Last week, Ann Coulter told America that exposure to low levels of radiation might actually be a good thing. And most of America went, "What?"
But, while Coulter seems to have overstated the case, there is, apparently, a not-widely-accepted scientific theory behind what she said. PolitiFact ended up rating Coulter's claim as "Barely True" because of hormesis—a controversial idea based on some early studies in the United States which seemed to show that regions with higher natural levels of background radiation had a lower incidence of cancer. The trouble (for Coulter) is that hormesis is far from being a proven concept.
[Fred] Mettler [a radiation expert at the University of New Mexico] cautioned not to read too much into such studies, however.
"In addition to variability in populations, statistical uncertainties, potential bias factors, and chance, on one hand there will be instances in which there was less effect than predicted," he wrote. "This is all understandable without invoking a unifying hypothesis of hormesis."
Owen Hoffman, a radiation-risk expert at Senes Oak Ridge Inc., a center for risk analysis, said that studies show low levels of radiation might eliminate some cancer but initiate others.
Hoffman also pointed to the work of Dr. Charles Land of the National Cancer Institute, who "has shown in several of his recent publications that there is considerable uncertainty in the estimation of radiation risk. In his work, he does not give much credibility to the possibility that radiation induces a protective or beneficial effect. On the other hand, he concludes that even if some credibility could be given to the possibility of a threshold or beneficial effect of radiation exposure at low doses and low dose rates, the biological and epidemiological evidence that new cancers may be initiated or promoted by radiation exposure cannot be completely ruled out."
"At present," Hoffman said, "carefully conducted epidemiological evidence does not support the presence of such beneficial effects in human populations that have been carefully monitored and followed up over time."