The project studies the effect of low level prenatal irradiation on adult human capital with a particular focus on cognitive ability. To that end, it exploits the natural experiment generated by the Chernobyl nuclear accident that took place April 26, 1986, in Ukraine. Weather conditions in the accident's immediate aftermath meant that fallout traveled widely. Sweden received about 5 percent of fallout. The project matches adult outcomes of Swedish children born 1983-1988 to localized measures of radiocaesium taken after the accident. Variation in fallout, combined with information on date and place of birth, is used to create treatment and control groups. A study of Swedish children exposed in utero to radiation from Chernobyl fallout provides a unique opportunity to assess potential damage of irradiation at levels hitherto considered safe and/or undetectable.
This project probes the generality of the fetal origins hypothesis. In particular, it seeks to establish whether low-level radiation exposure in utero may shape subsequent cognitive outcomes. Whether these linkages exist is not currently known. Chernobyl represents a compelling natural experiment for assessing these linkages.
Broader Impact Should the preliminary results be confirmed by the full study, these findings would depart from conventional guidelines on what level of radiation exposure is safe. Thus, this work would spur additional analyses of Chernobyl fallout in other countries. Such analyses are feasible, as most of Europe east of the 7th degree east received fallout at levels comparable to Sweden; Some of these counties (e.g., Norway) produce analogous microdatasets of student outcomes. Moreover, this project plans to follow the Swedish cohort born in 1986 as they complete schooling and enter the labor market. This permits more precise assessment of the long-term economic costs of the Chernobyl accident.
Radiation exposure was not restricted to the Chernobyl accident. For example, the amount of radiation released by Chernobyl is substantially less than that released by atmospheric nuclear weapons tests. Thus, low-level radiation exposure is the rule rather than the exception. Chernobyl simply affords a particularly well-identified radiation exposure for benchmarking these effects. Therefore, this analysis helps inform the costs associated with future radiation exposures. Nuclear power is expanding in the developing world, principally in population-dense India and China. While the probability of a future meltdown can only be a speculation, nuclear power plant failures are only one source of possible exposure to radioactivity. Others include, but are not limited to the decommissioning of existing power plants, the employment of nuclear weapons or dirty bombs, heightened levels of background radiation at high altitudes (affecting frequent fliers and airline crews), radiation employed in industrial and medical treatments, and irradiation stemming from indoor exposure to radon gas and its decay products. In the event of large-scale future radiation release, this work may inform recommendations to affected populations (e.g., limiting outdoors exposure by those pregnant at the time).
This research may also improve understanding of how fetal health in general affects outcomes later in life. Knowledge of this relationship is essential to the formulation of efficient public policies. In particular, evidence of fetal origins can help identify the optimal timing over the life course of public policies that seek to improve cognitive and related socioeconomic outcomes. Finally, fetal origins provide an alternative perspective on disparities in socioeconomic outcomes. Such disparities, e.g., racial differences in average schooling rates in the U.S., are notoriously difficult to reduce. A fetal origins framework highlights the role of another well-known disparity - the wide gap by races that exists in early childhood health.
