The Impact of Drinking Water Fluoride on the Risk of Hypothyroidism Development: A Review of the Latest Research
DOI:
https://doi.org/10.12775/QS.2026.49.67116Keywords
hypothyroidism, thyroid function, water fluoridation, fluoride, iodineAbstract
Introduction and purpose: Thyroid diseases are common endocrine disorders, with hypothyroidism being the most frequently diagnosed condition of the gland. Water fluoridation is an effective strategy for preventing dental caries, as confirmed by epidemiological studies. Despite the reported benefits, there are concerns about the risk of thyroid dysfunction with high fluoride exposure. The aim of this paper is to review the latest research on the impact of fluoride in drinking water on the risk of developing hypothyroidism.
Materials and methods: A literature search was conducted using the medical databases PubMed and Google Scholar. Articles were retrieved in English, employing the keywords: “hipothyroidism”, “thyroid function”, “water fluoridation”, “fluoride”, “iodine”.
State of Knowledge: Hypothyroidism affects approximately 4% of Europeans, with an annual incidence of 226 cases per 100,000 people. Drinking water is the main source of chronic fluoride exposure, and over 500 million people live in areas of endemic fluorosis. Numerous studies indicate a clear correlation between fluoride concentration in water and TSH levels, suggesting that excessive fluoride exposure increases the risk of hypothyroidism, which can have serious health implications, especially for pregnant women.
Summary: Recent studies confirm the correlation between fluoride exposure and the development of hypothyroidism, emphasizing the need to monitor the impact of fluoride on health.
References
1. Shaik N, Shanbhog R, Nandlal B, et al. Fluoride and thyroid function in children resident of naturally fluoridated areas consuming different levels of fluoride in drinking water: An observational study. Contemp Clin Dent. 2019;10(1):24-30 https://doi.org/10.4103/ccd.ccd_108_18
2. Iheozor-Ejiofor Z, Worthington HV, Walsh T, et al. Water fluoridation for the prevention of dental caries. Cochrane Database Syst Rev. 2015;2015(6):CD010856. https://doi.org/10.1002/14651858.CD010856.pub2
3. Aggeborn L, Öhman M. The Effects of Fluoride in Drinking Water. J Political Econ. 2021;129(2):465–491. https://doi.org/10.1086/711915
4. Iamandii I, De Pasquale L, Giannone ME, et al. Does fluoride exposure affect thyroid function? A systematic review and dose-response meta-analysis. Environ Res. 2024;242:117759. https://doi.org/10.1016/j.envres.2023.117759
5. Chaitanya NCSK, Karunakar P, Allam NSJ, et al. A systematic analysis on possibility of water fluoridation causing hypothyroidism. Indian J of Dent Res. 2018; 29(3):358-363. https://doi.org/10.4103/ijdr.IJDR_505_16
6. Zhou Q, Xue S, Zhang L, et al. Trace elements and the thyroid. Front Endocrinol (Lausanne). 2022;13:904889. https://doi.org/10.3389/fendo.2022.904889
7. Singh N, Verma KG, Verma P, et al. A comparative study of fluoride ingestion levels, serum thyroid hormone & TSH level derangements, dental fluorosis status among school children from endemic and non-endemic fluorosis areas. Springerplus. 2014;3:7. https://doi.org/10.1186/2193-1801-3-7
8. Waugh DT. Fluoride Exposure Induces Inhibition of Sodium/Iodide Symporter (NIS) Contributing to Impaired Iodine Absorption and Iodine Deficiency: Molecular Mechanisms of Inhibition and Implications for Public Health. Int J Environ Res Public Health. 2019;16(6):1086. https://doi.org/10.3390/ijerph16061086
9. National Institute for Health and Care Excellence (NICE). Thyroid disease: assessment and management. NICE Guideline, No. 145. London, 2019. https://www.ncbi.nlm.nih.gov/books/NBK550859/
10. Schneider C, Feller M, Bauer DC, et al. Initial evaluation of thyroid dysfunction - Are simultaneous TSH and fT4 tests necessary? PLoS One. 2018;13(4):e0196631. https://doi.org/10.1371/journal.pone.0196631
11. Stockigt JR. Case finding and screening strategies for thyroid dysfunction. Clin Chim Acta. 2002;315(1-2):111–124. https://doi.org/10.1016/s0009-8981(01)00715-x
12. Chaker L, Razvi S, Bensenor IM, et al. Hypothyroidism. Nat Rev Dis Primers. 2022;8(1):30. https://doi.org/10.1038/s41572-022-00357-7
13. Garmendia Madariaga A, Santos Palacios S, Guillén-Grima F, et al. The Incidence and prevalence of thyroid dysfunction in Europe: a meta-analysis. J Clin Endocrinol Metab. 2014;99(3):923–931. https://doi.org/10.1210/jc.2013-2409
14. Malin AJ, Riddell J, McCague H, et al. Fluoride exposure and thyroid function among adults living in Canada: Effect modification by iodine status. Environ Int. 2018;121(1):667–674. https://doi.org/10.1016/j.envint.2018.09.026
15. Jansen HI, Boelen A, Heijboer AC, et al. Hypothyroidism: The difficulty in attributing symptoms to their underlying cause. Front Endocrinol (Lausanne). 2023;14:1130661. https://doi.org/10.3389/fendo.2023.1130661
16. Bílek R, Dvořáková M, Grimmichová T, et al. Iodine, thyroglobulin and thyroid gland. Physiol Res. 2020;69(2):S225–S236. https://doi.org/10.33549/physiolres.934514
17. Iqbal A, Rehman A. Thyroid Uptake and Scan. In: StatPearls. Treasure Island (FL): StatPearls Publishing; 2024. https://www.ncbi.nlm.nih.gov/books/NBK555978/ (available 2024.08.08)
18. Yap YW, Onyekwelu E, Alam U. Thyroid disease in pregnancy. Clin Med (Lond). 2023;23(2):125–128. https://doi.org/10.7861/clinmed.2023-0018
19. Ferreira MKM, Nascimento PC, Bittencourt LO, et al. Is there any association between fluoride exposure and thyroid function modulation? A systematic review. PLoS One 2024;19(4):e0301911. https://doi.org/10.1371/journal.pone.0301911
20. Skórka-Majewicz M, Goschorska M, Żwierełło W, et al. Effect of fluoride on endocrine tissues and their secretory functions - review. Chemosphere. 2020;260:127565. https://doi.org/10.1016/j.chemosphere.2020.127565
21. O’Mullane DM, Baez RJ, Jones S, et al. Fluoride and Oral Health. Community Dent Health. 2016;33(2):69–99. PMID: 27352462
22. Wang M, Liu L, Li H, et al. Thyroid function, intelligence, and low-moderate fluoride exposure among Chinese school-age children. Environ Int. 2020;134:105229. https://doi.org/10.1016/j.envint.2019.105229
23. World Health Organization (WHO). Preventing disease through healthy environments: inadequate or excess fluoride: a major public health concern. World Health Organization; 2019. https://www.who.int/publications/i/item/WHO-CED-PHE-EPE-19.4.5 (available: 2024.08.08)
24. Strunecka A, Strunecky O. Mechanisms of Fluoride Toxicity: From Enzymes to Underlying Integrative Networks. Appl Sci. 2020;10(20):7100. https://doi.org/10.3390/app10207100
25. Narsimha A, Sudarshan V. Drinking water pollution with respective of fluoride in the semi-arid region of Basara, Nirmal district, Telangana State, India. Data Brief. 2018;16:752–757. https://doi.org/10.1016/j.dib.2017.11.087
26. Hall M, Lanphear B, Chevrier J, et al. Fluoride exposure and hypothyroidism in a Canadian pregnancy cohort. Sci Total Environ. 2023;869:161149. https://doi.org/10.1016/j.scitotenv.2022.161149
27. Veneri F, Vinceti M, Generali L, et al. Fluoride exposure and cognitive neurodevelopment: Systematic review and dose-response meta-analysis. Environ Res. 2023;221:115239. https://doi.org/10.1016/j.envres.2023.115239
28. Hall M, Hornung R, Chevrier J, et al. Fluoride exposure and thyroid hormone levels in pregnancy: The MIREC cohort. Environ Int. 2024;184:108442. https://doi.org/10.1016/j.envint.2024.108442
29. Whelton HP, Spencer AJ, Do LG, et al. Fluoride Revolution and Dental Caries: Evolution of Policies for Global Use. J Dent Res. 2019;98(8):837–846. https://doi.org/10.1177/0022034519843495
30. Kheradpisheh Z, Mirzaei M, Mahvi AH, et al. Impact of Drinking Water Fluoride on Human Thyroid Hormones: A Case- Control Study. Sci Rep. 2018;8:2674. https://doi.org/10.1038/s41598-018-20696-4
31. Di Jeso B, Arvan P. Thyroglobulin From Molecular and Cellular Biology to Clinical Endocrinology. Endocr Rev. 2016;37(1):2–36. https://doi.org/10.1210/er.2015-1090
32. Wei M, Ye Y, Ali MM, et al. Effect of Fluoride on Cytotoxicity Involved in Mitochondrial Dysfunction: A Review of Mechanism. Front Vet Sci. 2022;9:850771. https://doi.org/10.3389/fvets.2022.850771
33. Peckham S, Lowery D, Spencer S. Are fluoride levels in drinking water associated with hypothyroidism prevalence in England? A large observational study of GP practice data and fluoride levels in drinking water. J Epidemiol Community Health. 2015;69(7):619–624. https://doi.org/10.1136/jech-2014-204971
34. Barberio AM, Hosein FS, Quiñonez C, et al. Fluoride exposure and indicators of thyroid functioning in the Canadian population: implications for community water fluoridation. J Epidemiol Community Health. 2017;71(10):1019–1025. https://doi.org/10.1136/jech-2017-209129
35. Zulfiqar S, Rehman S, Ajaz H, et al. Correlation of Water Fluoride with Body Fluids, Dental Fluorosis and FT4, FT3 –TSH Disruption among Children in an Endemic Fluorosis area in Pakistan. Open Chem. 2019;17(1):465–474. https://doi.org/10.1515/chem-2019-0055
36. Zulfiqar S, Ajaz H, Rehman S, et al. Effect of excess Fluoride consumption on Urine-Serum Fluorides, Dental state and Thyroid Hormones among children in “Talab Sarai” Punjab Pakistan. Open Chem. 2020;18(1):119–128. https://doi.org/10.1515/chem-2020-0012
37. Susheela AK, Bhatnagar M, Vig K. Excess fluoride ingestion and thyroid hormone derangements in children living in Delhi, India. Fluoride. 2005;38(2):98–108.
38. Khandare AL, Validandi V, Gourineni SR, et al. Dose-dependent effect of fluoride on clinical and subclinical indices of fluorosis in school going children and its mitigation by supply of safe drinking water for 5 years: an Indian study. Environ Monit Assess. 2018;190(3):110. https://doi.org/10.1007/s10661-018-6501-1
39. Kumar V, Chahar P, Kajjari S, et al. Fluoride, Thyroid Hormone Derangements and its Correlation with Tooth Eruption Pattern Among the Pediatric Population from Endemic and Non-endemic Fluorosis Areas. J Contemp Dent Pract. 2018;19(12):1512–1516. PMID: 30713182
40. Hosur MB, Puranik SR, Vanaki S, et al. Study of thyroid hormones free triiodothyronine (FT3), free thyroxine (FT4) and thyroid stimulating hormone (TSH) in subjects with dental fluorosis. Eur J Dent. 2012;6(2):184–190. https://doi.org/10.1055/s-0039-1698949
41. Du Y, Zhou G, Gong B, et al. Iodine Modifies the Susceptibility of Thyroid to Fluoride Exposure in School-age Children: a Cross-sectional Study in Yellow River Basin, Henan, China. Biol Trace Elem Res. 2021;199(10):3658–3666. https://doi.org/10.1007/s12011-020-02519-8
42. Kutlucan A, Kale Koroglu B, Numan Tamer M, et al. The investigation of effects of fluorosis on thyroid volume in school-age children. Med Glas (Zenica). 2013;10(1):93–8. PMID: 23348169
43. Yang Y, Wang X, Guo X, et al. The effects of high levels of fluoride and iodine on child intellectual ability and the metabolism of fluoride and iodine. Fluoride. 2008;41(4): 336–339. PMID: 7859263
44. Zhang S, Zhang X, Liu H, et al. Modifying effect of COMT gene polymorphism and a predictive role for proteomics analysis in children’s intelligence in endemic fluorosis area in tianjin, China. Toxicol Sci. 2015;144(2):238–245. https://doi.org/10.1093/toxsci/kfu311
45. Taher MK, Momoli F, Go J, et al. Systematic review of epidemiological and toxicological evidence on health effects of fluoride in drinking water. Crit Rev Toxicol. 2024;54(1):2–34. https://doi.org/10.1080/10408444.2023.2295338
46. Griebel-Thompson A, Sands S, Chollet-Hinton L, et al. Iodine Status, Fluoride Exposure, and Thyroid Function in Pregnant Women in the United States. Curr Dev Nutr. 2022;6(1):652. https://doi.org/10.1093/cdn/nzac061.036
47. Kampouri M, Gustin K, Stråvik M, et al. Association of maternal urinary fluoride concentrations during pregnancy with size at birth and the potential mediation effect by maternal thyroid hormones: The Swedish NICE birth cohort. Environ Res. 2022; 214(4):114129. https://doi.org/10.1016/j.envres.2022.114129
Downloads
Published
How to Cite
Issue
Section
License
Copyright (c) 2026 Nicola Stencel, Jakub Szczot, Konrad Krupa, Karolina Skulimowska, Katarzyna Trela, Aleksander Tuteja, Laura Więcko, Liwia Olczyk, Klaudia Burzykowska, Kamila Gęborys
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Stats
Number of views and downloads: 123
Number of citations: 0
