that low doses of radiation prompted higher rates of RIF formation than high doses, and that after low-dose exposure RIF continued to form after the radiation had ended. In 2012 a historical cohort study of over 175,000 patients without previous cancer who were examined with CT head scans in UK between 1985 and 2002 was published. The study, which investigated leukaemia and brain cancer, indicated a linear dose response in the low dose region and had qualitative estimates of risk that were in agreement with the Life Span Study (Epidemiology data for low-linear energy transfer radiation). In 2013 a data linkage study of 11 million Australians with over 680,000 people exposed to CT scans between 1985 and 2005 was published. The study confirmed the results of the 2012 UK study for leukaemia and brain cancer but also investigated other cancer types. The authors conclude that their results were generally consistent with the linear no threshold model. However, these were disputed by a 2014 French study of 67,274 patients that took into account cancer-predisposing factors among those scanned. It concluded that taking these factors into account, there is no significant excess risk from CT scans. In 2016 Jeffry A. Siegel summarised the debate between supporters and opponents of LNT as based partially in conflict between statistical and experimental inference: A 2021 study based on whole-genome sequencing of children of parents employed as liquidators in Chernobyl indicated no trans-generational genetic effects of exposure of parents to ionizing radiation. Controversy The LNT model has been contested by a number of scientists. It has been claimed that the early proponent of the model Hermann Joseph Muller intentionally ignored an early study that did not support the LNT model when he gave his 1946 Nobel Prize address advocating the model. In very high dose radiation therapy, it was known at the time that radiation can cause a physiological increase in the rate of pregnancy anomalies; however, human exposure data and animal testing suggests that the "malformation of organs appears to be a deterministic effect with a threshold dose", below which no rate increase is observed. A review in 1999 on the link between the Chernobyl accident and teratology (birth defects) concludes that "there is no substantive proof regarding radiation‐induced teratogenic effects from the Chernobyl accident". It is argued that the human body has defense mechanisms, such as DNA repair and programmed cell death, that would