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Table 1 Characteristics of 14 cross-sectional studies of fluoride exposure and children’s cognitive and developmental outcomes published after 2012

From: Developmental fluoride neurotoxicity: an updated review

Reference

Study location, year

No. in high-exposure group

No. in reference group

Age range (or mean), years

Fluoride exposure

Outcome measure

Results

Assessment

Mean or range (mg/L)

[96]

China, 2014

123

42

8–12

Urine

3.03 (urine, short-term); 2.33 (urine, long-term); 1.34 (urine, ref)

RSPMa

Fluoride exposure was negatively associated with children’s IQ

[97]

China, 2015

26 (moderate/severe dental fluorosis)

8 (normal/questionable dental fluorosis)

6–8

Drinking water, urine

2.66 (water, moderate/severe); 1.0 (water, normal/questionable); 2.44 (urine, moderate/severe); 0.45 (urine, normal/questionable)

WRAMLb; WISC-IVc

Moderate and severe fluorosis were significantly associated with deficits in digit span scores.

[98]

India, 2015

215

214

6–12

Drinking water

2.41 (water, high); 0.19 (water, ref)

RCPMd

IQs of highly exposed children were significantly lower than those with low-level exposure

[99]

China, 2015

84

96

7–13

Drinking water, urine

1.40 (water, high); 0.63 (water, ref); 2.40 (urine, high); 1.10 (urine, ref)

CRT-RCe

Fluoride exposure was negatively associated with children’s IQ

[100]

India, 2016

23 (severe dental fluorosis)

4 (normal dental fluorosis)

6–18

Groundwater and urine

2.11 (water); 0.45–17.00 (range, urine)

CRT-RCe

IQ was negatively correlated with degree of dental fluorosis

[101]

China, 2017

68

50

3–12 months

Coal burning vs. control

Mothers in exposed group had dental fluorosis

MDI & PDI (CDCC)f

MDI & PDI in exposed group were significantly lower than those in the control group

[102]

China, 2017

167

120

8–12

Coal burning vs. control

Dental fluorosis index 53.9% in exposed group

RSPMa

IQ was lower in children with high fluoride exposure (not significant)

[103]

China, 2018

221

100

8–12

Drinking water

1.2 (water, high); 0.25 and 0.78 (water, controls)

CRT-RCe

IQ was lower in children from endemic areas and in those with dental fluorosis

[104]

Sudan, 2018

775 (total)

N/a

6–14

Drinking water

0.01–2.07 (water)

School performance based on method adopted by MoE

Inverse relationship between fluoride in drinking water and average school performance

[105]

China, 2018

134

134

8–12

Dental fluorosis

N/a

CRT-RCe

IQ was lower in children from endemic areas

[106]

Egypt, 2018

186

814

4.6–11

Drinking water

0.92–3.75 (water)

DAPg

Decreased scores in children from areas with elevated fluoride in drinking water

[107]

China, 2018

1250

1636

7–13

Drinking water and urine

2.00 + 0.75 (water, high); 1.37 + 1.08 (urine, high); 0.50 + 0.27 (water, ref); 0.41 + 0.49 (urine, ref)

CRT-RC2e

IQ was lower in children at higher fluoride in water and urine and at greater severity of dental fluorosis

[108]

China, 2019

25

27

8–12

Drinking water

N/a

CRT-RC2e

IQ was lower at elevated fluoride exposure

[109]

China, 2020

571 (total)

N/a

7–13

Drinking water, urine

1.39 + 1.01 (water); 1.28 + 1.30 (urine)

CRT-RC2e

Low to moderate fluoride exposure is associated with alterations in thyroid function and lower IQ

  1. aRaven’s Standardized Progressive Matrices; bWide Range Assessment of Memory and Learning; cWechsler Intelligence Scale for Children-Revised; dRaven’s Colored Progressive Matrices; eCombined Raven’s Test-The Rural in China; fmental development index & psychomotor development index (assessed using the Standardized Scale for the Intelligence of Children formulated by the Children Development Center of China; gDAP, Draw-A-Person