Scientific Article Review:

Developmental Fluoride Neurotoxicity: An Updated Review

Published In: Environmental Health
Publication Year: 2019

Study Design

This article is a systematic review of recent cross-sectional, prospective, and retrospective studies examining the relationship between fluoride exposure and neurotoxicity, especially during early development.

Funding Sources

The study was funded by the NIEHS Superfund Research Program (P42ES027706).

PICO Framework - what was studied and how?

Population:

• Children from endemic areas with high fluoride exposure and mothers exposed to fluoride during pregnancy.

Intervention:

• Fluoride exposure through drinking water, dietary sources, and environmental contamination.

Comparison:

• Populations with lower or no fluoride exposure.

Outcomes:

• Cognitive development, measured through IQ tests and neurobehavioral assessments.

In Paragraph Form:
The review focused on children and pregnant women exposed to fluoride from water and other sources, comparing their cognitive outcomes to those in low-exposure populations. Outcomes were primarily assessed through standardized IQ tests and neurobehavioral measures.

Inclusion and Exclusion Criteria

Inclusion Criteria:

• Studies examining fluoride exposure's effect on cognitive function.
• Participants from high-fluoride areas.

Exclusion Criteria:

• Non-English articles with only abstract access.
• Studies without individual-level fluoride exposure data.

Demographics and Study Design

Overview of Study Subjects:

• Includes data from 14 cross-sectional and 5 prospective studies.
• Large samples in some studies, e.g., over 1,200 children, to small cohorts like 68 infants.

Comparison Groups:

• High fluoride exposure groups vs. low/no exposure groups.

Primary Outcome Variables and Results

Outcome: Cognitive Impact of Fluoride Exposure

1. IQ Deficits in High-Exposure Areas:

   • Children in high-exposure areas exhibited significant IQ reductions (~7 points lower on average).

2. Dose-Response Relationship:

   • For each 1 mg/L increase in maternal urinary fluoride, children’s IQ dropped by 5-6 points (p < 0.05).

3. Benchmark Dose Levels (BMDLs):

   • Safe daily intake estimated at 0.22 mg/L in drinking water.

Conclusions

The review underscores that elevated fluoride exposure during early development is significantly associated with cognitive deficits. The evidence suggests a dose-response relationship, emphasizing that even low exposure levels, such as those found in fluoridated drinking water, could pose risks.

Discussion

Strengths:

• Includes data from diverse geographical regions.
• Prospective studies provide robust individual-level exposure data.

Weaknesses:

• Some studies lacked control for confounders (e.g., iodine deficiency).
• Limited long-term follow-up to assess later-life cognitive impacts.

Citation

Grandjean P. Developmental fluoride neurotoxicity: an updated review. Environ Health. 2019;18:110. Available: PubMed

Visual Aids

Simple Chart: Cognitive Decline with Fluoride Exposure