Prenatal fluoride exposure and attention deficit hyperactivity disorder (ADHD) symptoms in children at 6–12 years of age in Mexico City

Bashash, Morteza; Marchand, Maelle; Hu, Howard; Till, Christine; Martínez-Mier, E. Ángeles; Sánchez, Brisa N.; Basu, Niladri; Peterson, Karen E.; Green, Rivka; Schnaas, Lourdes; Mercado‐García, Adriana; Hernández-Ávila, Mauricio; Téllez-Rojo, Martha M.

doi:10.1016/j.envint.2018.09.017

Cited by 80 publications

(72 citation statements)

References 41 publications

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“… 10 In this same cohort, MUF was also associated with more attention-deficit/hyperactivity disorder–like symptoms. 11 Urinary fluoride concentrations among pregnant women living in fluoridated communities in Canada are similar to concentrations among pregnant women living in Mexico City. 12 However, it is unclear whether fluoride exposure during pregnancy is associated with cognitive deficits in a population receiving optimally fluoridated water.…”

Section: Introductionmentioning

confidence: 85%

Association Between Maternal Fluoride Exposure During Pregnancy and IQ Scores in Offspring in Canada

et al. 2019

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IMPORTANCE The potential neurotoxicity associated with exposure to fluoride, which has generated controversy about community water fluoridation, remains unclear. OBJECTIVE To examine the association between fluoride exposure during pregnancy and IQ scores in a prospective birth cohort. DESIGN, SETTING, AND PARTICIPANTS This prospective, multicenter birth cohort study used information from the Maternal-Infant Research on Environmental Chemicals cohort. Children were born between 2008 and 2012; 41% lived in communities supplied with fluoridated municipal water. The study sample included 601 mother-child pairs recruited from 6 major cities in Canada; children were between ages 3 and 4 years at testing. Data were analyzed between March 2017 and January 2019. EXPOSURES Maternal urinary fluoride (MUF SG), adjusted for specific gravity and averaged across 3 trimesters available for 512 pregnant women, as well as self-reported maternal daily fluoride intake from water and beverage consumption available for 400 pregnant women. MAIN OUTCOMES AND MEASURES Children's IQ was assessed at ages 3 to 4 years using the Wechsler Primary and Preschool Scale of Intelligence-III. Multiple linear regression analyses were used to examine covariate-adjusted associations between each fluoride exposure measure and IQ score. RESULTS Of 512 mother-child pairs, the mean (SD) age for enrollment for mothers was 32.3 (5.1) years, 463 (90%) were white, and 264 children (52%) were female. Data on MUF SG concentrations, IQ scores, and complete covariates were available for 512 mother-child pairs; data on maternal fluoride intake and children's IQ were available for 400 of 601 mother-child pairs. Women living in areas with fluoridated tap water (n = 141) compared with nonfluoridated water (n = 228) had significantly higher mean (SD) MUF SG concentrations (0.69 [0.42] mg/L vs 0.40 [0.27] mg/L; P = .001; to convert to millimoles per liter, multiply by 0.05263) and fluoride intake levels (0.93 [0.43] vs 0.30 [0.26] mg of fluoride per day; P = .001). Children had mean (SD) Full Scale IQ scores of 107.16 (13.26), range 52-143, with girls showing significantly higher mean (SD) scores than boys: 109.56 (11.96) vs 104.61 (14.09); P = .001. There was a significant interaction (P = .02) between child sex and MUF SG (6.89; 95% CI, 0.96-12.82) indicating a differential association between boys and girls. A 1-mg/L increase in MUF SG was associated with a 4.49-point lower IQ score (95% CI, −8.38 to −0.60) in boys, but there was no statistically significant association with IQ scores in girls (B = 2.40; 95% CI, −2.53 to 7.33). A 1-mg higher daily intake of fluoride among pregnant women was associated with a 3.66 lower IQ score (95% CI, −7.16 to −0.14) in boys and girls. CONCLUSIONS AND RELEVANCE In this study, maternal exposure to higher levels of fluoride during pregnancy was associated with lower IQ scores in children aged 3 to 4 years. These findings indicate the possible need to reduce fluoride intake during pregnancy.

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Section: Introductionmentioning

confidence: 85%

Association Between Maternal Fluoride Exposure During Pregnancy and IQ Scores in Offspring in Canada

et al. 2019

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“…A number of recent studies, mainly conducted in adults [Bashash et al, 2017[Bashash et al, , 2018Thomas et al, 2016] used spot urine samples to estimate fluoride exposure and its link with several health outcomes. Although the potential of spot urine samples to predict fluoride exposure has been examined in young children [Zohouri et al, 2006;Zohoori and Maguire, 2017], its appropriateness to estimate fluoride exposure in adults has not been examined and validated.…”

Section: Discussionmentioning

confidence: 99%

Biomarkers for the Assessment of Fluoride Exposure in Children

et al. 2020

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Due to practical difficulties in quantifying fluoride exposure, the ability of various biomarkers to predict it has been investigated previously. However, the results are inadequate for validation of their application and usefulness. This study aimed to investigate the association between contemporary/recent biomarkers of fluoride exposure and total daily fluoride intake (TDFI) of children with large differences in fluoride exposure through drinking water. TDFI was assessed in 61 healthy 4 to 5 years old children who provided at least one biomarker sample; 32 lived in a low-fluoride area (0.04 mgF/L) and 29 lived in a high-fluoride area (3.05 mgF/L). Validated questionnaires were administered to evaluate fluoride intake from diets (including water) and toothpaste ingestion. Daily urinary fluoride excretion (UFE) as well as fluoride concentrations in plasma, fasting whole saliva, hair and nails (toenails/fingernails) were evaluated and related to total fluoride exposure. TDFI, UFE and fluoride concentration of biomarkers were statistically significantly higher in the high-fluoride area than in the low-fluoride area. There was a strong statistically significant positive correlation between TDFI and: UFE (ρ=0.756, p<0.001); plasma fluoride concentration (ρ=0.770, p<0.001); toenail fluoride concentration (ρ=0.604, p<0.001). The statistically significant positive correlation between TDFI and fingernail fluoride concentration (ρ=470, p<0.001) as well as between TDFI and fasting whole saliva fluoride concentration (ρ=0.453, p=0.001) was moderate, whereas it was weak between TDFI and hair fluoride concentration (ρ=0.306, p=0.027). In conclusion, the current study confirmed the suitability of 24h urine samples for estimating F exposure in children. The strong correlations between TDFI and F in plasma and toenails also suggest these biomarkers may be considered for health risk assessments of fluoride in children who are susceptible to development of dental fluorosis. Sample preparation and analysis Urine samples collected over the 24h period were pooled for each participant, and the total volume was measured. Saliva samples were centrifuged at 1000 rpm (MSE Harrier 18/80, UK) for 2 min to separate any food debris [Martínez-Mier et al., 2011]. Each blood sample was centrifuged for 10 min at 1500 rpm and the plasma collected. Nail samples from each participant (finger-and toenails , separately) were weighed, and then surface contamination from the nail clippings was removed by sonication in distilled water for 15 min [Whitford, 2005]. The cleaned samples were dried at 95ºC and weighed again. Food samples were weighed and then homogenised using an industrial blender (Cookwork BL9292, UK). Water and urine samples were analysed directly using a F ion selective electrode (ISE, 720A series; Orion Research Inc., Boston, MA, USA) after addition of TISAB III [Martínez-Mier et al., 2011]. Food, toothpaste, plasma, whole saliva, hair and nail samples were analysed after overnight hexamethyldisiloxane-acid diffusion [Martínez-Mier et a...

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“…This concentration of community water fluoridation in the US is higher than in Canada, where approximately one-third of Canadian communities fluoridate their water supply, and Europe, where only 3% of Europeans have fluoridated water [2,3]. Recent studies of the potential effects of fluoride on neurodevelopment from prenatal exposures [4][5][6][7][8], and the onset of puberty in boys [6], suggest the need to evaluate fluoride concentrations in communities in the US and their relationship to fluoride concentrations in pregnant women.…”

Section: Introductionmentioning

confidence: 99%

Maternal and fetal exposures to fluoride during mid-gestation among pregnant women in northern California

et al. 2020

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Background: Previous studies have shown a correlation between fluoride concentrations in urine and community water fluoride concentrations. However, there are no studies of the relationship between community water fluoridation, urine, serum, and amniotic fluid fluoride concentrations in pregnant women in the US. The aim of this study was to determine the relationship between maternal urine fluoride (MUF), maternal urine fluoride adjusted for specific gravity (MUF SG), maternal serum fluoride (MSF), amniotic fluid fluoride (AFF) concentrations during pregnancy, and community water fluoridation in Northern California. Methods: Archived samples of urine, serum and amniotic fluid collected from second trimester pregnant women in Northern California from 47 different communities in Northern California and one from Montana (n = 48), were analyzed for fluoride using an ion specific electrode following acid microdiffusion. Women's addresses were matched to publicly reported water fluoride concentrations. We examined whether fluoride concentrations in biospecimens differed by fluoridation status of the community water, and determined the association between water fluoride concentrations and biospecimen fluoride concentrations using linear regression models adjusted for maternal age, smoking, Body Mass Index (BMI), race/ethnicity, and gestational age at sample collection. Results: Fluoride concentrations in the community water supplies ranged from 0.02 to 1.00 mg/L. MUF, MSF , and AFF concentrations were significantly higher in pregnant women living in communities adhering to the U.S. recommended water fluoride concentration (0.7 mg/L), as compared with communities with less than 0.7 mg/L fluoride in drinking water. When adjusted for maternal age, smoking status, BMI, race/ethnicity, and gestational age at sample collection, a 0.1 mg/L increase in community water fluoride concentration was positively associated with higher concentrations of MUF (B = 0.

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Prenatal fluoride exposure and attention deficit hyperactivity disorder (ADHD) symptoms in children at 6–12 years of age in Mexico City

Cited by 80 publications

References 41 publications

Association Between Maternal Fluoride Exposure During Pregnancy and IQ Scores in Offspring in Canada

Association Between Maternal Fluoride Exposure During Pregnancy and IQ Scores in Offspring in Canada

Biomarkers for the Assessment of Fluoride Exposure in Children

Maternal and fetal exposures to fluoride during mid-gestation among pregnant women in northern California

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Prenatal fluoride exposure and attention deficit hyperactivity disorder (ADHD) symptoms in children at 6–12 years of age in Mexico City

Cited by 80 publications

References 41 publications

Association Between Maternal Fluoride Exposure During Pregnancy and IQ Scores in Offspring in Canada

Association Between Maternal Fluoride Exposure During Pregnancy and IQ Scores in Offspring in Canada

Biomarkers for the Assessment of Fluoride Exposure in Children

Maternal and fetal exposures to fluoride during mid-gestation among pregnant women in northern California

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Prenatal fluoride exposure and attention deficit hyperactivity disorder (ADHD) symptoms in children at 6–12 years of age in Mexico City