The mission of the Committees on The Biological Effects of Atomic Radiation (BEAR) was to provide a thorough review of all that was known at the time about the effects of atomic radiation on living organisms. The Committees on BEAR had been put together in 1955 by then-NAS president Detlev Bronk in response to the increasing but uncoordinated accumulation of data on the effects of atomic radiation.
Six committees were formed to investigate various problems arising from the release or presence of radiation in the environment. These committees were: Pathologic Effects of Atomic Radiation (with various subcommittees); Meteorological Aspects of the Effects of Atomic Radiation; Effects of Atomic Radiation on Agriculture and Food Supplies; Disposal and Dispersal of Radioactive Wastes; and Oceanography and Fisheries. A number of reports, including two summary reports, the first released in 1956 and second released in 1960, were published by the various BEAR committees and subcommittees before the study was terminated in 1964.
The key conclusions of the BEAR I report that changed the dose-response default status from threshold to linear at low dose are embodied in the following two quotes on:
"Any radiation dose, however small, can induce some mutations. There is no minimum amount of radiation dose which might be exceeded before any harmful mutations occur."
"...if we increase the radiation that reaches there productive glands by X percent, the number of mutations caused by radiation will also be increased by X percent."
Key Historical Studies Serving as the Basis for the Linear Dose Response Challenged