Hermann Muller and his LNT scientific and policy leadership: Private communication reveals uncertainties.

The present paper highlights numerous publications of Hermann J. Muller with a focus on his opinions concerning the validity of the linear no-threshold dose response model for hereditary and cancer risk assessment. These comments reflect a very consistent and powerfully supporting position for the LNT model. However, newly discovered correspondence between Muller and Robley D. Evans reveals that Muller was highly uncertain about the supportive science, and therefore hid his real opinions, deliberately misleading the scientific community and governmental agencies. Of further historical value is that in the correspondence with Evans, Muller proposed what might be the first articulation of an environmentally based Precautionary Principle. These perspectives have remained unknown since Muller requested Evans to keep this letter private.