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Foat A, Stevens C, George G, Massawe J, Mhina A, Gray WK, Mmbaga BT, Rwakatema DS, Sallis P, Jarvis H, Haule I, Benedict D, Walker R. Prevalence of Skeletal Fluorosis in Northern Tanzania: A Follow-Up Study. GLOBAL HEALTH, SCIENCE AND PRACTICE 2023; 11:e2200342. [PMID: 38135514 PMCID: PMC10749641 DOI: 10.9745/ghsp-d-22-00342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Accepted: 11/19/2023] [Indexed: 12/24/2023]
Abstract
OBJECTIVES Skeletal fluorosis is a metabolic bone disease caused by excessive exposure to fluoride, predominantly through contamination of drinking water. This study aimed to identify all cases of skeletal fluorosis in Tindigani village situated in Northern Tanzania. This was done following changes in drinking water sources after a previous prevalence study in 2009 in this population. METHODS In a door-to-door cross-sectional study of Tindigani village, a sample of residents was assessed for skeletal fluorosis and dental fluorosis. Diagnosis of skeletal fluorosis was based on pre-defined angles of deformity of the lower limbs. Dental fluorosis was diagnosed and graded using the Thylstrup and Fejerskov Index. Samples from current drinking water sources underwent fluoride analysis. RESULTS Tindigani village had a population of 1,944 individuals. Of the 1,532 individuals who were screened, 45 had skeletal fluorosis, giving a prevalence of 3.3% (95% CI=2.4, 4.3). Dental fluorosis was present in 82.5% of those examined (95% CI=79.8, 85.3). Dental fluorosis was present in all individuals with skeletal fluorosis and at higher grades than in the rest of the population. Drinking water samples were collected from 28 sources. These included piped, surface, well, and borehole water sources. Fluoride concentrations ranged from 0.45-38.59 mg/L of fluoride. CONCLUSIONS Skeletal fluorosis is an ongoing but preventable health problem in the current population. The delivery of sustainable low fluoride piped water to this community would be of clear health benefit. This has been addressed at a local level.
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Affiliation(s)
- Anna Foat
- Faculty of Medical Sciences, Masters by Research, Newcastle University, Newcastle Upon Tyne, United Kingdom.
| | - Claire Stevens
- Faculty of Medical Sciences, Masters by Research, Newcastle University, Newcastle Upon Tyne, United Kingdom
| | - Grace George
- Faculty of Medical Sciences, Masters by Research, Newcastle University, Newcastle Upon Tyne, United Kingdom
| | - John Massawe
- Hai District Hospital, Boma Ng'ombe, United Republic of Tanzania
| | - Ally Mhina
- Hai District Hospital, Boma Ng'ombe, United Republic of Tanzania
| | - William K Gray
- Northumbria Healthcare NHS Foundation Trust, North Tyneside General Hospital, North Shields, United Kingdom
| | - Blandina T Mmbaga
- Kilimanjaro Clinical Research Institute, Moshi, United Republic of Tanzania
| | | | - Paul Sallis
- School of Engineering, Newcastle University, Newcastle Upon Tyne, United Kingdom
| | - Helen Jarvis
- Population Health Science Institute, Newcastle University, Newcastle Upon Tyne, United Kingdom
| | - Irene Haule
- Hai District Hospital, Boma Ng'ombe, United Republic of Tanzania
| | - Daniel Benedict
- Hai District Water Authority, Boma Ng'ombe, United Republic of Tanzania
| | - Richard Walker
- Northumbria Healthcare NHS Foundation Trust, North Tyneside General Hospital, North Shields, United Kingdom
- Population Health Science Institute, Newcastle University, Newcastle Upon Tyne, United Kingdom
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Li Y, Yin N, Cai X, Wang P, Fan C, Chang X, Liu X, Geng Z, Cui L, Du X, Cui Y. Effects of calcium supplements on oral bioavailability of fluoride in soil based on In Vivo and In Vitro methods. JOURNAL OF HAZARDOUS MATERIALS 2023; 456:131663. [PMID: 37224715 DOI: 10.1016/j.jhazmat.2023.131663] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 04/30/2023] [Accepted: 05/17/2023] [Indexed: 05/26/2023]
Abstract
Dietary calcium (Ca) intake can alleviate fluoride (F) induced fluorosis to maintain bone health. However, it is unclear whether calcium supplements can reduce the oral bioavailability of F present in contaminated soils. Here we evaluated the effects of Ca supplements on F bioavailability in three soils using an in vitro method (Physiologically Based Extraction Test) and an in vivo mouse model. Seven Ca salts, commonly used in calcium supplements, significantly reduced the F bioaccessibility in the gastric and small intestinal phases. Particularly for Ca phosphate at 150 mg Ca supplementation, F bioaccessibility in the small intestinal phase was reduced from 35.1-38.8% to 0.7-1.9% where soluble F concentrations were less than 1 mg/L. Overall, the eight Ca tablets tested in this study showed greater efficiency at decreasing F solubility. The in vitro bioaccessibility after Ca supplementation was consistent with the relative bioavailability of F. As supported by X-ray photoelectron spectroscopy, a possible mechanism is that freed F can be bound by Ca to form insoluble CaF2 and exchanged with OH groups from Al/Fe hydroxide to strongly adsorb F. These findings provide evidence of Ca supplementation in reducing health risks associated soil F exposure.
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Affiliation(s)
- Yunpeng Li
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 101408, PR China; Research Center for Eco-Environment Sciences, Chinese Academy of Sciences, Beijing 100085, PR China
| | - Naiyi Yin
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 101408, PR China; Research Center for Eco-Environment Sciences, Chinese Academy of Sciences, Beijing 100085, PR China.
| | - Xiaolin Cai
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 101408, PR China; Research Center for Eco-Environment Sciences, Chinese Academy of Sciences, Beijing 100085, PR China
| | - Pengfei Wang
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 101408, PR China; Research Center for Eco-Environment Sciences, Chinese Academy of Sciences, Beijing 100085, PR China
| | - Chuanfang Fan
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 101408, PR China; Research Center for Eco-Environment Sciences, Chinese Academy of Sciences, Beijing 100085, PR China
| | - Xuhui Chang
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 101408, PR China; Research Center for Eco-Environment Sciences, Chinese Academy of Sciences, Beijing 100085, PR China
| | - Xiaotong Liu
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 101408, PR China; Research Center for Eco-Environment Sciences, Chinese Academy of Sciences, Beijing 100085, PR China
| | - Ziqi Geng
- Sino-Danish College, University of Chinese Academy of Sciences, Beijing 101408, PR China
| | - Liwei Cui
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 101408, PR China; Research Center for Eco-Environment Sciences, Chinese Academy of Sciences, Beijing 100085, PR China
| | - Xin Du
- CHINALCO Environmental protection and Energy Conservation Group Co. Ltd., Beijing 101300, PR China
| | - Yanshan Cui
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 101408, PR China; Research Center for Eco-Environment Sciences, Chinese Academy of Sciences, Beijing 100085, PR China.
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Irigoyen-Camacho ME, Perez-Perez N, Zepeda-Zepeda MA, Velazquez-Alva MC, Castaño-Seiquer A, Barbero-Navarro I, Sanchez-Perez L. Relationships between dental fluorosis and fluoride concentrations in bottled water and groundwater in low-income children in Mexico. FRONTIERS IN ORAL HEALTH 2023; 4:1187463. [PMID: 37377524 PMCID: PMC10291056 DOI: 10.3389/froh.2023.1187463] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Accepted: 05/17/2023] [Indexed: 06/29/2023] Open
Abstract
Introduction The aim of the current study was to investigate associations between dental fluorosis in children living in low socioeconomic areas in Mexico, and fluoride concentrations in tap water, fluoride concentrations and in bottled water, and body mass index (BMI). Methods A cross-sectional study involving 585 schoolchildren aged 8-12 years was conducted in communities in a southern state of Mexico with >0.7 parts per million (ppm) fluoride in the groundwater. The Thylstrup and Fejerskov index (TFI) was used to evaluate dental fluorosis, and the World Health Organization growth standards were used to calculate age-adjusted and sex-adjusted BMI Z-scores. A BMI Z-score ≤ -1 SD was used as the cut-off point for thinness, and multiple logistic regression models for dental fluorosis (TFI ≥ 4) were constructed. Results The mean fluoride concentration in tap water was 1.39 ppm (SD 0.66), and the mean fluoride concentration in bottled water was 0.32 ppm (SD 0.23). Eighty-four children (14.39%) had a BMI Z-score ≤ -1 SD. More than half (56.1%) of the children presented with dental fluorosis in TFI categories ≥ 4. Children living in areas with higher fluoride concentrations in the tap water [odds ratio (OR) 1.57, p = 0.002] and bottled water (OR 3.03, p < .001) were more likely to have dental fluorosis in the severe categories (TFI ≥ 4). BMI Z-score was associated with the probability of dental fluorosis (TFI ≥ 4; OR 2.11, p < 0.001), and the effect size was 29.3%. Discussion A low BMI Z-score was associated with a higher prevalence of dental fluorosis in the severe category. Awareness of the fluoride concentrations in bottled water may help prevent dental fluorosis, particularly in children exposed to several high fluoride content sources. Children with a low BMI may be more vulnerable to dental fluorosis.
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Affiliation(s)
| | - Nora Perez-Perez
- School of Dentistry, Regional University of the Southeast, Oaxaca de Juárez, Mexico
| | | | | | | | | | - Leonor Sanchez-Perez
- Health Care Department, Metropolitan Autonomous University-Xochimilco, Mexico City, Mexico
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Kumar R, Sharma P, Yang W, Sillanpää M, Shang J, Bhattacharya P, Vithanage M, Maity JP. State-of-the-art of research progress on adsorptive removal of fluoride-contaminated water using biochar-based materials: Practical feasibility through reusability and column transport studies. ENVIRONMENTAL RESEARCH 2022; 214:114043. [PMID: 36029838 DOI: 10.1016/j.envres.2022.114043] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2022] [Revised: 07/15/2022] [Accepted: 08/02/2022] [Indexed: 06/15/2023]
Abstract
Fluoride (F-) is one of the essential elements found in soil and water released from geogenic sources and several anthropogenic activities. Fluoride causes fluorosis, dental and skeletal growth problems, teeth mottling, and neurological damage due to prolonged consumption, affecting millions worldwide. Adsorption is an extensively implemented technique in water and wastewater treatment for fluoride, with significant potential due to efficiency, cost-effectiveness, ease of operation, and reusability. This review highlights the current state of knowledge for fluoride adsorption using biochar-based materials and the limitations of biochar for fluoride-contaminated groundwater and industrial wastewater treatment. Biochar materials have shown significant adsorption capacities for fluoride under the influence of low pH, biochar dose, initial concentration, temperature, and co-existing ions. Modified biochar possesses various functional groups (-OH, -CC, -C-O, -CONH, -C-OH, X-OH), in which enhanced hydroxyl (-OH) groups onto the surface plays a significant role in fluoride adsorption via electrostatic attraction and ion exchange. Regeneration and reusability of biochar sorbents need to be performed to a greater extent to improve removal efficiency and reusability in field conditions. Furthermore, the present investigation identifies the limitations of biochar materials in treating fluoride-contaminated drinking groundwater and industrial effluents. The fluoride removal using biochar-based materials at an industrial scale for understanding the practical feasibility is yet to be documented. This review work recommend the feasibility of biochar-based materials in column studies for fluoride remediation in the future.
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Affiliation(s)
- Rakesh Kumar
- School of Ecology and Environment Studies, Nalanda University, Rajgir, Bihar, 803116, India
| | - Prabhakar Sharma
- School of Ecology and Environment Studies, Nalanda University, Rajgir, Bihar, 803116, India.
| | - Wen Yang
- Agronomy College, Shenyang Agricultural University, Shenyang, China
| | - Mika Sillanpää
- Department of Chemical Engineering, School of Mining, Metallurgy and Chemical Engineering, University of Johannesburg, P. O. Box 17011, Doornfontein, 2028, South Africa; Chemistry Department, College of Science, King Saud University, Riyadh, 11451, Saudi Arabia; Department of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600, Bangi, Selangor, Malaysia; International Research Centre of Nanotechnology for Himalayan Sustainability (IRCNHS), Shoolini University, Solan, 173212, Himachal Pradesh, India
| | - Jianying Shang
- Department of Soil and Water Science, China Agricultural University, Beijing, 100083, China
| | - Prosun Bhattacharya
- Department of Sustainable Development, Environmental Sciences and Engineering, KTH Royal Institute of Technology, Teknikringen, 10B SE-100 44, Stockholm, Sweden
| | - Meththika Vithanage
- Ecosphere Resilience Research Center, Faculty of Applied Sciences, University of Sri Jayewardenepura, Nugegoda, 10250, Sri Lanka; Sustainability Cluster, School of Engineering, University of Petroleum and Energy Studies, Dehradun, Uttarakhand, 248007, India
| | - Jyoti Prakash Maity
- Department of Chemistry, School of Applied Sciences, KIIT Deemed to Be University, Bhubaneswar, Odisha, 751024, India
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Goodman CV, Bashash M, Green R, Song P, Peterson KE, Schnaas L, Mercado-García A, Martínez-Medina S, Hernández-Avila M, Martinez-Mier A, Téllez-Rojo MM, Hu H, Till C. Domain-specific effects of prenatal fluoride exposure on child IQ at 4, 5, and 6-12 years in the ELEMENT cohort. ENVIRONMENTAL RESEARCH 2022; 211:112993. [PMID: 35276192 PMCID: PMC9890727 DOI: 10.1016/j.envres.2022.112993] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Revised: 02/13/2022] [Accepted: 02/19/2022] [Indexed: 05/17/2023]
Abstract
OBJECTIVE Prenatal exposure to fluoride has been associated with adverse neurodevelopmental outcomes. However, the neuropsychological profile of fluoride's developmental neurotoxicity at low levels and the stability of this relationship across childhood has not been characterized. We investigated the longitudinal and domain specific effect of prenatal fluoride exposure on IQ among children ages 4, 5, and 6-12 years in the Early Life Exposures in Mexico to Environmental Toxicants (ELEMENT) cohort. METHODS We measured the average of maternal urinary fluoride at each trimester of pregnancy adjusted for creatinine (MUFCRE). Children were administered the McCarthy Scales of Children's Abilities at ages 4 (N = 386) and 5 (N = 308), and the Wechsler Abbreviated Scale of Intelligence at age 6-12 (N = 278). We used generalized estimating equation (GEE) models to estimate the population averaged effect of MUFCRE concentration on longitudinal General Cognitive Index (GCI)/Full-Scale IQ (FSIQ), Verbal IQ (VIQ), and Performance IQ (PIQ) scores (N = 348). We tested for possible interactions between MUFCRE and child sex as well as for MUFCRE and time point on children's IQ. All models controlled for relevant available covariates. RESULTS The mean/median MUFCRE concentration was 0.90/0.83 mg/L (SD = 0.39; IQR, 0.64-1.11 mg/L). A 0.5 mg/L increase in MUFCRE predicted an average 2.12-point decrease in GCI/FSIQ (95% CI: -3.49, -0.75) and 2.63-point decrease in PIQ (95% CI: -3.87, -1.40). MUFCRE was marginally associated with VIQ across time (B = -1.29, 95% CI: -2.60, 0.01). No interactions between MUFCRE and child sex or MUFCRE and time were observed. CONCLUSION The negative association between prenatal fluoride exposure and longitudinal IQ was driven by decrements in non-verbal intelligence (i.e. PIQ), suggesting that visual-spatial and perceptual reasoning abilities may be more impacted by prenatal fluoride exposure as compared to verbal abilities.
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Affiliation(s)
- Carly V Goodman
- Faculty of Health, York University, Toronto, Ontario, Canada
| | - Morteza Bashash
- Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada
| | - Rivka Green
- Faculty of Health, York University, Toronto, Ontario, Canada
| | - Peter Song
- School of Public Health, University of Michigan, Ann Arbor, MI, USA
| | - Karen E Peterson
- School of Public Health, University of Michigan, Ann Arbor, MI, USA
| | | | | | | | | | | | | | - Howard Hu
- Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada
| | - Christine Till
- Faculty of Health, York University, Toronto, Ontario, Canada
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Tefera N, Mulualem D, Baye K, Tessema M, Woldeyohannes M, Yehualashet A, Whiting SJ. Association Between Dietary Fluoride and Calcium Intake of School-Age Children With Symptoms of Dental and Skeletal Fluorosis in Halaba, Southern Ethiopia. FRONTIERS IN ORAL HEALTH 2022; 3:853719. [PMID: 35309280 PMCID: PMC8931494 DOI: 10.3389/froh.2022.853719] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Accepted: 02/09/2022] [Indexed: 11/18/2022] Open
Abstract
Background In the Ethiopian Rift Valley, ways to reduce the fluoride (F) burden from drinking water have been unsuccessful. Calcium (Ca) intake may mitigate fluorosis by binding with F ions and preventing absorption. The purpose of this study was to examine the association between Ca intake and proportion of fluorosis symptoms in school-age children in an area where F levels are known to be higher than WHO limit of 1.5 mg F/L water. Methods A cross-sectional survey in the Halaba zone involved 135 eligible children aged 6–13 year who were recruited to have dental fluorosis assessed by a dentist and skeletal fluorosis assessed by a physiotherapist. Dietary Ca intake was determined by 24-h recall. Food items and samples from ground wells, taps and spring water were collected for F concentration. Associations were measured using bivariate logistic regression, adjusted for known confounders. Results Water F averaged 5.09 mg/L. Total F intake was high, 10.57 mg/day, and Ca intake was low, 520 mg/day. Prevalence of dental fluorosis (from very mild to severe symptoms) was 73.1% for younger children (6–8 years) and 68.3 % for older children (9–13 years). The prevalence of children having symptoms of skeletal fluorosis ranged between 55.1 and 72.4%, with no apparent age difference. Dietary F intake of children was significantly positively associated with presence of dental fluorosis. Dietary Ca intake of children was significantly negatively associated with dental fluorosis. Higher than average dietary F intake significantly increased the odds of developing skeletal fluorosis symptoms when measured as inability to stretch and fold arms to touch back of head. Higher than average Ca intake was significantly associated with decreased odds of developing skeletal fluorosis measured as inability to bend body to touch the toes or floor. Conclusions High dietary F, as expected, was associated with fluorosis in children. In the presence of higher Ca intake (>520 mg/day) some fluorosis symptoms were mitigated. There is a need to improve Ca intakes as all were below recommended levels, and this nutritional strategy may also reduce burden of excess F.
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Affiliation(s)
- Nahom Tefera
- Ethiopia and Food Science and Nutrition Research Directorate Ethiopian Public Health Institute, Center for Food Science and Nutrition, College of Natural and Computational Sciences Addis Ababa University, Addis Ababa, Ethiopia
- *Correspondence: Nahom Tefera
| | - Demmelash Mulualem
- School of Human Nutrition and Food Science, Hawassa University, Awasa, Ethiopia
| | - Kaleab Baye
- Center for Food Science and Nutrition, College of Natural and Computational Sciences Addis Ababa University, Addis Ababa, Ethiopia
| | - Masresha Tessema
- Food Science and Nutrition Research Directorate Ethiopian Public Health Institute, Addis Ababa, Ethiopia
| | - Meseret Woldeyohannes
- Food Science and Nutrition Research Directorate Ethiopian Public Health Institute, Addis Ababa, Ethiopia
| | - Asrat Yehualashet
- Food Science and Nutrition Research Directorate Ethiopian Public Health Institute, Addis Ababa, Ethiopia
| | - Susan J. Whiting
- College of Pharmacy and Nutrition, University of Saskatchewan, Saskatoon, SK, Canada
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Mulualem D, Hailu D, Tessema M, Whiting SJ. Association of Dietary Calcium Intake with Dental, Skeletal and Non-Skeletal Fluorosis among Women in the Ethiopian Rift Valley. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:ijerph19042119. [PMID: 35206307 PMCID: PMC8871530 DOI: 10.3390/ijerph19042119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 01/31/2022] [Accepted: 02/08/2022] [Indexed: 11/16/2022]
Abstract
Fluorosis is a major public health problem in the Rift Valley of Ethiopia. Low calcium (Ca) intake may worsen fluorosis symptoms. We assessed the occurrence of fluorosis symptoms among women living in high-fluoride (F) communities in South Ethiopia and their associations with dietary Ca intake. Women (n = 270) from two villages provided clinical and questionnaire data. Dental fluorosis examination was done using Dean’s Index, and skeletal and non-skeletal fluorosis assessment was carried out using physical tests and clinical symptoms. Daily Ca intake was estimated by a food frequency questionnaire. Food, drinking water and beverage samples were analyzed for F level. Many subjects (56.3%) exhibited dental fluorosis. One-third of the women were unable to perform the physical exercises indicative of skeletal fluorosis; about half had ≥2 symptoms of skeletal/non-skeletal fluorosis. The average F level in drinking water sources was ~5 mg/L. The F content in staple food samples varied from 0.8–13.6 mg/kg. Average Ca intake was 406 ± 97 mg/day. Women having ≤400 mg/day Ca intake had ~3 times greater odds of developing skeletal rigidity with joint pains [AOR = 2.8, 95%CI: 1.6, 5.0] and muscular weakness [AOR = 2.9, 95%CI: 1.3, 6.3] compared to those with higher intakes. No association of calcium intake was seen with dental fluorosis. As low dietary Ca intake was associated with symptoms related to skeletal and non-skeletal fluorosis, this warrants nutritional intervention on calcium intakes in this setting.
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Affiliation(s)
- Demmelash Mulualem
- School of Human Nutrition and Food Science, Hawassa University, Hawassa P.O. Box 5, Ethiopia;
| | - Dejene Hailu
- School of Public Health, Hawassa University, Hawassa P.O. Box 5, Ethiopia;
| | | | - Susan Joyce Whiting
- College of Pharmacy and Nutrition, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada
- Correspondence:
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Dietary fluoride intake during pregnancy and neurodevelopment in toddlers: A prospective study in the progress cohort. Neurotoxicology 2021; 87:86-93. [PMID: 34478773 PMCID: PMC8595627 DOI: 10.1016/j.neuro.2021.08.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 05/03/2021] [Accepted: 08/28/2021] [Indexed: 12/21/2022]
Abstract
Foods and beverages provide a source of fluoride exposure in Mexico. While high fluoride concentrations are neurotoxic, recent research suggests that exposures within the optimal range may also pose a risk to the developing brain. This prospective study examined whether dietary fluoride intake during pregnancy is associated with toddlers' neurodevelopment in 103 mother-child pairs from the PROGRESS cohort in Mexico City. Food and beverage fluoride intake was assessed in trimesters 2 and 3 using a food frequency questionnaire and Mexican tables of fluoride content. We used the Bayley-III to evaluate cognitive, motor, and language outcomes at 12 and 24 months of age. Adjusted linear regression models were generated for each neurodevelopment assessment time point (12 and 24 months). Mixed-effects models were used to consider a repeated measurement approach. Interactions between maternal fluoride intake and child sex on neurodevelopmental outcomes were tested. Median (IQR) dietary fluoride intake during pregnancy was 1.01 mg/d (0.73, 1.32). Maternal fluoride intake was not associated with cognitive, language, or motor outcomes collapsing across boys and girls. However, child sex modified the association between maternal fluoride intake and cognitive outcome (p interaction term = 0.06). A 0.5 mg/day increase in overall dietary fluoride intake was associated with a 3.50-point lower cognitive outcome in 24-month old boys (95 % CI: -6.58, -0.42); there was no statistical association with girls (β = 0.07, 95 % CI: -2.37, 2.51), nor on the cognitive outcome at 12-months of age. Averaging across the 12- and 24-month cognitive outcomes using mixed-effects models revealed a similar association: a 0.5 mg/day increase in overall dietary fluoride intake was associated with a 3.46-point lower cognitive outcome in boys (95 % CI: -6.23, -0.70). These findings suggest that the development of nonverbal abilities in males may be more vulnerable to prenatal fluoride exposure than language or motor abilities, even at levels within the recommended intake range.
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