Longitudinal association of early childhood lead exposure and adolescent heart rate variability: influence of parental education

Abstract

Lead exposure has been shown to dysregulate physiological stress responses. However, few studies have investigated the effect of lead exposure on later heart rate variability (HRV), an indicator of a stress response, in large samples of children. Furthermore, the interaction between social environmental factors and lead exposure in childhood, which commonly co-occur, remains understudied. This study examined relationships between childhood lead exposure and early adolescent physiological stress responses at different levels of parental education. Participants were 406 children from Jintan, China. Blood lead levels (BLLs) and parental education data were collected at 3–5 years of age, and HRV outcomes assessed at 12 years via frequency domain measures (LF/HF ratio) collected during an induced stress test. Results show a significant interaction between parental education and BLLs at 3–5 years. This relationship was found to be most consistent for the interaction between BLLs and mother’s years of education for both the planning (β = 0.12, p = 0.046) and speaking (β = 0.11, p = 0.043) phase of the stress task, suggesting that increasing years of mother’s education may enhance the deleterious influence of lead exposure on the HRV frequency measure, LF/HF ratio. This research highlights the complexity in lead exposure induced outcomes.

Keywords:

• Blood lead levels
• parental education
• social environmental factor
• heart rate variability
• physiological stress
• child development

Acknowledgements and funding

The authors thankfully acknowledge the participating children and their families from Jintan City and those who set up the Jintan psychophysiology lab Anna Rudo-Hutt, Adrian Raine, and Richard Liu. We additionally thank Ryan Quinn for his assistance with the statistical analysis of this study. Funding for the cohort study was provided by the National Institute of Environment Health Sciences under Grants (R01-ES018858; K02-ES019878; K01-ES015877). Additional funding supporting the authors did not contribute to the study design or data collection, analysis, or interpretation: National Institute of Nursing Research under Grant (F31NR019527; R21 NR019047); the National Institute of Environmental Health Sciences under Grant (T32ES007062); the National Institute on Drug Abuse under Grant (R21 DA046364); National Institutes of Health under Grant (R01HD087485); the University of Pennsylvania Center of Excellence in Environmental Toxicology under Grant (P30-ES013508); the Robert Wood Johnson Foundation Future of Nursing Scholars Program; and Sigma Theta Tau International Xi Chapter.

Disclosure statement

The authors report there are no competing interests to declare.

Data availability

The data that support the findings of this study are available from the corresponding author, JL, upon reasonable request.