The public hearings on The Nature of Radioactive Fallout and Its Effects on Man had their origin in studies initiated over a year ago -- in July 1956 -- by the staff of the Joint Committee on the general subject of long-term radiation hazards, both from the military and peacetime atomic energy program. During the summer recess, following the conclusion of the 84th Congress, the staff assembled background materials on fallout, with primary emphasis on the research aspects. Following official announcement of the hearings in March of this year a detailed technical outline describing the proposed scope and subject matter of the hearings was prepared by the staff. On April 18, 1957, a Special Subcommittee on Radiation under the chairmanship of Representative Chet Holifield of California was established to conduct the hearings and to look into radiation problems in general. The hearings, which were all open to the public, were held on May 27-29 and June 3-7, and covered the major aspects of the fallout problem from its inception in nuclear weapons explosions to its effects on man. In all, some 50 witnesses either appeared personally before the committee or submitted statements for the record. The staff has prepared a summary analysis of the hearings which is aimed at pointing up the more significant information which emerged from the hearings. This analysis does not cover all points that were discussed in the hearings. An effort was made to describe the general areas of agreement which developed and to delineate those areas in which unresolved questions still exist. - Foreword.