Mercury Exposure and Heart Rate Variability: a Systematic Review

Area of Science:

• Environmental Health
• Cardiology
• Neurotoxicology

Background:

• Mercury is a neurotoxin linked to cardiac dysfunction.
• Heart rate variability (HRV) is a key indicator of cardiac autonomic function.
• The specific impact of mercury on HRV requires further elucidation.

Purpose of the Study:

• To systematically review the existing literature on mercury exposure and its association with heart rate variability.
• To define mercury's role in modulating cardiac autonomic function.

Main Methods:

• A systematic review of studies was conducted.
• Searches were performed in PubMed, Embase, TOXLINE, and DART databases.
• Findings were reported qualitatively due to study heterogeneity and limitations.

Main Results:

• Twelve studies on mercury exposure and HRV in human populations were identified.
• Prenatal methylmercury exposure showed associations with reduced parasympathetic activity markers (e.g., high-frequency HRV).
• Long-term effects on cardiac autonomic function were suggested by cord blood mercury levels in one cohort study.

Conclusions:

• Current evidence is insufficient for definitive causal inferences regarding mercury's effects on HRV.
• Further research is essential to understand mercury's impact on cardiac autonomic function, particularly concerning early-life exposures.
• Early-life mercury exposure may have lasting consequences for cardiac parasympathetic function.