© 2025 American Dental Association l 71
Fluoridation Facts
100 100.2 108.21 101.47 104.69 109.1
99.8 98.1 108.07 98.67 104.62 108.6
0
20
40
60
80
100
120
140
Broadbent 2015 (Child) Broadbent 2015 (Adult) Green 2019 Ibarluzea 2022 Dewey 2023 Do 2024
Studies
Fluoridated Non-Fluoridated
comparable to those in the low-fluoride areas used as controls in these studies. The following reviews
support the safety of community water fluoridation at recommended levels:
• Kumar et al. (2023): A meta-analysis of eight studies conducted in areas relevant to
community water fluoridation (less than 1.5 mg/L in drinking water or urine) found no association
between fluoride exposure and IQ.29 As of 2024, five studies comparing mean IQ scores between
fluoridated and non-fluoridated areas are available and show no difference in IQ scores (Figure 5:
Mean IQ or cognition scores (unadjusted) by fluoridation status.29)
• Broadbent et al. (2015): This population-based birth cohort study in New Zealand found no
association between early-life exposure to fluorides and IQ during childhood or in adulthood.322
• Green et al. (2019): This prospective birth cohort study in Canada examined the association
between maternal fluoride exposures and children’s IQ at ages 3–4 years. The study’s analysis
used the biobank of specimens from the Maternal-Infant Research on Environmental Chemicals
(MIREC) study. The study found that maternal urinary fluoride adjusted for specific gravity
(MUFSG) was not associated with full-scale IQ (FSIQ). However, when the data were analyzed
by sex, MUFSG was associated with FSIQ in boys, but not girls. The authors cited the lack of data
on fluoride exposures or consumption during infancy and childhood as a limitation.323
• Ibarluzea et al. (2022): This study examined mother-child dyads from the Infancia y Medio
Ambiente (Childhood and Environmen) birth cohort project in Spain. Researchers replicated the
Canadian mother-child dyad studies but reported completely opposite results. The study found
that maternal urinary fluoride across the pregnancy was associated with significantly increased
McCarthy scores in boys for the verbal, performance, numeric, and memory domains and
General Cognitive Index, but was not significantly associated for girls.324
• Dewey et al. 2023: This prospective ecological cohort study found no association between fluoride
exposure and FSIQ in preschool children in Alberta, Canada. However, exposure to fluoridated drinking
water throughout pregnancy was associated with poorer performance on the Gift Delay test.325
• Do et al. 2023: This study of schoolchildren in Australia found that exposure to fluoridated
water during the first 5 years of life was not associated with altered measures of children’s
emotional or behavioral development or executive functioning.326
Figure 5: Mean IQ Scores (Fluoridated versus Non-fluoridated) (unadjusted)
by Fluoridation Status
IQ
or
Cognition
Scores
Fluoridation Facts
100 100.2 108.21 101.47 104.69 109.1
99.8 98.1 108.07 98.67 104.62 108.6
0
20
40
60
80
100
120
140
Broadbent 2015 (Child) Broadbent 2015 (Adult) Green 2019 Ibarluzea 2022 Dewey 2023 Do 2024
Studies
Fluoridated Non-Fluoridated
comparable to those in the low-fluoride areas used as controls in these studies. The following reviews
support the safety of community water fluoridation at recommended levels:
• Kumar et al. (2023): A meta-analysis of eight studies conducted in areas relevant to
community water fluoridation (less than 1.5 mg/L in drinking water or urine) found no association
between fluoride exposure and IQ.29 As of 2024, five studies comparing mean IQ scores between
fluoridated and non-fluoridated areas are available and show no difference in IQ scores (Figure 5:
Mean IQ or cognition scores (unadjusted) by fluoridation status.29)
• Broadbent et al. (2015): This population-based birth cohort study in New Zealand found no
association between early-life exposure to fluorides and IQ during childhood or in adulthood.322
• Green et al. (2019): This prospective birth cohort study in Canada examined the association
between maternal fluoride exposures and children’s IQ at ages 3–4 years. The study’s analysis
used the biobank of specimens from the Maternal-Infant Research on Environmental Chemicals
(MIREC) study. The study found that maternal urinary fluoride adjusted for specific gravity
(MUFSG) was not associated with full-scale IQ (FSIQ). However, when the data were analyzed
by sex, MUFSG was associated with FSIQ in boys, but not girls. The authors cited the lack of data
on fluoride exposures or consumption during infancy and childhood as a limitation.323
• Ibarluzea et al. (2022): This study examined mother-child dyads from the Infancia y Medio
Ambiente (Childhood and Environmen) birth cohort project in Spain. Researchers replicated the
Canadian mother-child dyad studies but reported completely opposite results. The study found
that maternal urinary fluoride across the pregnancy was associated with significantly increased
McCarthy scores in boys for the verbal, performance, numeric, and memory domains and
General Cognitive Index, but was not significantly associated for girls.324
• Dewey et al. 2023: This prospective ecological cohort study found no association between fluoride
exposure and FSIQ in preschool children in Alberta, Canada. However, exposure to fluoridated drinking
water throughout pregnancy was associated with poorer performance on the Gift Delay test.325
• Do et al. 2023: This study of schoolchildren in Australia found that exposure to fluoridated
water during the first 5 years of life was not associated with altered measures of children’s
emotional or behavioral development or executive functioning.326
Figure 5: Mean IQ Scores (Fluoridated versus Non-fluoridated) (unadjusted)
by Fluoridation Status
IQ
or
Cognition
Scores
