Blood lead (Pb) levels: a potential environmental mechanism explaining the relation between socioeconomic status and cardiovascular reactivity in children.

OBJECTIVE: A number of studies have shown an association between socioeconomic status (SES) and cardiovascular reactivity to acute stress. In addition, the authors recently reported that higher early childhood blood lead (Pb) levels are associated with significantly greater total peripheral (vascular) resistance (TPR) responses to acute stress. It is not known whether the SES-TPR association is mediated by underlying differences in blood lead levels. DESIGN: Participants were 9.5-year-old children (N=122) with established early childhood blood lead levels. MAIN OUTCOME MEASURES: Family SES was measured using the Hollingshead Index, blood lead levels were abstracted from pediatrician and state records, and children's cardiovascular responses to acute stressors were measured in the laboratory with impedance cardiography and an automated blood pressure monitor. RESULTS: Lower family SES was shown to be associated with significantly higher blood lead levels as well as significantly heightened systolic blood pressure, diastolic blood pressure, and TPR responses to acute stress tasks. A mediational analysis confirmed that Pb was a significant mediator of the SES-TPR reactivity association; some evidence also suggested moderation. CONCLUSION: These results suggest the importance of considering the chemical environment as well as social and psychological environment when evaluating cardiovascular effects of low SES.