Community-Based Cumulative Impact Assessment: California’s Approach to Integrating Nonchemical Stressors into Environmental Assessment Practices

Abstract

Risk assessment is complex and challenges assessors to expand its utility and bridge data gaps to better account for human health risk. Mixtures complicate the assessment landscape because cumulative chemical exposures occur at the nexus of nonchemical stressors that can influence adverse health outcomes. Traditional risk assessment approaches typically use comprehensive data sources and quantitative methods but have a limited capacity to account for or include nonchemical stressors. In contrast, community-based cumulative impact assessments utilize different types of data and apply both quantitative and semiquantitative methods. Recently, multiple approaches for cumulative impact assessment have been developed. One such example is the California Communities Environmental Health Screening Tool: CalEnviroScreen. CalEnviroScreen has been successful in evaluating the cumulative pollution burden at a census tract scale across the state, based on 12 pollution indicators. It also characterizes population vulnerabilities at the same scale, based on intrinsic and extrinsic factors (three health and four socioeconomic status indicators). The two indices are combined in a way that allows one to screen and identify communities across California at above or below various thresholds in the scale. CalEnviroScreen allows one to understand the similarities and differences between the most disadvantaged communities having similar scores. CalEnviroScreen has been instrumental in (a) identifying the disadvantaged communities across California that receive prioritized funding from Greenhouse Gas Reduction Funds derived from the cap-and-trade program, (b) prioritizing areas for targeted multimedia enforcement action, and (c) assisting California Environmental Protection Agency boards and departments with planning community engagement and outreach efforts.