br br br Genetic damage occurs when the DNA of sperm or egg cells are damaged. This causes a harmful characteristic that is passed on from one generation to the next. Animal studies, such as those conducted on fruit flies by Hermann J. Muller in 1926, showed that radiation will cause genetic mutations. However, to date there have been no known genetic effects in humans caused by radiation. This includes studies involving some 30,000 children of survivors of the atomic bombings of the cities of Hiroshima and Nagasaki in br br Dose limits br br To set dose limits, the CNSC has largely adopted the recommendations of the International Committee on Radiological Protection (ICRP). br br ICRP has calculated the probability of a fatal cancer by relying mainly on the assessment of radiation effects by scientific bodies such as the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) and BEIR (National Academy of Sciences, Biological Effects of Ionizing Radiation). br br The ICRP then determined what they call the overall “detriment” of radiation exposure. This includes: br br the probability of inducing a fatal cancer; br the chance of a non-fatal cancer occurring; br the chance of severe hereditary effects; and, br the length of life loss if the harm occurs (ICRP 103). br br Using all these risks, the ICRP has calculated an overall detriment of 0.042 (4.2) per sievert for adult workers and 0.057 (5.7) per sievert for the whole population (ICRP 103). br br Dose limits are set at a detriment level above which the consequences would be widely regarded as unacceptable (S24, ICRP 103). However, as a prudent measure, it is assumed that every exposure to radiation carries some risk, even if under the dose limit, so there is a regulatory requirement to reduce all doses as low as reasonably achievable, social and economic factors being taken into account. This is commonly referred to as the ALARA principle. br br The Linear No-Threshold model (LNT) is a risk model used internationally by most health agencies and nuclear regulators to set dose limits for workers and members of the public. This model plays a key role in how the CNSC approaches radiation protection. The LNT conservatively assumes there is a direct relationship between radiation exposure and cancer rates. br br As a result of these regulations, nuclear workers rarely, if ever, approach the dose limit. Doses to which the public are exposed are generally well below one-tenth of the dose limit, or about 0.1 millisieverts, even those living near nuclear facilities.