Association Between Biological Lead Concentrations and Autism Spectrum Disorder (ASD) in Children: a Systematic...

Area of Science:

• Environmental Health
• Neurodevelopmental Disorders
• Toxicology

Background:

• Autism spectrum disorder (ASD) is a complex neurodevelopmental condition with increasing prevalence worldwide.
• Previous studies suggest a potential association between lead (Pb) exposure and ASD, but findings across different biological specimens remain inconclusive.

Approach:

• Conducted a systematic review and meta-analysis of case-control and cross-sectional studies published between January 2000 and February 2022.
• Searched major scientific databases: PubMed, Web of Science, Scopus, and Google Scholar.
• Utilized a random-effects model to pool standardized mean differences (Hedges' g) with 95% confidence intervals to assess Pb concentration in blood, urine, and hair.

Key Points:

• Meta-analysis revealed significantly higher blood lead levels (Hedges' g: 1.21, P=0.01) and hair lead levels (Hedges' g: 2.20, P=0.01) in children with ASD compared to controls.
• No significant difference in urinary lead levels was observed between children with ASD and controls (Hedges' g: -0.34, P=0.40).
• Publication bias was detected in hair lead studies but not in blood or urine lead studies.

Conclusions:

• Elevated lead levels in blood and hair are significantly associated with autism spectrum disorder in children.
• Urinary lead levels do not show a significant association with ASD in this meta-analysis.
• Findings highlight the importance of investigating environmental toxicant exposures, such as lead, in the etiology of ASD.