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Iamandii I, De Pasquale L, Giannone ME, Veneri F, Generali L, Consolo U, Birnbaum LS, Castenmiller J, Halldorsson TI, Filippini T, Vinceti M. Does fluoride exposure affect thyroid function? A systematic review and dose-response meta-analysis. ENVIRONMENTAL RESEARCH 2024; 242:117759. [PMID: 38029816 DOI: 10.1016/j.envres.2023.117759] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2023] [Revised: 11/20/2023] [Accepted: 11/21/2023] [Indexed: 12/01/2023]
Abstract
INTRODUCTION Fluoride exposure may have various adverse health effects, including affecting thyroid function and disease risk, but the pattern of such relation is still uncertain. METHODS We systematically searched human studies assessing the relation between fluoride exposure and thyroid function and disease. We compared the highest versus the lowest fluoride category across these studies, and we performed a one-stage dose-response meta-analysis for aggregated data to explore the shape of the association. RESULTS Most retrieved studies (27 of which with a cross-sectional design) were conducted in Asia and in children, assessing fluoride exposure through its concentrations in drinking water, urine, serum, or dietary intake. Twenty-four studies reported data on thyroid function by measuring thyroid-related hormones in blood (mainly thyroid-stimulating-hormone - TSH), 9 reported data on thyroid disease, and 4 on thyroid volume. By comparing the highest versus the lowest fluoride categories, overall mean TSH difference was 1.05 μIU/mL. Dose-response curve showed no change in TSH concentrations in the lowest water fluoride exposure range, while the hormone levels started to linearly increase around 2.5 mg/L, also dependending on the risk of bias of the included studies. The association between biomarkers of fluoride exposure and TSH was also positive, with little evidence of a threshold. Evidence for an association between fluoride exposure and blood concentrations of thyroid hormones was less evident, though there was an indication of inverse association with triiodothyronine. For thyroid disease, the few available studies suggested a positive association with goiter and with hypothyroidism in both children and adults. CONCLUSIONS Overall, exposure to high-fluoride drinking water appears to non-linearly affect thyroid function and increase TSH release in children, starting above a threshold of exposure, and to increase the risk of some thyroid diseases.
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Affiliation(s)
- Inga Iamandii
- Environmental, Genetic and Nutritional Epidemiology Research Center (CREAGEN), Section of Public Health, Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Lisa De Pasquale
- Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Maria Edvige Giannone
- Environmental, Genetic and Nutritional Epidemiology Research Center (CREAGEN), Section of Public Health, Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Federica Veneri
- Department of Surgery, Medicine, Dentistry and Morphological Sciences with Transplant Surgery, Oncology and Regenerative Medicine Relevance (CHIMOMO), Unit of Dentistry & Oral-Maxillo-Facial Surgery, University of Modena and Reggio Emilia, Modena, Italy; PhD Program in Clinical and Experimental Medicine, Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Luigi Generali
- Department of Surgery, Medicine, Dentistry and Morphological Sciences with Transplant Surgery, Oncology and Regenerative Medicine Relevance (CHIMOMO), Unit of Dentistry & Oral-Maxillo-Facial Surgery, University of Modena and Reggio Emilia, Modena, Italy
| | - Ugo Consolo
- Department of Surgery, Medicine, Dentistry and Morphological Sciences with Transplant Surgery, Oncology and Regenerative Medicine Relevance (CHIMOMO), Unit of Dentistry & Oral-Maxillo-Facial Surgery, University of Modena and Reggio Emilia, Modena, Italy
| | - Linda S Birnbaum
- Nicholas School of the Environment, Duke University, Durham, NC, USA
| | - Jacqueline Castenmiller
- Office for Risk Assessment & Research, Netherlands Food and Consumer Product Safety Authority, Utrecht, the Netherlands
| | - Thorhallur I Halldorsson
- Department of Epidemiology Research, Centre for Fetal Programming, Copenhagen, Denmark; Faculty of Food Science and Nutrition, University of Iceland, Reykjavík, Iceland
| | - Tommaso Filippini
- Environmental, Genetic and Nutritional Epidemiology Research Center (CREAGEN), Section of Public Health, Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy; School of Public Health, University of California Berkeley, Berkeley, CA, USA
| | - Marco Vinceti
- Environmental, Genetic and Nutritional Epidemiology Research Center (CREAGEN), Section of Public Health, Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy; Department of Epidemiology, Boston University School of Public Health, Boston, MA, USA.
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Taher MK, Momoli F, Go J, Hagiwara S, Ramoju S, Hu X, Jensen N, Terrell R, Hemmerich A, Krewski D. Systematic review of epidemiological and toxicological evidence on health effects of fluoride in drinking water. Crit Rev Toxicol 2024; 54:2-34. [PMID: 38318766 DOI: 10.1080/10408444.2023.2295338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Accepted: 11/27/2023] [Indexed: 02/07/2024]
Abstract
INTRODUCTION Fluoride is a naturally occurring substance that is also added to drinking water, dental hygiene products, and food supplements for preventing dental caries. Concerns have been raised about several other potential health risks of fluoride. OBJECTIVE To conduct a robust synthesis of evidence regarding human health risks due to exposure to fluoride in drinking water, and to develop a point of departure (POD) for setting a health-based value (HBV) for fluoride in drinking water. METHODS A systematic review of evidence published since recent reviews of human, animal, and in vitro data was carried out. Bradford Hill considerations were used to weigh the evidence for causality. Several key studies were considered for deriving PODs. RESULTS The current review identified 89 human studies, 199 animal studies, and 10 major in vitro reviews. The weight of evidence on 39 health endpoints was presented. In addition to dental fluorosis, evidence was considered strong for reduction in IQ scores in children, moderate for thyroid dysfunction, weak for kidney dysfunction, and limited for sex hormone disruptions. CONCLUSION The current review identified moderate dental fluorosis and reduction in IQ scores in children as the most relevant endpoints for establishing an HBV for fluoride in drinking water. PODs were derived for these two endpoints, although there is still some uncertainty in the causal weight of evidence for causality for reducing IQ scores in children and considerable uncertainty in the derivation of its POD. Given our evaluation of the overall weight of evidence, moderate dental fluorosis is suggested as the key endpoint until more evidence is accumulated on possible reduction of IQ scores effects. A POD of 1.56 mg fluoride/L for moderate dental fluorosis may be preferred as a starting point for setting an HBV for fluoride in drinking water to protect against moderate and severe dental fluorosis. Although outside the scope of the current review, precautionary concerns for potential neurodevelopmental cognitive effects may warrant special consideration in the derivation of the HBV for fluoride in drinking water.
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Affiliation(s)
- Mohamed Kadry Taher
- McLaughlin Centre for Population Health Risk Assessment, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
- School of Epidemiology and Public Health, University of Ottawa, Ottawa, ON, Canada
- School of Mathematics and Statistics, Carleton University, Ottawa, ON, Canada
| | - Franco Momoli
- School of Epidemiology and Public Health, University of Ottawa, Ottawa, ON, Canada
- Risk Sciences International, Ottawa, ON, Canada
| | - Jennifer Go
- School of Epidemiology and Public Health, University of Ottawa, Ottawa, ON, Canada
- Risk Sciences International, Ottawa, ON, Canada
| | - Shintaro Hagiwara
- School of Mathematics and Statistics, Carleton University, Ottawa, ON, Canada
- Risk Sciences International, Ottawa, ON, Canada
| | - Siva Ramoju
- Risk Sciences International, Ottawa, ON, Canada
| | - Xuefeng Hu
- Department of Biology, Faculty of Science, University of Ottawa, Ottawa, ON, Canada
| | - Natalie Jensen
- School of Epidemiology and Public Health, University of Ottawa, Ottawa, ON, Canada
- Risk Sciences International, Ottawa, ON, Canada
| | - Rowan Terrell
- School of Epidemiology and Public Health, University of Ottawa, Ottawa, ON, Canada
- Risk Sciences International, Ottawa, ON, Canada
| | - Alex Hemmerich
- Risk Sciences International, Ottawa, ON, Canada
- Faculty of Education, Queen's University, Kingston, ON, Canada
| | - Daniel Krewski
- McLaughlin Centre for Population Health Risk Assessment, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
- School of Epidemiology and Public Health, University of Ottawa, Ottawa, ON, Canada
- School of Mathematics and Statistics, Carleton University, Ottawa, ON, Canada
- Risk Sciences International, Ottawa, ON, Canada
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Surya ND, Widjanarko ND, Permatasari TK, Yosephine Y, Wijaya E. Subclinical hypothyroidism and digit span test performance in children: a systematic review and meta-analysis. PAEDIATRICA INDONESIANA 2022. [DOI: 10.14238/pi62.5.2022.324-32] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Background The digit span (DS) test is one of the most commonly used neuropsychological tests to assess certain cognitive domains, i.e., short-term verbal memory, working memory, and attention. Subclinical hypothyroidism (SH) may be associated with a risk of cognitive impairment in children and adolescents.
Objective To evaluate the association between SH and DS test performance in children.
Methods Eligible studies evaluating SH and DS test performance were included in this systematic review and further assessed for risk of bias using the Newcastle Ottawa Scale. We carried out a meta-analysis using the random effects model to determine mean difference with 95% confidence interval (95%CI) for continuous data. This systematic review was conducted according to the Preview Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement.
Results Out of 1,511 participants in the five included studies, 129 had SH and 1,382 were euthyroid. The quality of all studies were fair to good. Three studies were extracted for meta-analysis, with results showing a trend toward a poorer DS test performance in the SH group compared to controls, although this difference was statistically insignificant (IV -0.57; 95%CI -1.61 to 0.46; P=0.28). There was no significant heterogeneity among the included studies (I2=0%; P=0.69).
Conclusion No significant association was noted between SH and the domains of cognitive function assessed using the DS test. Several intrinsic and extrinsic factors and inability of the DS test to detect subtle impairment may limit its usefulness in children.
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Association between Elevated Iodine Intake and IQ among School Children in Portugal. Nutrients 2022; 14:nu14214493. [PMID: 36364754 PMCID: PMC9657725 DOI: 10.3390/nu14214493] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2022] [Revised: 10/05/2022] [Accepted: 10/18/2022] [Indexed: 11/23/2022] Open
Abstract
The goal of this work was to examine whether elevated iodine intake was associated with adverse effects on IQ among school-age children in Portugal. In a representative sample of children from the north of the country, IQ percentiles by age (assessed with Raven’s Colored Progressive Matrices) were dichotomized to <50 (“below-average” IQs) and ≥50. Morning urine iodine concentrations, corrected for creatinine, were dichotomized to <250 µg/g and ≥250 µg/g, according to the European Commission/Scientific Committee on Food’s tolerable upper level of daily iodine intake for young children. Data were examined with Chi-square tests, logistic regression, and GLM univariate analysis. The sample (N = 1965) was classified as generally iodine-adequate (median urinary iodine concentration = 129 µg/L; median iodine-to-creatinine ratio = 126 µg/g) according to the WHO’s criteria. A greater proportion of children in the ≥250 µg/g group had below-average IQs, compared to children with less than 250 µg/g (p = 0.037), despite a sizable (though non-significant) proportion of children in the less-than-250 µg/g group also presenting below-average IQs, at the bottom of the iodine distribution (<50 µg/g). The proportion of below-average IQs increased with increasingly elevated iodine concentrations (p = 0.047). The association remained significant after the adjustment for confounders, with the elevated iodine group showing increased odds of having below-average IQs when compared with the non-elevated iodine group (OR 1.55; 95% CI 1.11−2.17; p = 0.011). Consistently, the former group presented a lower mean IQ than the latter (p = 0.006). High iodine intake was associated with lower IQs even in a population classified as iodine-adequate. These results bear on child cognition and on initiatives involving iodine supplementation.
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Xu LC, Zhou FF, Li M, Dai ZW, Cai KD, Zhu BX, Luo Q. The Correlation Between Low Serum T3 Levels and All-Cause and Cardiovascular Mortality in Peritoneal Dialysis Patients. Ther Clin Risk Manag 2021; 17:851-861. [PMID: 34434048 PMCID: PMC8382308 DOI: 10.2147/tcrm.s324672] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Accepted: 08/10/2021] [Indexed: 11/25/2022] Open
Abstract
Objective This study is to investigate the correlation between serum triiodothyronine (T3) levels and all-cause and cardiovascular mortality in PD patients. Methods A total of 376 end-stage renal disease (ESRD) patients who started maintenance PD treatment in the Department of Nephrology in our hospital and stable treatment for ≥3 months were selected, and the total T3 (TT3) and free T3 (FT3) levels were determined. Among them, 168 cases with FT3 <3.5 pmol/L and/or TT3 <0.92 nmol/L were divided into the low serum T3 level group, and the remaining 208 cases were divided into normal serum T3 level group. The Cox survival analysis method was used to analyze the correlation between low serum T3 levels and all-cause and cardiovascular mortality in PD patient. Results Compared with the normal serum T3 level group, patients with low serum T3 levels had higher systolic blood pressure and a higher proportion of heart disease, and lower levels of total T4, free T4, hemoglobin, serum albumin, blood calcium, serum total bilirubin, alanine aminotransferase, and 24-h urine volume (all P < 0.05). Binary Logistic regression analysis showed that heart disease (P = 0.003, OR: 2.628, 95% CI: 1.382–4.997) and high TT4 level (P < 0.001, OR: 0.968, 95% CI: 0.956–0.979) were related to low serum T3 levels in PD patients. Multivariate Cox regression analysis showed that low serum FT3 level was an independent risk factor for all-cause death in PD patients (HR = 0.633, 95% CI = 0.431–0.930; P < 0.020). Conclusion Low serum T3 levels in PD patients were associated with heart disease and TT4 levels. Low serum FT3 levels were associated with the risk of all-cause death in PD patients.
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Affiliation(s)
- Ling-Cang Xu
- Department of Nephrology, Hwa Mei Hospital, University of Chinese Academy of Sciences, Ningbo, Zhejiang Province, 315010, People's Republic of China.,Ningbo Institute of Life and Health Industry, University of Chinese Academy of Sciences, Ningbo, Zhejiang Province, 315010, People's Republic of China
| | - Fang-Fang Zhou
- Department of Nephrology, Hwa Mei Hospital, University of Chinese Academy of Sciences, Ningbo, Zhejiang Province, 315010, People's Republic of China.,Ningbo Institute of Life and Health Industry, University of Chinese Academy of Sciences, Ningbo, Zhejiang Province, 315010, People's Republic of China
| | - Meng Li
- Department of Nephrology, Hwa Mei Hospital, University of Chinese Academy of Sciences, Ningbo, Zhejiang Province, 315010, People's Republic of China.,Ningbo Institute of Life and Health Industry, University of Chinese Academy of Sciences, Ningbo, Zhejiang Province, 315010, People's Republic of China
| | - Zhi-Wei Dai
- Department of Nephrology, Hwa Mei Hospital, University of Chinese Academy of Sciences, Ningbo, Zhejiang Province, 315010, People's Republic of China.,Ningbo Institute of Life and Health Industry, University of Chinese Academy of Sciences, Ningbo, Zhejiang Province, 315010, People's Republic of China
| | - Ke-Dan Cai
- Department of Nephrology, Hwa Mei Hospital, University of Chinese Academy of Sciences, Ningbo, Zhejiang Province, 315010, People's Republic of China.,Ningbo Institute of Life and Health Industry, University of Chinese Academy of Sciences, Ningbo, Zhejiang Province, 315010, People's Republic of China
| | - Bei-Xia Zhu
- Department of Nephrology, Hwa Mei Hospital, University of Chinese Academy of Sciences, Ningbo, Zhejiang Province, 315010, People's Republic of China.,Ningbo Institute of Life and Health Industry, University of Chinese Academy of Sciences, Ningbo, Zhejiang Province, 315010, People's Republic of China
| | - Qun Luo
- Department of Nephrology, Hwa Mei Hospital, University of Chinese Academy of Sciences, Ningbo, Zhejiang Province, 315010, People's Republic of China.,Ningbo Institute of Life and Health Industry, University of Chinese Academy of Sciences, Ningbo, Zhejiang Province, 315010, People's Republic of China
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