The effect of Universal Salt Iodization on cognitive test scores in rural India

TY - JOUR

T1 - The effect of Universal Salt Iodization on cognitive test scores in rural India

AU - Tafesse, Wiktoria

N1 - Funding Information: I thank Kapil Yadav at the All Indian Institute of Medical Sciences for sharing information and data on goiter and iodine deficiency in India. I also thank ASER India for sharing their data. Moreover, I would like to thank two anonymous referees, Amalavoyal Chari, Peter Dolton, Sweta Gupta, Osea Giuntella, Leah Bevis, Ben Schwab, Nele Warrinnier, Vikram Pathania, Panu Pelkonen, Martin Chalkley as well as seminar participants at Sussex University and LICOS at KU Leuven. I am also grateful for feedback from participants at; the 2016 PhD course at the Norwegian School of Economics, the 12th Annual conference on Economic Growth and Development at the Indian Statistical Institute, the 2017 Centre for the Study of African Economies Conference, the 2017 International Health Economics Association Conference, the 2018 Royal Economic Society Annual Conference and 2018 American?European Health Economics Study Group for very helpful comments and suggestions. I acknowledge PhD funding from the ESRC during the initial time of writing the paper. Funding Information: I thank Kapil Yadav at the All Indian Institute of Medical Sciences for sharing information and data on goiter and iodine deficiency in India. I also thank ASER India for sharing their data. Moreover, I would like to thank two anonymous referees, Amalavoyal Chari, Peter Dolton, Sweta Gupta, Osea Giuntella, Leah Bevis, Ben Schwab, Nele Warrinnier, Vikram Pathania, Panu Pelkonen, Martin Chalkley as well as seminar participants at Sussex University and LICOS at KU Leuven. I am also grateful for feedback from participants at; the 2016 PhD course at the Norwegian School of Economics, the 12th Annual conference on Economic Growth and Development at the Indian Statistical Institute, the 2017 Centre for the Study of African Economies Conference, the 2017 International Health Economics Association Conference, the 2018 Royal Economic Society Annual Conference and 2018 American–European Health Economics Study Group for very helpful comments and suggestions. I acknowledge PhD funding from the ESRC during the initial time of writing the paper. Publisher Copyright: © 2021 Elsevier Ltd

PY - 2022/4/1

Y1 - 2022/4/1

N2 - This paper studies the impact of a large-scale public health intervention in early life on cognitive skills in childhood. Iodine deficiency is the most common predictor of brain damage globally which has prompted over 140 countries to implement Universal Salt Iodization. While small-scale interventions report positive effects of iodine supplementation on cognition, the causal impact of salt iodization at scale is unknown across low-income countries. This study evaluates the effect of Universal Salt Iodization on cognitive test scores of school-aged children in rural India. I exploit exogenous variation in the timing of the exposure to the policy in early life, comparing children residing in naturally iodine sufficient and deficient districts over time, using a difference-in-differences strategy. Exposure to the program increased basic numeracy and literacy skills by at least 2.4 percentage points and improved school progression. It further raised literacy scores by 6.1% of a standard deviation for girls. The effects on test scores are higher for poor children and for those residing in, or nearby, the major salt producing state where iodized salt consumption was lower at baseline. This is the first study to show that a blanket fortification policy can deliver considerable, yet heterogenous, improvements in cognition in the medium run in a developing country context.

AB - This paper studies the impact of a large-scale public health intervention in early life on cognitive skills in childhood. Iodine deficiency is the most common predictor of brain damage globally which has prompted over 140 countries to implement Universal Salt Iodization. While small-scale interventions report positive effects of iodine supplementation on cognition, the causal impact of salt iodization at scale is unknown across low-income countries. This study evaluates the effect of Universal Salt Iodization on cognitive test scores of school-aged children in rural India. I exploit exogenous variation in the timing of the exposure to the policy in early life, comparing children residing in naturally iodine sufficient and deficient districts over time, using a difference-in-differences strategy. Exposure to the program increased basic numeracy and literacy skills by at least 2.4 percentage points and improved school progression. It further raised literacy scores by 6.1% of a standard deviation for girls. The effects on test scores are higher for poor children and for those residing in, or nearby, the major salt producing state where iodized salt consumption was lower at baseline. This is the first study to show that a blanket fortification policy can deliver considerable, yet heterogenous, improvements in cognition in the medium run in a developing country context.

KW - Cognitive skills

KW - Early life

KW - Educational outcome

KW - Fetal origins

KW - Iodine deficiency disorders

KW - Universal Salt Iodization

UR - http://www.scopus.com/inward/record.url?scp=85122833178&partnerID=8YFLogxK

U2 - 10.1016/j.worlddev.2021.105796

DO - 10.1016/j.worlddev.2021.105796

M3 - Article

AN - SCOPUS:85122833178

SN - 0305-750X

VL - 152

JO - World Development

JF - World Development

M1 - 105796

ER -