Making the Invisible Visible: Intervening on cumulative environmental neurodevelopmental risks using a system dynamics approach

Abstract

Background: The combined effects of multiple environmental toxicants and social stressor exposures are widely recognized as important public health problems, likely contributing to health inequities. However cumulative environmental health risk and impacts have received little attention by US policy makers at state and federal levels to develop comprehensive strategies to reduce these exposures, mitigate cumulative risks and prevent harm. An area for which the inherent limitations of current approaches to cumulative environmental health risk are well illustrated is children’s neurodevelopment which exhibits dynamic complexity, intergenerational effects and interdependent and causally linked nature of multiple factors. Systems science methods enable investigators to examine the dynamic relationships of variables at multiple levels of analysis simultaneously, while also studying the impact of the non-linear behavior of the system as a whole over time. Thus we contend that a systems approach, specifically system dynamics, may be better suited for devising policy solutions to address cumulative effects of multiple chemical, physical, biological and social environmental stressors. Methods: We convened a 2 1/2-day system dynamics workshop involving experts across multiple disciplines to formally describe the multiple interacting streams of social stressors and environmental neurotoxicants impacting children’s neurodevelopment through the use of qualitative system maps and formal system dynamics simulation models. Results: An initial system dynamics causal map was developed, incorporating feedback mechanisms relevant to diverse disciplines. Potential high leverage intervention points for reducing disparities in children’s cumulative neurotoxicant exposures and effects were identified. Workshop participants developed deeper level of understanding about the complexity of cumulative environmental health risks, increased their agreement about underlying causes, and enhanced their capabilities for integrating diverse forms of knowledge about the complex multi-level problem of cumulative chemical and nonchemical exposures. Conclusion: We conclude that this approach successfully enabled a multidisciplinary group to explore relationships in a complex dynamic system.