Air pollution and heart rate variability: effect modification by chronic lead exposure

Area of Science:

• Environmental Health
• Cardiovascular Health
• Toxicology

Background:

• Outdoor air pollution and lead exposure are known to disrupt cardiac autonomic function.
• The combined effects of these exposures on cardiac autonomic function have not been previously investigated.

Purpose of the Study:

• To examine if cumulative lead exposure modifies the association between air pollution and heart rate variability.
• To assess the impact of combined environmental exposures on cardiovascular health in elderly men.

Main Methods:

• Cross-sectional analysis of 384 elderly men from the Normative Aging Study.
• Measurement of cumulative lead exposure using bone lead (tibia and patella).
• Linear regression models controlling for covariates to assess air pollution and heart rate variability associations.

Main Results:

• Higher tibia lead levels were associated with significant reductions in heart rate variability (high-frequency and low-frequency powers) in relation to ozone and sulfate exposure.
• Increased ozone and sulfate exposure showed graded decreases in heart rate variability across quartiles of tibia lead.
• Bone lead (tibia and patella) demonstrated effect modification on the relationship between air pollution and heart rate variability.

Conclusions:

• Individuals with long-term higher lead exposure may be more susceptible to cardiac autonomic dysfunction during high air pollution events.
• Environmental health research should consider both current pollution levels and historical lead exposure as critical susceptibility factors for aging populations.
• Understanding combined environmental exposures is crucial for protecting cardiovascular health in the elderly.