Nearly four decades after the Chernobyl nuclear disaster, new Lithuanian research has revealed that residents in the country’s southern and western regions, particularly those who were young children at the time, face a significantly higher lifelong risk of developing thyroid cancer, as a result of exposure to radioactive iodine from the 1986 fallout.
Although the Chernobyl disaster occurred 39 years ago, there has never been a comprehensive study assessing the long-term health consequences of the radioactive cloud that passed over Lithuania.
This year, Dr Rita Steponavičienė, oncologist and radiotherapist at the National Cancer Institute, defended her doctoral thesis on the subject, not only debunking myths but also identifying which regions of Lithuania are most at risk of thyroid cancer due to exposure to ionising radiation in late April 1986.
The eight-year study titled “The Long-Term Health Effects of the Chernobyl Nuclear Power Plant Accident in Lithuania,” aimed to assess the impact of radioactive contamination and exposure on cancer incidence and mortality in the Lithuanian population.
LRT.lt conducted an interview with Dr Steponavičienė.
Which parts of Lithuania were most affected by the Chernobyl radioactive cloud?
The southern and western regions were most affected. Weather patterns determined the distribution of radioactive fallout across different areas. For instance, residents in Biržai and the whole of northern Lithuania can rest easy.
The highest levels of ionising radiation were recorded in Klaipėda city and district, Palanga, Kretinga, Marijampolė, Varėna, Kalvarija, Pagėgiai, and Druskininkai.
Measurements taken a few days after the accident revealed that levels of radioactive iodine in those regions were dozens of times higher than normal – around 100 millisieverts. [A millisievert is a derived SI unit used to measure the equivalent dose of ionising radiation. One sievert carries with it a 5.5% chance of eventually developing fatal cancer, according to ICRP]
Receiving such a dose at once affects chemical processes in the blood and triggers irreversible changes.
For comparison, how much radiation do we typically receive in a day?
On average, a person receives about 3.8 millisieverts per year.
Where did we get this data on radiation levels, considering the consequences were being concealed at the time? Who measured them?
Our radiation safety specialists at the time. They took samples of grass, soil and cow’s milk a few days after the accident and measured levels of radioactive iodine.
Importantly, another particularly harmful radioactive element – caesium – did not fall over Lithuania. We were fortunate it didn’t rain here, as caesium is deposited through rainfall. It fell over Scandinavia instead.
Scientists noted a rise in stomach cancer cases among the Sámi population in northern Scandinavia. Investigations revealed that reindeer were grazing on caesium-contaminated vegetation, and the Sámi, consuming the meat, were exposed to radioactive caesium, increasing their cancer risk.
How much ionising radiation might residents in the affected regions have been exposed to during those unfortunate days?
It depends on several factors: the person's age at the time, whether they were outdoors, and whether they drank fresh cow’s milk or ate freshly picked plants.
The highest risk of developing thyroid cancer later in life is among those who were infants or very young children – up to around four years old – living in the most heavily contaminated areas during the accident. They could have received a dangerous dose.
What about adults?
The risk is lower for them.
After receiving a dangerous dose of ionising radiation, how long might it take for thyroid cancer to develop?
The minimum latency period is five years. On average, it’s 10 to 15 years. But the risk persists for life.
Ionising radiation affects adults and children differently. Which organs are most vulnerable?
Children and young people are far more sensitive to ionising radiation, so it affects the entire biological system.
Did you examine how many children of that age group were living in the most affected regions and how they were impacted?
Yes. We analysed the number of children in specific regions by age group and tracked the incidence of thyroid cancer from the time of the accident until 2015 – 29 years.
What were the findings?
We found a significantly higher risk and incidence of thyroid cancer. So yes, the Chernobyl disaster undoubtedly left a lasting health impact on part of our population.
Should those who are now in their early 40s and were children in those areas at the time be more proactive in checking their thyroid health?
I would say yes. An ultrasound of the thyroid is advisable – but do not panic.
Had the population been properly informed after the accident and given potassium iodide tablets in time, would the risk of cancer have been reduced?
I believe so. Even just receiving timely advice – staying indoors, avoiding cow’s milk, not eating fresh produce like freshly picked lettuce – would have helped.
It’s worth noting that our radiation safety services at the time did advise people to discard milk from the most contaminated areas. That was a very bold decision then – one Moscow might not have approved of.
For how long should cow’s milk have been avoided?
For eight days after exposure. That’s the time it takes for iodine to decay. Roughly speaking, a few weeks later, it was safe to consume milk, vegetables, berries, and so on.
Ionising radiation is not like radioactive caesium, which can contaminate land for at least 30 years. Remember how Russian soldiers, during the invasion of Ukraine, dug trenches in the so-called Red Forest near Chernobyl and suffered radiation burns.
What are some of the myths you've encountered among the public regarding the radioactive Chernobyl cloud?
The one that baffles me most is the belief that if you've been exposed to radiation, you must drink alcohol – as if vodka somehow neutralises it. I still hear people say it.
Another persistent myth is that animals in Lithuania were born with multiple heads or tails after the Chernobyl accident. That simply didn’t happen.
Back to thyroid cancer – is it true that this form of cancer is not a death sentence?
It’s one of the most treatable types of cancer and responds very well to treatment.
You studied thyroid cancer risks. What about other illnesses linked to radiation exposure?
Belarusian researchers observed a rise in breast cancer. There is also an increased risk of haematological conditions: lymphomas, leukaemia, and so on.
Nearly 7,000 Lithuanians were sent to Chernobyl to take part in clean-up operations. How many of them are still alive?
Around 4,000 are still under observation.
What have you found about the long-term health of these liquidators?
They worked on disaster mitigation for one to five months. The average radiation dose per person was about 100 milligray. Among those most exposed, we saw increased incidence of thyroid cancer, malignant brain tumours and leukaemia. There was also higher mortality from cancer, cardiovascular diseases, tuberculosis, and cerebrovascular conditions.
Among younger liquidators – those under 30 at the time – we saw notably more cases of thyroid cancer and malignant brain tumours.
Across all liquidators, there was higher mortality from cardiovascular conditions, strokes, and cancers.
You mentioned that more male liquidators contracted and died from tuberculosis. Why?
That was an unexpected finding. We can hypothesise that radiation exposure weakened their immune systems, making them more susceptible to active TB if others around them were infected.
Were there Lithuanian liquidators who developed fatal radiation sickness?
Yes, but only a few. It wasn’t as dramatic as portrayed in the well-known Chernobyl series. Not every second liquidator dropped dead like autumn leaves.
If an accident occurred at the Astravyets nuclear power plant [in Belarus, some 30 kilometres away from the Lithuanian border] and a radioactive cloud reached Lithuania, should children be given potassium iodide first?
Yes, because young people – especially children – are more sensitive to radiation. If evacuation wasn’t needed, I’d advise sealing windows and staying indoors for at least eight days.
Newsletter
Every Friday morning.
