As we watch Putin and Russia invade Ukraine, we can think back to one of the things that the Soviet Union gave to the Ukrainian people before they became independent in 1991. This, of course, is the Chernobyl disaster.
The Chernobyl nuclear power plant suffered an accident on April 26, 1986.There was an explosion in nuclear reactor number 4. I cannot recount all the factors that led to this disaster, but it apparently stemmed from numerous defects and errors synergizing at the same time, including that it occurred during the change of shift from the day shift to the evening shift, and that the radiation dosimeters were defective and did not properly record the ambient radiation so the crew and the chief were unaware of the mounting radiation. Thus, a whole slew of failsafe mechanisms failed.
At the time of the accident, the nearest town was Priyat, population about 49,000, 2 kilometers away, but no alarms were immediately raised. It took 36 hours before the alarm was raised and Priyat was evacuated, and then subsequently a larger exclusion zone was created of about 30 kilometers radius which excluded about 130,000 people, and ultimately an even larger zone was created from which 350,000 people were evacuated.
In the initial accident, two engineers died and about 50 others developed radiation sickness, but these numbers soon increased; the best estimates are that about 60 died from acute radiation sickness. But radioisotopes were released into the atmosphere and spread both over the Chernobyl area as well as into adjoining countries, notably Belarus, whose border is 15 kilometers away. The main radioisotope in the emissions was radioactive iodine (I-131).
Iodine is taken up in the body by the thyroid gland and used to make thyroid hormones. Under normal circumstances, we obtain it primarily from fish and iodized salt. So radioactive iodine will be taken up by and concentrated in the thyroid and pose a carcinogenic risk to that organ. Modeling studies conducted by a number of agencies at the time estimated that this was likely to lead to an excess of 4,000 thyroid cancers in the region due to this problem; ultimately, the best estimate is that there were actually over 11,000 excess thyroid cancer cases. In Belarus in the years prior to the accident, there were 3-8 cases of thyroid cancer annually among children. By 5 years after the accident, the number of thyroid cancers annually among children had increased to 90 or more. A similar tenfold increase occurred among adults. In addition, studies indicated that the thyroid cancers diagnosed were also more aggressive than typical thyroid cancers. Studies of children in the Ukraine also showed dramatic increases in risk of thyroid cancer.
There were relatively fewer studies among adults. Most of these were among clean-up workers and did confirm an increased risk of thyroid cancer, though not as dramatic as among children. There were also studies that suggested an increased risk of leukemia and other hematopoietic tumors, but these were less definitive.
The radioactive fallout from Chernobyl was not confined to the Soviet Union. It spread over much of Europe. Thus, several studies have been conducted to estimate how much this may have increased the cancer burden in Europe. Of course, this is not an easy quantity to estimate and is subject to a large degree of uncertainty, but the best estimates seem to be that about 1,000 extra cases of thyroid cancer have occurred in Europe over the past 25 years due to the Chernobyl accident. There are probably other malignancies as well.
One study published in Connecticut used data from the Connecticut Tumor Registry, perhaps the best source of information on cancer statistics over time in the United States. This study found that thyroid cancer rates had risen in Connecticut in the ten years following Chernobyl. The authors indicated that similar increases had occurred after other nuclear accidents as well and that fallout could spread that far.
We should also bear in mind that there are large populations of immigrants from the countries involved —Ukraine, Belarus, Russia —in the United States. Many of these immigrated after 1986 and thus suffered the exposures. It is estimated that there are over 700,000 such immigrants in the U.S., of which over 200,000 are in New York City, with substantial others in the NYC suburbs and New Jersey. Concern has been raised among various clinical groups about thyroid cancer rates in these populations. Thyroid cancer rates in the U.S. have been rising generally, so it may be hard to discern an increase among specific immigrant groups. Thyroid cancer rates did rise faster in New York and Brooklyn than in the rest of the country and that may represent in part an effect among these immigrants. In 2006, twenty years after the accident, New York State provided funds for thyroid screening among these immigrant populations in Brooklyn in response to these concerns.
Alfred I. Neugut, MD, PhD, is a medical oncologist and cancer epidemiologist at Columbia University Irving Medical Center/New York Presbyterian and Mailman School of Public Health in New York.
This article is for educational purposes only and is not intended to be a substitute for professional medical advice, diagnosis, or treatment, and does not constitute medical or other professional advice. Always seek the advice of your qualified health provider with any questions you may have regarding a medical condition or treatment.
