Key historical study findings questioned in debate over threshold versus linear non-threshold for cancer risk assessment.

This paper demonstrates that the dissertation research of Ray-Chaudhuri (1939, 1944) that was used by Hermann Muller to support his radiation induced gene mutation hypothesis and linear non-threshold (LNT) dose response model during his Nobel Prize Lecture is "uninterpretable" with respect to these issues. The research failed to include essential research design information, resulting in reporting flaws that have never been previously identified. These observations are historically important because this dissertation was used to blunt powerful criticism of Muller's gene mutation research and strongly promoted his advocacy of the LNT model in radiation risk assessment.