(I) In 1954, a hydrogen bomb was tested on the Island of Bikini. (II) The explosion produced the expected radio-active fall-out on a number of Pacific islands, and also scattered debris over thousands of square miles of sea. (Ill) As a result, dangerous radioactive materials appeared on the surface of the sea and finally infected the tuna fish which are an Important article of diet in Japan. (IV) This is riot the only large sea to have been polluted. (V) It is hardly surprising, then, that a number of Japanese ingested quantities of radioactive food.