E-mail Print PDF


In two recently published peer-reviewed articles, toxicologist Edward Calabrese of the University of Massachusetts Amherst describes how regulators came to adopt the linear no threshold (LNT) dose-response approach to ionizing radiation exposure in the 1950s, which was later attached to chemical carcinogen risk assessment.

He also provides supplemental evidence to his early assessments that two geneticists intentionally suppressed evidence to prevent the U.S. National Academy of Sciences (NAS) from considering an alternative, threshold model, for which there was experimental support. Calabrese's articles have been featured in two issues of Archives of Toxicology.Edward Calabrese NAS panel

"The regulatory research community needs to hear about this. This isn't an academic debate; it's practical, because all of our rules about chemical and low-level radiation are based on invalidated assumptions and scientific panel decisions made without sound evidence. Now, after all these years, it's very hard when people have been frightened to death of any exposure whatsoever, to persuade them that we don't need to be scared by certain low-dose exposures,” said Calabrese.

In the first article, Calabrese outlines the history of the LNT model for ionizing radiation mutation, a concept that was welcomed by radiation geneticists in the 1950s and recommended by national and international advisory committees for risk assessment and human exposure guidelines and later generalized to chemical carcinogens ever since. It is now available and accessible by public health and regulatory agencies worldwide.

While in his second article, Calabrese reiterates his earlier accusations that the highly revered radiation geneticist Hermann Muller, in his acceptance speech for the 1946 Nobel Prize, "made deceptive statements" intended to "promote the acceptance of the linear dose-response model for risk assessment for ionizing radiation" and that Muller's backing agenda was "masked" by long-time colleague and accomplice Curt Stern. Their actions affected "key publications in the mutation literature," enhancing acceptance of the linear dose-response and tucking "Muller's deceptions," away from vigilant eyes Calabrese notes.

Calabrese’s own career revolved around research on hormesis, which is a non-linear, threshold-based or biphasic approach to dose-response and risk assessment for ionizing radiation and toxic chemicals, supplies proof that low-dose exposure of some chemicals and ionizing radiation are benign or even helpful. In three "substantial validation tests" of the threshold, hormesis and linear no-threshold models, Calabrese and his peers say, "only the hermetic (biphasic) dose-response made consistently accurate predictions."

The UMass Amherst toxicologist has contested for many years that a second review of cancer risk assessment methods is urgently needed because the LNT model was integrated into U.S. regulatory policy based on false assumptions and by Muller and Stern's manipulation of the scientific literature.

Calabrese's claim on this particular issue is supported by letters and other materials he has obtained, many from formerly classified files. Muller and Stern had done most of their major experiments contributing to health risk assessment of ionizing radiation and Muller served on NAS's Biological Effects of Atomic Radiation (BEAR) committee through which the linear dose-response approach to risk assessment became firmly ingrained. Calabrese puts forth more evidence that illustrates the two successfully suppressed evidence from a major experiment with fruit fly sperm that challenged their views on dose-response.

These signals are relayed buying clomid online safe which then is by a number of such as medial preoptic and paraventricular nulcei.