結 論


 環境の特定のコンパートメントにおける、放射性核種と放射線エネルギーの量と流れに対する人間に起因する貢献の度合いは、自然界の貢献度合いと比較すると小さいものである。世界の一部の地域では、人間および他の生物への自然界の放射線量は、現在一般の人々へ容認されている線量限度よりも何百倍も高い。そのような地域において、人間、動物、植物への健康上の悪影響は見つかっていない。現在抽象的なLNTを根拠としている放射線防護の体系を将来再構築する場合には、自然放射線の高い地域における明らかに安全な慢性被ばくを考慮に入れた現実的なアプローチが必要である。したがって、この地域に関する研究は今後特別な関心と支援が必要であろう。

 20世紀には、人工的な電離放射線や放射能の幕開けが始まった。広島、長崎では人間の最善の知識を殺人に使用し、チェルノブイリでは最大規模の原子力事故を経験した。この事故では、30人の職業従事者が死の犠牲になっただけで、おそらく甲状腺障害の患者には死亡者はなく、原子力は発電のための比較的安全な手段を提供するものであることが結局はっきりした。相当高い亜急性放射線量によってがんを治療することができ、少量の慢性放射線被ばくは健康に有益であることも分かってきた。無制限なエネルギー資源への扉を開く"新しい"放射線や放射能の発見が、約50万年以前に火を発見したことに匹敵するほどの意味を人間に与えてくれている。我々の祖先は、ときには火を神聖視しつつ、何千年という長い時間をかけて火になじんできた。同じように、電離放射線や放射能に人間がなじむには、1世紀では短すぎたようだ。しかし、希望はある。現在は、すべてのことが以前にも増して、速くなってきているようだから。

 

謝辞 貴重な議論のご協力をいただいた、S. Chwaszozewski教授、L.dobrzynski教授、A. Strupczewski博士、および、M. Waligorski博士に感謝いたします。

 

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