Natural radiation increases cancer risk in children

Study: Cancer risk is increased by natural radiation

02/24/2015

Regional differences in natural background radiation from the soil and the universe seem to influence children's cancer risk. This shows a new study from Switzerland. Thus, even small doses of radiation in children can promote cancer.

A study by the University of Bern shows that regional differences in natural background radiation from the soil and the universe can influence the risk of cancer in children. As reported by the Swiss National News Agency (SDA), the study provides strong evidence that even relatively small radiation doses in children promote cancer. Every year, about 200 children and adolescents under the age of 16 contract cancer in the Alpine republic, most often with blood cancer (leukemia) accounting for 30 percent of all cases, and brain tumors accounting for 20 percent.

Harmful effect has long been known
So far, the causes are largely unknown. However, ionizing radiation is a well-known environmental cause, especially for these two cancers. As the agency explains, ionizing radiation is the kind of radiation that comes from radioactive materials, for example. That high doses of it are harmful to health, would have been known for decades. For example, the effects of atomic bombings in Japan or the consequences of the meltdown in Chernobyl and Fukushima have been reported worldwide. However, the population is also exposed to a ubiquitous, natural background radiation from the earth and the universe.

How does the low, continuous dose affect?
As the University of Bern announced now, it was previously unknown how this low, continuously occurring dose over many years affects the risk of cancer in children. Because these are very low doses and rare diseases, this question had to be explored on the basis of large samples. The team led by Ben Spycher and Claudia Kuehni from the University of Bern found them in the Swiss National Cohort: this includes all children recorded in the 1990 and 2000 censuses, a total of over two million children under the age of 16.

Some children are exposed to increased radiation exposure
The researchers combined the data with radiation maps of Switzerland, with which they were able to estimate the dose rate (dose per unit time) of terrestrial and cosmic radiation at the place of residence of the children at the time of the census. With the help of the Swiss Childhood Cancer Registry, the cancers were determined after this time. As it turned out, about one percent of children in Switzerland are exposed to increased radiation levels of more than 200 nanosieverts per hour from rock or cosmos. These children were diagnosed with eleven leukemias and eight brain tumors. First author Spycher stated on request of the SDA that in children exposed to 100 nanosieverts per hour or less, the usual dose in the Central Plateau would be only six leukemia cases and about four brain tumors. Cancer risk increases by about 4% per millisievert of additional cumulative dose for both leukemia and brain tumors. The scientists said that these values ​​are similar to those of a recent study from England.

Other components of radiation exposure
According to the researchers, even regional differences such as rural and urban life, a prosperity gap or proximity to highways, power lines or radio and TV stations could not explain these risk differences. Terrestrial and cosmic radiation are only two components of the total radiation exposure of the population. Even greater is the exposure to radon, which is created by the decay of naturally occurring uranium in the ground and can penetrate via cracks in buildings. Above all, this gas increases the risk of lung cancer. In addition, medical diagnostics, such as x-rays, is a significant source of radiation. The burden thereby amounts to on average per year and person 1.2 Millisievert. This corresponds to the magnitude of the natural background radiation. And even on long flights, passengers and crew are exposed to increased cosmic radiation. (Ad)