Children of mothers exposed to high levels of radiation during the first months of pregnancy have a lower IQ
A study led by IDIAPJGol researcher Liudmila Liutsko has explored the relationship between the thyroid dose of ionizing radiation, hormone levels and intelligence in boys and girls exposed to intrauterine radiation after the Chernobyl disaster
A cohort study has followed up 500 people who were exposed during their pregnancy to radiation from the Chernobyl nuclear accident. This work, published in International Journal of Radiation Biology, suggests that the dose of intrauterine thyroid radiation that mothers received during pregnancy can be associated with the intelligence quotient of their sons and daughters.
The authors of the work have seen that foetuses who were exposed to the radiation emitted after the accident during the first weeks of pregnancy had a lower IQ at childhood than those who were exposed in an advanced phase of gestation. The radiation affected both their neurological development and their thyroid hormone levels.
The study, led by the researcher at the Institut d’Investigació en Atenció Primària Jordi Gol (IDIAPJGol), Liudmila Liutsko, highlights that there is a complex relationship between the dose of intrauterine ionizing radiation, the levels of thyroid hormones secreted during adolescence and the cognitive development of the affected people.
The work shows that having received higher doses of radiation during pregnancy and secreting more of the thyroid hormone T3 during adolescence is associated with lower IQs. It also observed significant differences between the levels of the thyroid hormones T3 and T4 between the group that was more exposed to radiation and the one that was less exposed, so that individuals in the first group had higher levels of T3 and lower levels of T4 than the second.
Disaster stress
Changes in the secretion of the T3 hormone can be produced by exposure to the ionizing radiation itself, but also by the stress experienced by pregnant women due to the disaster and subsequent evacuation. For this reason, the researchers consider the possibility that the alteration in the secretion of this hormone could be a combination of both factors.
Liutsko highlights that “in the cognitive evaluations of people subjected to high doses during pregnancy, it is necessary to consider the moment in which they were exposed to radiation.” The principal investigator of the study also recommends “offering greater radiological protection to pregnant women, especially during the first twenty weeks of gestation, so that, if it is necessary for a pregnant woman to undergo a diagnosis or treatment that involves the use of ionizing radiation, it is advisable to do it as late as possible.” The first signatory of the work adds that, "for prevention, in case of having to care for unconscious women who are not accompanied, it is better to replace, if possible, the performance of tests that involve ionizing radiation, such as CT scans or x-rays, with other non-radiating ones or use protective equipment.”
Cohort study
The research team studied two groups made up of 250 people each, born between the day of the Chernobyl nuclear accident and the following months, between April 26, 1986, and March 1, 1987. The first group included individuals with mothers who lived in heavily contaminated areas and the second, people born to mothers who lived in less contaminated areas, with lower estimated thyroid radiation doses.
This study is part of the research carried out by the International Commission on Radiological Protection (ICRP), which aims to review current evidence to adjust, if necessary, radiation standards to protect the health and well-being of future generations.
Article reference
Liutsko L, Igumnov S, Drozdovitch V, Cardis E. Association between radiation dose, thyroid hormone, and IQ levels in children exposed to radiation in utero after the Chernobyl accident. Int J Radiat Biol. 2024 May 15:1-7. doi: 10.1080/09553002.2024.2345088. Epub ahead of print. PMID: 38748999
