Scientific assumptions can shape public policy for decades, especially when conflicting evidence is overlooked or dismissed. In this historical analysis, Edward Calabrese and colleagues examine a newly uncovered 1956 letter from Nobel Prize-winning geneticist Hermann Muller that offers a surprising glimpse into one of the scientific debates that helped shape modern radiation risk assessment.

The letter concerned a dispute between Muller and fellow geneticist Milislav Demerec over the hereditary risks of radiation exposure. According to the authors, Demerec's estimates were dramatically lower than those used by the influential BEAR I Genetics Panel. Yet when Muller attempted to explain the discrepancy, he appears to have confused the panel's current debate with an entirely different disagreement from decades earlier involving fruit fly genetics rather than the bacterial data on which Demerec's estimates were based.

Calabrese and colleagues argue that the episode raises important questions about how the linear no-threshold (LNT) model became entrenched in radiation risk assessment. They suggest that dissenting evidence was discounted, influential assumptions went largely unchallenged, and scientific authority may have played an outsized role in shaping policy. The result is a case study in how unresolved scientific disputes can influence public health decisions long after the original evidence has been forgotten.