientists are skeptical about those studies because of the insufficient estimation of the entire dose level.
There is a huge difference in radiation sensitivities?the susceptibility of the radiation effect--between species. Mammals including human are the most susceptible to radiation. Also, birds such as owls, fish such as trout, and Amphibia are also known to be highly susceptible. For plants, those needle leaf trees such as fir and cedar are more susceptible than others. The needle trees near the Chernobyl meltdown site stood dead from the high dose level, while the broad leaf trees such as birch survived.
In Oku Nikko where the dose level is much lower than that of Chernobyl or Fukushima, no symptom of radiation effect has been reported. To be more precise, I have to say, almost no research has been conducted yet.
Mammals are considered to be susceptible in breeding behaviors. In Oku Nikko, there exist almost all kinds of mammals that represent Honshu island of Japan, such as Japanese serow, designated as the National Special Natural Monument, and Japanese dormouse, the Natural Monument. I just hope that they will be safe and sound.
We know that radiation effect might appear in our children of the next generation. Our concerns have been nagging around ever since the day of the accident.
