University of Massachusetts toxicologist (and Cato adjunct scholar) Edward J. Calabrese has arrived. On October 3, he testified to the Senate Subcommittee on Superfund, Waste Management, and Regulatory Oversight, a part of the larger Committee on Environment and Public Works, chaired by John Barrasso (R‑WY).
Calabrese was asked for his expert opinion on a draft EPA proposal to consider alternative regulatory models, including ditching the “Linear‐No Threshold” (LNT) model that it employs, as does almost every other regulatory agency on earth. You can read about EPA’s proposal here.
The LNT model assumes that the first photon of ionizing radiation (or the first molecule of a carcinogen) is capable of inducing a genetic mutation (i.e. altered DNA) that can be then transmitted to future generations.
Many years ago, Calabrese went looking for the scientific basis for the LNT, for it ran counter to what he was finding in his toxicological research—that low doses of some toxins or ionizing radiation may actually confer benefits. That, of course, is also the basis for much of modern chemical pharmacology.
Try as he could, and he tried for years, he could not locate the seminal science that gave rise to the LNT. But he did find its progenitor, Hermann Muller, who claimed to have induced heritable point mutations with X‑rays in the fruit‐fly Drosophila. But where was the data and the peer‐reviewed study? Muller did author a brief article in Science on July 22, 1927, but, as Calabrese notes in his brand new paper, “He made this gene mutation claim/interpretation in an article that discussed his findings, but failed to include any data.” The Science article said the data would be in a subsequent publication.
In fact, the data underlying what may have been the most important claim in the history of regulatory science, were never published in a peer‐reviewed journal.
Nonetheless amidst public concern about atomic radiation, the National Academy of Sciences formed the Biological Effects of Atomic Radiation (BEAR‑1) panel, which reported its findings in Science in 1956. Muller was obviously highly influential, and the Science report clearly established the LNT:
Any radiation dose, however small, can induce some mutations. There is no minimum amount of radiation dose, that is, which must be exceeded before any harmful mutations occur.
Calabrese documents that Muller’s good friend and another Drosophila geneticist, Edgar Altenberg, confidentially challenged Muller’s interpretation that he was inducing point mutations. Rather, the very large doses of x‑rays that Muller subjected the fruit flies to was simply knocking out wholesale portions of the chromosomes.
But Altenburg never went public with his criticism. Perhaps, Calabrese speculates, it was because of personal loyalty and a deep relationship. When Muller attempted suicide in 1932, rather than addressing his family, his final note was to Altenburg. Muller and Altenburg ultimately lived until 1967, dying within months of each other.
Muller’s Science publication allowed him to claim research primacy, which landed him both prestige and the eventual 1946 Nobel Prize in Physiology or Medicine.
That prize validated Muller’s hypothesis and ultimately enshrined the LNT model as gospel, and it spread beyond ionizing radiation to other carcinogens and mutagens, as well as to many toxic chemicals in which, literally, the dose makes the poison. In Calabrese’s words,
…it has been Muller’s incorrect gene mutation interpretation and its legacy that created the LNT dose response model, leading to its recommendation by the US National Academy of Sciences in 1956…and then subsequently adopted by all regulatory programs throughout the world.
As a result of his recent testimony and publication, Calabrese may be changing the regulatory world.
Unlinked References:
Biological Effects of Atomic Radiation Panel, 1956. Genetic effects of atomic radiation. Science 123, 1157–64.
Muller H. J, 1927. Artificial transmutation of the gene. Science 66, 84–87
