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

Khandare, Arjun L.; Validandi, Vakdevi; Gourineni, Shankar Rao; Viswanathan, Gopalan; Balakrishna, Nagalla

doi:10.1007/s10661-018-6501-1

Cited by 15 publications

(7 citation statements)

References 25 publications

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“…Clinically, elevated TSH levels often correlate with reduced T3 and T4 production, indicating a response to hormone deficiency and a need for increased production and release. This pattern was observed in studies by Khandare, Validandi [ 23 ] and [ 24 , 25 ], although [ 22 ] reported no such correlation. Moreover, while an increase in PTH is relevant, it does not directly influence thyroid functions.…”

Section: Discussionsupporting

confidence: 63%

“…The studies did not categorize participants according to life stages, such as childhood, adolescence, adulthood, middle age, or senior years. Wang, Wang [ 22 ], Kutlucan, Koroglu [ 15 ], Khandare, Validandi [ 23 ], Zulfiqar, Rehman [ 24 ] and Zulfiqar, Ajaz [ 25 ] evaluated participants ranging in age from 7 to 18 years. Conversely, Leone, Leatherwood [ 20 ] focused on adult and older individuals, with ages ranging from 18 to 60 years.…”

Section: Resultsmentioning

confidence: 99%

“…In contrast, other studies utilized various methods to assess thyroid hormones, as detailed in Table 1 , which included structural evaluation via ultrasonographic examination [ 15 ]. Five studies analyzed TSH levels, with only one [ 23 ] examining PTH levels. Baum, Börner [ 21 ] conducted multiple tests, including immunological markers such as thyroglobulin and microsomal thyroid antibody.…”

Section: Resultsmentioning

confidence: 99%

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Is there any association between fluoride exposure and thyroid function modulation? A systematic review

Ferreira,

Nascimento,

Bittencourt

et al. 2024

PLoS ONE

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Numerous pre-clinical and observational studies have explored the potential effects of fluoride (F) at varying concentrations on diverse systems and organs. While some have assessed the endocrinological conditions of children and adults, a consensus regarding the interaction between F and the thyroid remains elusive. This systematic review aimed to gather primary evidence on the association between F and changes in the thyroid at optimal and high levels in water supply as stipulated by the World Health Organization. A search strategy, incorporating terms pertinent to the studies, was employed across PubMed, Scopus, Web of Science, Lilacs, and Google Scholar. Following the review of studies, data were extracted and analyzed using the Grading of Recommendations, Assessment, Development, and Evaluations to assess the quality of the evidence. Our results yielded 3,568 studies, of which seven met the inclusion criteria for this review. Five of the seven studies identified an association between high F exposure and thyroid function. In the analysis of methodological quality, every study was found to have major or minor methodological issues and significant risk of bias. The overall confidence in the evidence was deemed low for all outcomes in the seven studies. The evidence compiled in this review suggests a potential association between chronic high levels of F exposure and thyroid damage. Nonetheless, further studies with robust design and high methodological quality are required to provide evidence for policy makers and health care practitioners.

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Section: Discussionsupporting

confidence: 63%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Is there any association between fluoride exposure and thyroid function modulation? A systematic review

Ferreira,

Nascimento,

Bittencourt

et al. 2024

PLoS ONE

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“…High levels of fluoride in drinking water can cause an increase in TSH concentrations [ 59 ]. Higher levels of fluoride in urine and levels of TSH have also been observed in children and teenagers from areas with endemic fluorosis [ 86 , 87 ]. Our findings are in line with those published by Kheradpisheh et al [ 59 ].…”

Section: Discussionmentioning

confidence: 99%

Iodine Status in Pregnant Women Having Urinary Fluoride in Contaminated Areas: A Case Study of Phayao Province

Somporn

Lapinee

Umponstira

et al. 2023

Journal of Environmental and Public Health

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Fluoride naturally occurs in the Earth’s crust and is widely dispersed in groundwater. The high consumption of fluoride can inhibit iodine metabolism in the human body, especially in the thyroid gland. This study assessed iodine knowledge, iodine consumption behavior, urinary iodine (UI), thyroid stimulating hormone (serum TSH), and free triiodothyronine3 (serum FT3) and examined the connection between fluoride exposure and UI and thyroid function as serum concentrations of TSH and FT3 in pregnant women dwelling in an area of endemic fluorosis. This was a cross-sectional study. The population included 152 pregnant women within the 1st trimester of pregnancy, during which they were provided antenatal care (ANC) in seven public community hospitals in Phayao province, Thailand. The study consisted of two components. First, the study consisted of a questionnaire in which we evaluated the iodine knowledge and iodine consumptive behaviors in subjects. Second, biochemical data were investigated to evaluate thyroid function in the subjects. The gestational age of most subjects was 8–12 weeks. The study population has lived in fluoride-contaminated areas since birth (76.97%). The iodine and iodine consumption levels were moderate (50.00%). Their food iodine consumption was 3–4 days/week, and the top five consumption ranks were iodized salt, cooked pork, eggs, sticky rice, and iodine fish sauce. In terms of biochemical parameters, 63.16% of respondents had UI levels below 150.00 g/L, which is below the normal reference range of 150.00–249.00 g/L. 89.47% of the risk of hypothyroidism was associated with serum TSH levels below 2.50 g/L. In 38.16% of the samples, normal levels of serum FT3 (2.00–4.40 pg/L) were identified in the subjects. In addition, 61.84% of the samples had FT3 concentrations greater than 4.40 pg/L (high intake of iodine). The approved association between positive serum FT3 data and serum TSH was positive (r = 260 and p < 0.05). These studies imply that these elevated levels of TSH and FT3 place pregnant women in their first trimester at risk for hypothyroidism.

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“…Fluoride exposure during early brain development has been associated with diminished intelligence quotient (IQ) scores among children living in areas with high levels of naturally occurring fluoride in drinking water (~3 mg/L) [ 1 , 2 , 3 ] and in areas where fluoride is added to public water supplies or salt for caries prevention [ 4 , 5 , 6 ]. The mechanism(s) underlying fluoride-associated cognitive deficits are not well understood, but changes to the thyroid function may be one such mechanism [ 7 , 8 , 9 , 10 , 11 ]. In 2006, the National Research Council (NRC) classified fluoride as an endocrine disruptor and recommended more research to understand fluoride’s effects on the thyroid gland, especially in iodine deficient pregnant women [ 12 ].…”

Section: Introductionmentioning

confidence: 99%

Iodine Status Modifies the Association between Fluoride Exposure in Pregnancy and Preschool Boys’ Intelligence

et al. 2022

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In animal studies, the combination of in utero fluoride exposure and low iodine has greater negative effects on offspring learning and memory than either alone, but this has not been studied in children. We evaluated whether the maternal urinary iodine concentration (MUIC) modifies the association between maternal urinary fluoride (MUF) and boys’ and girls’ intelligence. We used data from 366 mother–child dyads in the Maternal–Infant Research on Environmental Chemicals Study. We corrected trimester-specific MUF and MUIC for creatinine, and averaged them to yield our exposure variables (MUFCRE, mg/g; MUICCRE, µg/g). We assessed children’s full-scale intelligence (FSIQ) at 3 to 4 years. Using multiple linear regression, we estimated a three-way interaction between MUFCRE, MUICCRE, and child sex on FSIQ, controlling for covariates. The MUICCRE by MUFCRE interaction was significant for boys (p = 0.042), but not girls (p = 0.190). For boys whose mothers had low iodine, a 0.5 mg/g increase in MUFCRE was associated with a 4.65-point lower FSIQ score (95% CI: −7.67, −1.62). For boys whose mothers had adequate iodine, a 0.5 mg/g increase in MUFCRE was associated with a 2.95-point lower FSIQ score (95% CI: −4.77, −1.13). These results suggest adequate iodine intake during pregnancy may minimize fluoride’s neurotoxicity in boys.

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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

Cited by 15 publications

References 25 publications

Is there any association between fluoride exposure and thyroid function modulation? A systematic review

Is there any association between fluoride exposure and thyroid function modulation? A systematic review

Iodine Status in Pregnant Women Having Urinary Fluoride in Contaminated Areas: A Case Study of Phayao Province

Iodine Status Modifies the Association between Fluoride Exposure in Pregnancy and Preschool Boys’ Intelligence

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