No leukemia risk in the environment of nuclear power plants?

Study on leukemia diseases in the vicinity of nuclear power plants

07/14/2011

Again and again, a possibly increased risk of leukemia in the vicinity of nuclear power plants has been discussed in the past. Most recently, the comprehensive German study provided „Childhood cancer around nuclear power plants“ in 2007 a sensation in which a 100 percent increased blood cancer risk in children under the age of five, who live within five kilometers of one of the sixteen German nuclear power plants, was detected.

Now Swiss researchers at the University of Bern have found in the so-called Canupis (Childhood Cancer and Nuclear Power Plants in Switzerland) study, a twenty-percent increase in the risk of leukemia in infants residing within five kilometers of the Swiss nuclear power plants. However, the investigated case numbers with only eight leukemia diseases (theoretically expected to be 6.8) were too small to derive a connection with the nuclear power plants, said the researchers of the Bern University Institute for Social and Preventive Medicine (ISP). In addition, far fewer leukemia cases than those expected to be statistically significant were found in the study regions at a greater distance from nuclear power plants (five to ten kilometers or ten to fifteen kilometers), according to the Canupis study. In the end, therefore, the study does not allow any reliable statements about a possible link between leukemia and nuclear power plants.

Low significance of the cancer study due to statistical uncertainty
As part of the Canupis study, the researchers at the Bern University Institute for Social and Preventive Medicine (ISP) have closely examined the leukemia diseases of the past 25 years in Switzerland and compared them with their respective place of residence. Thus, a possibly existing connection of the leukemia illnesses with a place of residence in the proximity of the nuclear power plants should be examined. But the public is no smarter than before after the presentation of the current study on Tuesday. Because of the extremely low number of cases, the accumulation of leukemia diseases in the immediate vicinity of the nuclear power plants (radius up to five kilometers) can not be used as evidence of an increased risk of leukemia. In eight leukemia cases against 6.8 statistically expected this is „compatible with coincidence“, the researchers explained when presenting the Canupis study. A connection between the leukemia diseases and the place of residence in the vicinity of the nuclear facilities, the Swiss researchers for „unlikely“. However, they can not exclude this, because the „Observation on small numbers to a large statistical uncertainty“ led the head of the Institute for Social and Preventive Medicine, Matthias Egger.

No evidence of increased leukemia risk?
In total, the researchers analyzed the data from 1.3 million children between the ages of zero and 15 from the period from 1985 to 2009, in order to assess the possible link between leukemia and a place of residence around nuclear power plants. In the course of their investigation, the researchers divided the dwellings in the vicinity of the reactors into three different study zones. Zone I with residential areas within a radius of up to five kilometers around the nuclear power plants, zone II with residential areas within five to ten kilometers and zone III with residential areas within a radius of ten to fifteen kilometers. For Zone I, the researchers found a 20 percent increase in the number of leukemia cases, although the case numbers with eight leukemia cases were statistically expected at 6.8, but too low to make a reliable statement. In Zone II, the actual leukemia cases (12 leukemia cases) were well below the expected value of 20.3 cancers. Zone 3 also showed a slight increase in the number of leukemia cases, but with 31 leukemia cases compared to 28.3 expected, this increase does not allow conclusions to be drawn with regard to nuclear power plants, the Swiss researchers said. Overall, the number of blood cancers in the vicinity of the nuclear power plants is slightly increased, but a connection with the nuclear plants can not be derived from this, so the result of the Canupis study. However, this relationship can not be excluded on the basis of the current investigation.

Discussion about increased leukemia risk in the nuclear power plant environment
Thus, it remains controversial whether the radiation of the nuclear power plants in normal operation, in children living in the vicinity of the reactors may cause blood cancer - even if the Canupis study does not confirm such a connection. The study commissioned by the Swiss Federal Office of Public Health (FOPH) and the Swiss Cancer League (KILS) has therefore not really enriched the critical discussion on a possible link between leukemia in children living in or around nuclear power plants. „This nationwide cohort study has found little evidence for a link between living in the vicinity of a nuclear power plant and the risk of leukemia or other childhood cancer“, so the conclusion of the researchers. However, be „the statistical significance“ by virtue of „(...) limited and we can not exclude a slight increase or decrease in cases in the five-kilometer zone, especially for leukemia in children aged zero to four years,“ The scientists at the Bern University Institute for Social and Preventive Medicine explained the validity of their study.

Criticism of the validity of the current study
The Swiss president of the atomic-critical medical organization „International Doctors for the Prevention of Nuclear War / Doctors in Social Responsibility“ (IPPNW), Claudio Knüsli, said after the publication of the current study that it was methodically clean and in no way contradicted the results of the German child cancer study from 2007. However, the nuclear critic criticized that simply too few cases were investigated. „Only if the risk were significantly increased, that is, tripled, for example, can a statistically clear statement be made in so few cases“, emphasized Knüsli. Already in the run-up to the Canupis study, Knüsli had complained that Switzerland was too small for such an investigation. „You could just as well raise a coin and not have to do a lavish study that can be misused to claim that there is no link between leukemia and nuclear power plants“, so the accusation of the Swiss IPPNW president at the beginning of the study two years ago. In addition, Knüsli pointed out that in the Canupis study children are detected only from birth, but it is known, „that the embryo or the unborn child is extremely sensitive to radioactive radiation“ is. Therefore, the study should also take into account the place of residence of the mothers during pregnancy, explained the Swiss IPPNW president. (Fp)

Also read:
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How dangerous is radioactive radiation?
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Health: long-term consequences of radioactive radiation
What meltdown or super-GAU mean?
Radioactive Radiation: Health Effects


Picture credits: Angela Parszyk