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A Conceptual Framework for Evaluating the Interaction of a Chemical and Nonchemical Stressor in Human Health Risk Assessments: A Case Study for Lead and Psychosocial Stress

Segal, Deborah, Lin, Yu-Sheng, Ginsberg, Gary, Sonawane, Babasaheb
Human and ecological risk assessment 2015 v.21 no.7 pp. 1840-1868
case studies, human health, lead, neurodevelopment, psychological stress, public health, risk assessment, risk assessors, socioeconomic status, toxic substances, toxicity
Recent research has demonstrated that nonchemical stressors may alter the toxicity from chemical exposures. This may have public health implications for low socioeconomic status (SES) communities that may be disproportionately exposed to toxic chemicals and various types of community and personal stressors. Nonchemical stressors may introduce an important source of variability that needs to be considered by risk assessors. Herein, we propose a framework for determining if a chemical–nonchemical interaction exists and, if so, options for incorporating interaction information into risk assessments. We use the increasingly recognized interaction between lead and psychosocial stress to illustrate the framework. We found that lead exposure occurs disproportionately in low SES groups that also tend to face high levels of psychosocial stress; that stress and lead both affect neurodevelopment and that this occurs via similar pathways involving the hypothalamic-pituitary axis. Further, several epidemiological and experimental studies have provided evidence for an interaction between lead and psychosocial stress. The implications of this interaction for risk assessment are also discussed.