Scientists had to invent new techniques to determine how much radiation people might have actually received. For instance, Chumak and his colleagues developed a way to estimate doses people received by analyzing tooth enamel for effects of ionizing radiation. The Kiev-based team also helped establish ways to three-dimensionally simulate the radiation fields surrounding radioactive material from the disaster.
In the end there are only a handful of rigorous studies linking Chernobyl to disease, Chumak explains. For instance, there have been at least 1,800 documented cases of thyroid cancer in children up to 14 years of age when the disaster happened, far more than normal. Children's thyroid glands are especially vulnerable, because they are prone to absorbing radioactive iodine, a by-product of the meltdown. Also, there seem to be increased levels of leukemia and cataracts at statistically significant levels among liquidators. "We're desperately looking for the effects of radiation, but we have not found more than thyroid cancer, leukemia and cataracts that is convincing," Chumak says.
There is no doubt that people who lived in the exclusion zone have suffered problems. In addition to the cancer and cataracts reported, one also sees issues with the cardiovascular, lung, digestive and kidney systems. "We see early aging in the group from the Chernobyl disaster—if we see a man from that group who is, say, 50, the medical examination might suggest he is 10 or 15 years older compared with a member of the population of Ukraine not influenced by the disaster," says Anver Gasanov, deputy chief medical officer at the Research Center for Radiation Medicine.
Whereas the obvious culprit might be radiation, however, other factors might be at play. For instance, elderly people who were allowed to resettle inside the exclusion zone actually live longer than those who were not, Chumak says.
The issue might be stress. "You have all kinds of stress connected with the disaster that can lead to bad habits, such as smoking, drinking, drugs as well as add to disorders such as depression, and that then influences other diseases they can get," Gasanov explains.
More than 350,000 people from the most severely contaminated areas were relocated, and the move from a rural or village home to a completely unfamiliar life in a city apartment for many could have been traumatic, especially for the elderly, Chumak says. And when it comes to liquidators, "there is 'victim syndrome,' where they think they are damaged beyond repair and there is no point in carrying on with their lives," he adds.
Scientists are continuing to research other potential effects of the disaster, such as whether increased incidence of mental retardation is occurring in subsequent generations due to their progenitors' radiation exposure. "We have looked at the children of victims, and now we are looking at a next generation of victims, the grandsons and granddaughters," Gasanov says.
The work done on Chernobyl is now finding use far beyond the disaster, and may be useful in assisting researchers addressing any health impacts of the latest nuclear plant disaster in Fukushima, Japan. At the same time, here in Kiev physicist Elena Bakhanova at the Research Center for Radiation Medicine is adapting the principles used to three-dimensionally model radiation fields at Chernobyl to help investigate the health effects of medical radiation.
"There are many doctors now with no training in radiology who are dealing with radiation, such as minimally invasive procedures carried out by regular cardiologists," Chumak says. "We want to learn more about the harm there might be to patients and to doctors."
Chernobyl: Timeline of a Tragedy