EPA Examining Cumulative Impact Assessments

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March 15, 2022

Recent white paper identifies data gaps & recommends research to support use of cumulative impact assessment in regulatory decisions

The U.S. Environmental Protection Agency's (EPA's) Office of Research and Development (ORD) recently released a draft white paper for public comment advocating for greater attention to the cumulative impacts of human activities and the need to improve methods for cumulative impact assessment.


The draft white paper recommends research in five different policy categories and discusses the data gaps that hinder understanding of the environmental and social challenges facing disproportionately affected communities. 


Equity and environmental injustice are the central focus of ORD's call for research. The effort stems from President Biden's Executive Orders 13985 and 14008, directing the federal government to address health disparities driven by a growing number of environmental and socio-economic factors. Cumulative impact assessments are poised to be a key tool used by EPA to prioritize regulatory actions affecting business operations; however, as ORD's white paper outlines, a number of technical and policy challenges remain. As EPA moves forward to address these issues, industry will have opportunities to engage with regulators and the scientific community to ensure that the cumulative impact assessment guidance and associated applications reflect mutually agreeable objectives and technically defensible assumptions.     

ORD's research recommendations seek to leverage current knowledge to encourage new assessment tools and approaches for incorporating cumulative impact considerations into agency decisions. EPA's Science Advisory Board will review the white paper in early March, and, while further research and formal guidance are needed to apply cumulative impact assessment in practice, there is strong impetus within the U.S. federal government to move forward with demonstration projects that will likely involve regulated municipal and industrial facilities.

ORD defines cumulative impacts as "the total burden — positive, neutral, or negative — from chemical and non-chemical stressors and their interactions that affect the health,- [sic] well-being, and quality of life of an individual, community, or population at a given point in time or over a period of time." Such impacts include current and past exposures and direct and indirect effects to people "through impacts on resources and the environment that affect human health and well-being." ORD emphasizes the definition of cumulative impacts as it relates to the vulnerability or resilience of communities and populations within society. Cumulative impact assessment is a structured approach for accounting for cumulative impacts. It differs from "cumulative risk assessment," which focuses more on the environment and the consequences of exposure to multiple chemicals through various environmental media (e.g., air, water).

ORD's draft white paper identifies several research gaps and barriers to cumulative impact assessment, including stressor identification, prioritization, and characterization; methods for combining quantitative and qualitative data; and high-resolution spatial and temporal data coverage. These challenges are further amplified by the inherent variability of the types, quantities, and qualities of socio-economic and environmental data available for a given location, as well as the uncertainty in the science of evaluating impacts associated with multiple stressors in varied socioeconomic and cultural settings. These considerations, among others, affect the reliability of any conclusions drawn from a cumulative impact assessment.

Cumulative impact assessment has been identified as a means for helping federal, state, and local officials identify and address environmental injustice; however, as these assessments, along with forthcoming updated guidance on cumulative risk assessment, are developed and applied in regulatory actions, there will likely be critical scientific challenges to conclusions and recommendations resulting from the assessments. As pressure increases on federal, state, and local officials to address environmental justice and demonstrate a commitment to environmental equity, a wide range of business activities such as facility siting, site closure plans, transportation projects, pipeline routing, and waste permitting, among others, will likely be early test cases for incorporating cumulative impact assessments into regulatory decisions.

How Exponent can help

Exponent scientists are at the forefront of scientific risk assessment guidance development and practice, including the areas of cumulative risk assessment and causal analysis. We have worked with EPA on refining risk assessment guidance documentation, taught courses to risk practitioners, conducted risk assessments on complex issues including mixtures and multiple stressors on behalf of clients, provided critical review of risk assessments performed by others, and assessed the likelihood of various stressors contributing to adverse human and ecological effects. Our data-driven approach to risk and causal analysis provides robust, scientifically grounded assessments that address uncertainties, support regulatory proceedings, and inform decision-making.