Social adversity, blood lead level, and behavior problems in young US adolescents

Abstract

Background: To investigate the associations among social adversity, very low blood lead levels (BLL; <2.5 ug/g), and behavioral problems in young adolescents from the Philadelphia community, and explore the mediating/moderating roles of lead exposure among the relationships.Methods: This cross-sectional study included 141 young adolescents aged 11 to 12 years from Philadelphia. BLLs were assessed using a graphite furnace atomic absorption spectrophotometer, and social adversity was measured using the Social Adversity Index with 18 indicators. Behavior problems, including internalizing and externalizing, were assessed with the self-reported Aggression Questionnaire, the parent-reported Conduct and Oppositional Defiant Disorder (CODD), and the parent-reported Child Behavior Checklist (CBCL). Results: The mean (SD) BLL was 2.14 (4.98) μg/dL. For externalizing behavior, BLLs were positively associated with physical aggression (r = .247, p < .01), anger (r = .257, p < .01), and total aggression score (r = .178, p < .05) from the Aggression Questionnaire after controlling for gender and ethnicity, as well as the Conduct Disorder subscale (r = .224, p < .01) and total score of Conduct and Defiant disorder (r = .184, p < .05) from the CODD Questionnaire. BLLs partially mediated the social adversity-externalizing behavior relationship, explaining 9.0, 10.1, and 17.7 percent of the effect of social adversity on physical aggression, anger, and total aggression score, respectively. For internalizing behavior, BLLs were positively related to CBCL traumatic stress (r = .179, p < .05). Social adversity moderated the lead-behavior relationship, explaining 11.1 percent of the effect of BLLs on children’s affective problems. Conclusion: Social adversity is implicated in the relationship between BLLs and behavior problems, which highlights the importance of social determinants of health. As such, early mitigation of adverse social indicators and close monitoring of BLLs may help reduce the likelihood of externalizing behavioral problems, a risk factor for future violence.