Recall of residential history and dietary habits during pregnancy and lactation in the distant past: reliability of questionnaire-based radiation doses for persons exposed in utero and early life

Abstract

This study evaluates the reliability of information obtained by standardized questionnaires used in by personal interviews for estimation of radiation thyroid doses of 1065 individuals in the Belarusian cohort of individuals who were exposed in utero and early life following the Chernobyl accident in April 1986. Data from two interviews conducted in 2012–2017 and in 2018–2022 with mothers, who were pregnant or gave birth shortly after the Chernobyl accident, were analysed. The most reliable answers dealt with various attributes related to residential history. In contrast, the reliability of answers regarding consumption rates of milk from privately owned cows or trade network was moderate, while the agreement in responses for consumption of milk products and leafy vegetables was fair. Information from the two interviews was used to calculate thyroid doses received by the cohort members. Specifically, ‘model-based’ thyroid doses due to ¹³¹I were estimated using input data on individual residential history and food consumption reported during the personal interviews and ecological data (¹³¹I ground deposition in the corresponding settlements). In addition, for a subset of cohort subjects (n = 205) whose mothers were measured for ¹³¹I thyroid activity, ‘measurement-based’ thyroid doses were calculated by adjusting the model-based dose using a scaling factor that is defined as the ratio of measured ¹³¹I thyroid activity to model-based ¹³¹I thyroid activity calculated for the date of measurement. A moderate agreement was observed for total (prenatal and postnatal) model-based thyroid doses due to ¹³¹I intake, the arithmetic mean ± standard deviation for the Jaccard similarity coefficient (${J}_{sim}$) was 0.45 ± 0.34 (median = 0.39), while measurement-based doses showed a much better agreement with a ${J}_{sim}$ of 0.78 ± 0.29 (median = 0.93). For model-based thyroid doses from external irradiation and from ingestion of ¹³⁴Cs and ¹³⁷Cs, ${J}_{sim}$ was 0.82 ± 0.23 (median = 0.90) and 0.84 ± 0.24 (median = 0.96), respectively. Measurement-based doses due to ingestion of radiocaesium isotopes resulted in an almost perfect agreement, ${J}_{sim}$ was 0.91 ± 0.19 (median = 1.0). The present findings suggest that long-term memory recall can be reliable, if a person is asked about unique or important life events, such as pregnancy and childbirth occurring around the time of a nuclear reactor accident. However, the substantial difference (more than 10 times) observed for model-bases doses calculated using the two questionnaires represents an important source of human factor uncertainties that needs to be considered in any dose response analyses. Other lessons learned from this study are that (i) individual measurements of radionuclides in the human body are the most valuable source of information for estimating radiation doses, and (ii) whenever a radiation accident occurs, a sample of affected people should be asked to keep a diary, if at all possible.