Skip to main content
SpringerLink
Log in

Iodine Excess May Lead to Low Exam Score in Children Aged 8–10 Years

  • Research
  • Published:
Biological Trace Element Research Aims and scope Submit manuscript

Abstract

Recent research has shown that iodine excess may damage children’s intelligence. Years of monitoring results in Shanghai show the iodine status has approached the upper limit of the appropriate range for children aged 8–10 years, indicating a risk of iodine excess. We used multi-stage random sampling to select children. Sixteen districts of Shanghai were divided into five units based on geographic location, and one primary school was randomly selected from each unit. In each selected school, about 40 children aged 8–10 years were randomly recruited to measure their urinary iodine concentration (UIC), household salt iodine concentration (SIC), the score of the final unified exam of the last semester, and school canteen salt iodine concentration. The median UIC of 3213 children aged 8–10 years in Shanghai was 195.4 (122.0, 285.8) µg/L and exceeded 200 µg/L in 48.8% of the population. Household and school canteen iodized salt coverage rates were 60.3% and 82.5% respectively, and mean household and school canteen SICs were 21.51 ± 9.30 mg/kg and 25.29 ± 3.40 mg/kg respectively. By correcting for potential confounding factors, logistic regression demonstrated that compared to the adequate iodine status group, students in the slight iodine excess group were less likely to get “A” (score > 90) in math, Chinese, and English exams (Math: OR = 0.775, 95% CI = 0.660–0.911, P = 0.002; Chinese: OR = 0.707, 95% CI = 0.543–0.842, P < 0.001; English: OR = 0.720, 95% CI = 0.610–0.849, P < 0.001). In Shanghai, the iodine status of 8–10-year-old children is approaching the upper limit of the adequate range. Iodine excess in Shanghai may lead to low exam scores for students.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1
Fig. 2

Similar content being viewed by others

Data Availability

Details of how to access the data are available from the first author and correspondence authors.

Code Availability

Not applicable.

References

  1. Zimmermann MB (2009) Iodine deficiency. Endocr Rev 30:376–408

    Article  CAS  PubMed  Google Scholar 

  2. Zimmermann MB, Jooste PL, Pandav CS (2008) Iodine-deficiency disorders. Lancet 372:1251–1262

    Article  CAS  PubMed  Google Scholar 

  3. Zimmermann MB, Boelaert K (2015) Iodine deficiency and thyroid disorders. Lancet Diabetes Endocrinol. 3(4):286–95

    Article  CAS  PubMed  Google Scholar 

  4. Leung AM, Braverman LE (2014) Consequences of excess iodine. Nat Rev Endocrinol 10(3):136–142

    Article  CAS  PubMed  Google Scholar 

  5. Hetzel BS (1988) Iodine-deficiency disorders. Lancet 1(8599):1386–7

    Article  CAS  PubMed  Google Scholar 

  6. Zimmermann MB, Andersson M (2012) Assessment of iodine nutrition in populations: past, present, and future. Nutr Rev 70:553–570

    Article  PubMed  Google Scholar 

  7. Zimmermann MB (2013) Iodine deficiency and excess in children: worldwide status in 2013. Endocr Pract Sep-Oct 19(5):839–846

    Article  Google Scholar 

  8. Zimmermann MB, Andersson M (2021) GLOBAL ENDOCRINOLOGY: Global perspectives in endocrinology: coverage of iodized salt programs and iodine status in 2020. Eur J Endocrinol 185:R13–R21

  9. Sun D, Codling K, Chang S, Zhang S, Shen H, Su X, Chen Z, Scherpbier RW, Yan J (2017) Eliminating iodine deficiency in China: achievements, challenges and global implications. Nutrients 9(4):361

    Article  PubMed  PubMed Central  Google Scholar 

  10. Sun D, Xiao D, Liu S (2011) The monitoring of iodine deficiency disorders of China in 2011. People’s Medical Publishing House, Beijing

  11. Li F, Wan S, Zhang L, Li B, He Y, Shen H, Liu L (2022) A meta-analysis of the effect of iodine excess on the intellectual development of children in areas with high iodine levels in their drinking water. Biol Trace Elem Res 200(4):1580–1590

    Article  CAS  PubMed  Google Scholar 

  12. Wang Z, Liu P, Su X, Zou S, Song J, Liu S (2019) A comparative study of iodized salt programs: Shanghai and Switzerland. Biol Trace Elem Res 187(1):59–64

    Article  CAS  PubMed  Google Scholar 

  13. Wang Z, Zang J, Shi Z, Zhu Z, Song J, Zou S, Jin W, Jia X, Guo C, Liu S (2019) Iodine status of 8 to 10 years old children within 20 years following compulsory salt iodization policy in Shanghai. China. Nutr J 18(1):63

    Article  PubMed  Google Scholar 

  14. National Standard of the People’s Republic of China (2012) General test method in salt industry—determination of iodine (GB/T 13025.7–2012). Issued by China State Bureau of Quality and Technical Supervision

  15. The hygienic standard of the People’s Republic of China (2016) Determination of iodine in urine- Part 1: As3+ −Ce4+catalytic spectrophotometry (WS/T 107.1–2016). National Health and Family Planning Commission of the People’s Republic of China

  16. ICCIDD/UNICEF/WHO (2007) Assessment of iodine deficiency disorders and monitoring their elimination: a guide for programme managers, 3rd edn. WHO, Geneva

  17. The hygienic standard of the People’s Republic of China (2014) Screening standard for malnutrition of school-age children and adolescents (WS/T 456–2014). National Health and Family Planning Commission of the People’s Republic of China

  18. The hygienic standard of the People’s Republic of China (2018) Screening for overweight and obesity among school-age children and adolescents (WS/T 586—2018). National Health and Family Planning Commission of the People’s Republic of China

  19. Iodine Global Network. Global scorecard of iodine nutrition in 2021. Available at: https://ign.org/scorecard/. Accessed 5 May 2023

  20. Angermayr L, Clar C (2018) WITHDRAWN: iodine supplementation for preventing iodine deficiency disorders in children. Cochrane Database Syst Rev 11:CD003819

  21. World Health Assembly (‎2005)‎ Sustaining the elimination of iodine deficiency disorders. WHO, pp 112–113

  22. Li Y, Teng D, Ba J, Chen B, Du J, He L, Lai X, Teng X, Shi X, Li Y, Chi H, Liao E, Liu C, Liu L, Qin G, Qin Y, Quan H, Shi B, Sun H, Tang X, Tong N, Wang G, Zhang JA, Wang Y, Xue Y, Yan L, Yang J, Yang L, Yao Y, Ye Z, Zhang Q, Zhang L, Zhu J, Zhu M, Ning G, Mu Y, Zhao J, Shan Z, Teng W (2020) Efficacy and safety of long-term universal salt iodization on thyroid disorders: epidemiological evidence from 31 provinces of Mainland China. Thyroid 30(4):568–579

    Article  CAS  PubMed  Google Scholar 

  23. Su C, Zhang JG, Du WW, Jia XF, Huang FF, OYang YF, Li L, Bai J, Zhang XF, Wei YL, Zhang B, Wang HJ (2022) Fat intake status of pre packaged food sources among residents in 16 provinces (autonomous regions, municipalities) of China in 2018. J Hygiene Res 51(04):574–578

    Google Scholar 

  24. Wang Z, Zhu Z, Cai H, Luo B, Shi Z, Liu Y, Xiang X, Zang J, Su J (2022) The high sodium condiments and pre-packaged food should be the focus of dietary sodium control in the adult Shanghai population. Nutr Metab (Lond) 19(1):58

    Article  CAS  PubMed  Google Scholar 

  25. Zhang XF, Du WW, Zhang JG, Bai J, Yang YF, Huang FF, Wang HJ (2020) The relationship between frequency of dining out and overweight and obesity among 18–65 year old restaurant diners in six provinces of China. Chin J Health Educ 36(09):779–783, 792

  26. Wang Z, Jin W, Zhu Z, Cui X, Song Q, Shi Z, Wu C, Zang J, Guo C (2020) Relationship of household cooking salt and eating out on iodine status of pregnant women in environmental iodine-deficient coastal areas of China. Br J Nutr 124(9):971–978

    Article  CAS  PubMed  Google Scholar 

  27. Yan Y, You L, Wang X, Zhang Z, Li F, Wu H, Wu M, Zhang J, Wu J, Chen C, Li X, Xia B, Xu M, Yan L (2021) Iodine nutritional status, the prevalence of thyroid goiter and nodules in rural and urban residents: a cross-sectional study from Guangzhou. China. Endocr Connect 10(12):1550–1559

    Article  CAS  PubMed  Google Scholar 

  28. Farebrother J, Zimmermann MB, Andersson M (2019) Excess iodine intake: sources, assessment, and effects on thyroid function. Ann N Y Acad Sci 1446(1):44–65

    Article  ADS  CAS  PubMed  Google Scholar 

  29. Cui Y, Zhang Z, Zhang B, Zhao L, Hou C, Zeng Q, Nie J, Yu J, Zhao Y, Gao T, Wang A, Liu H (2018) Excessive apoptosis and disordered autophagy flux contribute to the neurotoxicity induced by high iodine in Sprague-Dawley rat. Toxicol Lett 297:24–33

    Article  CAS  PubMed  Google Scholar 

  30. Liu HL, Lam LT, Zeng Q, Han SQ, Fu G, Hou CC (2009) Effects of drinking water with high iodine concentration on the intelligence of children in Tianjin. China J Public Health (Oxf) 31(1):32–8

    Article  PubMed  Google Scholar 

  31. Wang XH, Luo XH, Wang LF, Wang JB, Qing YP, Jiang W (2008) A survey on the intelligence level of children in non iodine deficient areas of Shandong Province. In: The second Mount Taishan trace element advanced forum, pp 144–147

  32. Kampouri M, Tofail F, Rahman SM, Gustin K, Vahter M, Kippler M (2023) Gestational and childhood urinary iodine concentrations and children’s cognitive function in a longitudinal mother-child cohort in rural Bangladesh. Int J Epidemiol 52(1):144–155

    Article  PubMed  Google Scholar 

  33. Carvalho IP, Peixoto B, Caldas JC, Aa Costa, Silva S, Moreira B, Almeida A, Moreira-Rosário A, Guerra A, Delerue-Matos C, Sintra D, Pestana D, Pinto E, Mendes FC, Martins I, Leite JC, Fontoura M, Maia ML, Queirós P, Moreira R, Leal S, Norberto S, Costa V, Fernandes VC, Keating E, Azevedo L, Calhau C (2022) Association between elevated iodine intake and IQ among school children in Portugal. Nutrients 14(21):4493

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  34. Zhao JK, Zhang QL, Shang L, Hu XS, Wu BH, Liang P, Liu DC, Fei YL, Liu CF, Han DQ (2004) A study on the relationship between high iodine intake and children’s intelligence level. Chin J Public Health 05:8

    Google Scholar 

Download references

Acknowledgements

The authors are grateful to the subjects who participated in this study and to the healthcare professionals from the CDC of the sixteen districts in Shanghai.

Author information

Author notes

  1. Zhengyuan Wang and Chong Shao contributed equally to this work.

  2. Xuesong Xiang and Jiajie Zang contributed equally to this work.

Authors and Affiliations

  1. Shanghai Municipal Center for Disease Control and Prevention, Shanghai, 200336, China

    Zhengyuan Wang, Zehuan Shi, Mengying Qu, Qi Song, Liping Shen, Shupeng Mai, Wei Lu, Zhuo Sun & Jiajie Zang

  2. Department of Rheumatology and Immunology, Shanghai Tongren Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, 200050, China

    Chong Shao

  3. Baoshan Municipal Center for Disease Control and Prevention, Shanghai, 201900, China

    Yaoyan Zhu

  4. Element Nutrition of National Health Commission, National Institute of Nutrition and Health, China CDC, Beijing, 100050, China

    Xuesong Xiang

Authors
  1. Zhengyuan Wang
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Chong Shao
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Yaoyan Zhu
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Zehuan Shi
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Mengying Qu
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. Qi Song
    View author publications

    You can also search for this author in PubMed Google Scholar

  7. Liping Shen
    View author publications

    You can also search for this author in PubMed Google Scholar

  8. Shupeng Mai
    View author publications

    You can also search for this author in PubMed Google Scholar

  9. Wei Lu
    View author publications

    You can also search for this author in PubMed Google Scholar

  10. Zhuo Sun
    View author publications

    You can also search for this author in PubMed Google Scholar

  11. Xuesong Xiang
    View author publications

    You can also search for this author in PubMed Google Scholar

  12. Jiajie Zang
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

All co-authors contributed significantly to the planning of the analyses and interpretation of the data and provided essential intellectual input. Analyzed the data: Zhengyuan Wang and Yaoyan Zhu. Investigation: Chong Shao, Yaoyan Zhu, Zehuan Shi, Mengying Qu, Qi Song, Liping Shen, and Shupeng Mai. Project administration: Chong Shao, Shupeng Mai, Wei Lu, and Zhuo Sun. Writing—original draft: Zhengyuan Wang and Yaoyan Zhu. All authors read and approved the final version of the manuscript.

Corresponding author

Correspondence to Xuesong Xiang.

Ethics declarations

Ethics Approval

The study was approved by the medical ethics committee of the Shanghai Municipal Center for Disease Control and Prevention.

Consent to Participate

All guardians of participating children provided informed consent forms.

Consent for Publication

All authors approved the publication of this manuscript.

Competing Interests

The authors declare no competing interests.

Additional information

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Wang, Z., Shao, C., Zhu, Y. et al. Iodine Excess May Lead to Low Exam Score in Children Aged 8–10 Years. Biol Trace Elem Res 202, 1468–1476 (2024). https://doi.org/10.1007/s12011-023-03783-0

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s12011-023-03783-0

Keywords

Search

Navigation