Genetic Effects of Chernobyl Radiation

Scientific inquiries into the effects of radiation on human health have been revisited in relation to the Chernobyl accident and the nuclear accident in Japan, Fukushima, after the tsunami.

In recent years, advancements in DNA sequencing technology have allowed the examination of the genomic impacts of these events on the survivors of radiation-induced cancers.

The release of radioactive materials has resulted in contamination of the environment, including ecosystems, groundwater, agricultural products derived from the soil, and large livestock.

According to studies following these events, there is a particular concern regarding radioactive iodine (I-131), which is known to be associated with an increased risk of thyroid cancer. The primary route through which individuals could be exposed to I-131 post-nuclear events is by consuming milk obtained from cows grazing on contaminated fields.

To determine if radiation exposure could result in genetic changes passed from parents to their children, next-generation DNA sequencing and other genomic characterization tools were utilized to analyze the complete genomes of 130 individuals born between 1987 and 2002, along with their 105 parents.


The genomes of adult children were analyzed for an increase in a specific type of genetic change known as de novo mutations. De novo mutations are genetic alterations that arise randomly in an individual's gametes (sperm and eggs) and can be passed on to their offspring but are not observed in the parents.

For the range of radiation exposure experienced by the parents, there was no evidence from full genome sequencing data on de novo mutations in children born between 46 weeks and 15 years after the accident. The number of de novo mutations observed in these children was similar to that in the general population with similar characteristics.

In a second study, next-generation sequencing was used to identify genetic changes in thyroid cancers that developed in 359 individuals exposed to ionizing radiation from radioactive iodine (I-131) released during the Chernobyl nuclear accident either during childhood or in utero, compared to 81 individuals born more than nine months after the accident who were not exposed to radiation.

Energy released from ionizing radiation breaks chemical bonds within DNA, causing various types of damage. The new study emphasizes the significance of a particular type of DNA damage that encompasses breaks in both DNA strands in thyroid tumors. The relationship between DNA double-strand breaks and radiation exposure was stronger for children exposed at younger ages.


Nearly all significant gene alterations involved genes within the same signaling pathway known as the mitogen-activated protein kinase (MAPK) pathway, including BRAF, RAS, and RET genes. The affected gene set resembled those reported in previous studies on thyroid cancer. However, there was a change observed in the distribution of mutation types within these genes. Specifically, in the Chernobyl study, thyroid cancers occurring in individuals exposed to higher radiation doses during childhood were more associated with gene fusions (where both DNA strands break and incorrect pieces rejoin), while those in individuals not exposed to or exposed to lower levels of radiation were more associated with point mutations (changes in a single base pair in a gene's core).

According to the findings, DNA double-strand breaks could be an early genetic change following radiation exposure and might trigger the development of thyroid cancers.
Based on the findings of the first study, evidence demonstrating the transmission of the effects of ionizing radiation through DNA across generations, at least in the ≤1 Gy dose range studied, among nuclear disaster victims exposed to doses similar to or lower than those in the Fukushima region in Japan after the Chernobyl accident, has not been established.

However, while there are comprehensive scientific data regarding the linear relationship between ionizing radiation exposure in the ≤1 Gy dose range and DNA double-strand breaks, and its association with DNA damage and cancer risk, as there might be other mutagens that can cause DNA double-strand breaks, a reliable biomarker distinguishing radiation-induced tumors from other cancers has yet to be identified.

Future research on the potential effects of radiation exposure passing from generation to generation, particularly acute dose exposure during the conception period, could be informative. These studies form the basis for understanding the differences in risk based on dose and age for radiation-induced cancers. Further investigation into events that could initiate thyroid cancer, like ionizing radiation, and the role of DNA double-strand breaks induced by radiation in carcinogenesis is warranted.