The world has never seen a nuclear accident as severe as the one that unfolded when a reactor exploded in Chernobyl on April 26 1986, sending vast amounts of radiation into the skies around Ukraine, Belarus and Russia.
The planet had experienced massive releases like this before, in the bombings of Hiroshima and Nagasaki in 1945. But Chernobyl-related radiation exposure had a more protracted character.
It was the first time in history that such a large population, particularly at a very young age, was exposed to radioactive isotopes, namely iodine-131 and cesium-137, not just through direct exposure, but through eating contaminated food as well.
In 2006, the International Agency for Research on Cancer (IARC) published estimates of how many excess cancers would occur as a result of this contamination.
While noting that these estimates are subject to substantial uncertainty, the authors found that 1,000 cases of thyroid cancer and 4,000 cases of other cancers had already been caused by the accident. They further estimated that by 2065, 16,000 cases of thyroid cancer and 25,000 cases of other cancers could be attributed to the effects of Chernobyl radiation.
Research on the health impact of the Chernobyl disaster has mainly focused on thyroid cancer, in particular in those exposed to radioactive iodine isotopes in childhood and adolescence. Large amounts of iodine-131 were released into the atmosphere after the explosion, and children were exposed by consuming locally produced milk and vegetables.
Efforts were made to better understand the mechanisms of radiation-induced thyroid cancer and which factors could modify the radiation risk. This allowed us to identify a molecular “radiation fingerprint”, which can point to changes that are specific to radiation exposure, as opposed to any other factors.
Studies were also conducted to evaluate the risk of haematological malignancies – tumours that affect the blood, bone marrow, lymph, and lymphatic system – in children and Chernobyl clean-up workers in the three most affected countries. Studies of cancer incidence and mortality, cardiovascular diseases and all-cause mortality were also conducted on clean-up workers. Although of variable quality, the list of studies done on people affected by the blast is long.
What we found
Today, there is an overall agreement among scientist that thyroid cancers increased following exposure to radiation in childhood and adolescence. Several studies have also indicated an increase in haematological malignancies and thyroid cancer in Chernobyl clean-up workers.