Scientific Article Review:

Fluoride Exposure and Cognitive Neurodevelopment

Published In: Environmental Research
Publication Year: 2023

Study Design

This work is a systematic review and dose-response meta-analysis that examined the impact of fluoride exposure on children's cognitive neurodevelopment. The study synthesized data from 33 studies, of which 30 were included in the meta-analysis.

Funding Sources

The authors reported no specific funding from public, commercial, or not-for-profit organizations.

PICO Framework - what was studied and how?

Population:

Children aged ≤18 years from various countries, exposed to fluoride in water, food, or dental products.

Intervention:

Higher levels of fluoride exposure (≥1 mg/L in water or elevated urinary fluoride).

Comparison:

Lower fluoride exposure (≤0.7 mg/L in water or reduced urinary fluoride).

Outcomes:

Differences in intelligence quotient (IQ) scores, measured using various standardized tests.

In Paragraph Form:
This systematic review evaluated the cognitive effects of fluoride exposure in children. It compared IQ scores between high-fluoride and low-fluoride exposure groups using data from diverse sources, including water, urinary fluoride, and other biomarkers.

Inclusion and Exclusion Criteria

Inclusion Criteria:

• Studies investigating fluoride exposure via drinking water, food, dental products, or biomarkers.
• Participants aged ≤18 years.
• Measured cognitive outcomes using validated IQ tests.

Exclusion Criteria:

• Exposure to fluoride from unusual sources (e.g., volcanic activity).
• Studies limited to specific conditions like autism or ADHD.
• Studies with incomplete data on exposure or outcomes.

Demographics and Study Design

• Total Participants: 12,263 children from 7 countries, including China, India, Canada, and others.
• Designs Included: 29 cross-sectional and 4 cohort studies.
• Exposure Assessment:
  • Water fluoride: 25 studies (0.13–5.55 mg/L).
  • Urinary fluoride: 14 studies (0.16–7 mg/L).

Primary Outcome Variables and Results

• Outcome: Differences in IQ between high and low fluoride exposure groups.
• Findings:
  • IQ scores were lower in the high fluoride group.
  • For water fluoride, the IQ decrease per 1 mg/L above 1 mg/L was approximately 3.05 points (95% CI: −4.06, −2.04).
  • For urinary fluoride, the IQ decrease per 1 mg/L was 2.15 points (95% CI: −4.48, 0.18).

Conclusions

The analysis suggests a dose-dependent decline in IQ scores with increasing fluoride exposure. The effect is more pronounced in water fluoride concentrations above 1 mg/L. The findings indicate potential neurodevelopmental risks associated with fluoride levels previously considered safe (0.7–1.2 mg/L). However, the high variability in study quality highlights the need for more rigorous research.

Discussion: Strengths and Weaknesses

Strengths:

• Comprehensive dose-response analysis.
• Large participant sample from diverse regions.
• Use of standardized IQ measures.

Weaknesses:

• Most studies had cross-sectional designs, limiting causal inferences.
• High variability in risk of bias across studies.
• Few studies accounted for confounders like socioeconomic status or parental education.

Citation

Veneri F, Vinceti M, Generali L, et al. Fluoride exposure and cognitive neurodevelopment: Systematic review and dose-response meta-analysis. Environ Res. 2023;221:115239. Link to PubMed

Visual Aids

Chart: IQ Decrease by Exposure Type