Community Water Fluoridation and Urinary Fluoride Concentrations in a National Sample of Pregnant Women in Canada

Till, Christine; Green, Rivka; Grundy, John G.; Hornung, Richard; Neufeld, Raichel; Martínez-Mier, E. Ángeles; Ayotte, Pierre; Muckle, Gina; Lanphear, Bruce P.

doi:10.1289/ehp3546

Cited by 50 publications

(71 citation statements)

References 49 publications

(60 reference statements)

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“…Urine spot samples have been shown to be an accurate assessment of fluoride ingestion on a population basis [20]. We found similar MUF SG concentrations for pregnant women in Northern California relative to their community water fluoride concentrations, as reported by Till et al in a Canadian population [3]. Community water fluoride concentration and MUF SG were associated in both this study, and the study by Till et al, although in this study the confidence intervals for both the adjusted and unadjusted associations crossed the null.…”

Section: Discussionsupporting

confidence: 87%

“…The similarity in urine fluoride measures in Till's study of a larger cohort of Canadian women [3] and ours, supports the validity of our relatively small sample size, and underlines the usefulness of MUF as a biomarker to compare study outcomes relative to fluoride intake. However, we did not have access to information on additional possible fluoride exposure through dental products, or the use of tea, bottled drinks or water; which is a limitation to this study.…”

Section: Discussionsupporting

confidence: 79%

“…In a previous study of community water fluoride concentrations and associated MUF SG in Canada, [3], fluoridated communities had fluoride concentrations greater than 0.3 mg/L fluoride in drinking water, and nonfluoridated communities had 0.3 mg/L fluoride or less in drinking water. To compare our results with those found in the Canadian study, we compared MUF SG concentrations of pregnant women across communities with less than or greater than 0.3 mg/L fluoride in drinking water.…”

Section: Participants Primarily Resided In Communities Acrossmentioning

confidence: 84%

“…To compare our results with urine fluoride concentrations of Canadian subjects [3] in communities with high and low fluoride concentrations, we reanalyzed our data using the fluoride concentrations similar to those in the Canadian study. In this study, fluoridated communities were defined as those with 0.3 mg/L or greater fluoride in water, and non-fluoridated communities had less than 0.3 mg/L fluoride in water.…”

Section: Statistical Analysesmentioning

confidence: 99%

“…The most recent estimates posted by the US Centers for Disease Control and Prevention (CDC), are that nearly threefourths of the U.S. population with access to community water systems receive water adjusted to the federally recommended concentration of 0.7 mg/L fluoride (https://www.cdc.gov/fluoridation/statistics/2 016stats.htm). 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%

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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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Section: Discussionsupporting

confidence: 87%

Section: Discussionsupporting

confidence: 79%

Section: Participants Primarily Resided In Communities Acrossmentioning

confidence: 84%

Section: Statistical Analysesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

et al. 2020

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Maternal Urinary Fluoride and Child Neurobehavior at Age 36 Months

Malin,

Eckel,

et al. 2024

JAMA Netw Open

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ImportanceRecent studies in Canadian and Mexican populations suggest an association of higher prenatal fluoride exposure with poorer neurobehavioral development, but whether this association holds for US-based populations is unknown.ObjectiveTo examine associations of third trimester maternal urinary fluoride (MUF) with child neurobehavior at age 3 years in the US.Design, Setting, and ParticipantsThis prospective cohort study utilized urine samples archived from 2017 to 2020 and neurobehavioral data assessed from 2020 to 2023 from the Maternal and Developmental Risks from Environmental and Social Stressors (MADRES) pregnancy cohort, which consisted of predominately Hispanic women residing in Los Angeles, California. Cohort eligibility criteria at recruitment included being 18 years of age or older, less than 30 weeks’ gestation, and a fluent English or Spanish speaker. Exclusion criteria included having a disability preventing participation or provision of informed consent, being HIV positive or incarcerated, and having a multiple gestation pregnancy. There were 263 mother-child pairs who completed the 3-year study visit. In this analysis, women who reported prenatal smoking were excluded. Data analysis was conducted from October 2022 to March 2024.ExposureSpecific gravity-adjusted MUF (MUFSG), a biomarker of prenatal fluoride exposure.Main Outcomes and MeasuresNeurobehavior was quantified using the Preschool Child Behavior Checklist (CBCL), which included composite scores for Total Problems, Internalizing Problems, and Externalizing Problems. CBCL composite T scores range from 28 to 100. T scores from 60 to 63 are in the borderline clinical range, whereas scores above 63 are in the clinical range. Linear and logistic regression models adjusted for covariates were conducted.ResultsA total of 229 mother-child pairs (mean [SD] maternal age, 29.45 [5.67] years; 116 female children [50.7%] and 113 male children [49.3%]) who had MUFSG measured were included in the study. Median (IQR) MUFSG was 0.76 (0.51-1.19) mg/L, and 32 participants (14.0%) had a Total Problems T score in the borderline clinical or clinical range. A 1-IQR (0.68 mg/L) increase in MUFSG was associated with nearly double the odds of the Total Problems T score being in the borderline clinical or clinical range (odds ratio, 1.83; 95% CI, 1.17-2.86; P = .008), as well as with a 2.29-point increase in T score for the Internalizing Problems composite (B = 2.29; 95% CI, 0.47-4.11; P = .01) and a 2.14-point increase in T score for the Total Problems composite (B = 2.14; 95% CI, 0.29-3.98; P = .02).Conclusions and RelevanceIn this prospective cohort study of mother-child pairs in Los Angeles, California, prenatal fluoride exposure was associated with increased neurobehavioral problems. These findings suggest that there may be a need to establish recommendations for limiting fluoride exposure during the prenatal period.

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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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Community Water Fluoridation and Urinary Fluoride Concentrations in a National Sample of Pregnant Women in Canada

Cited by 50 publications

References 49 publications

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

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

Maternal Urinary Fluoride and Child Neurobehavior at Age 36 Months

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

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