EPA Re-developing Guidance for Cumulative Risk Assessments

Aerial view of green space between 7 high-rise apartment buildings

September 27, 2021

Updates to address environmental justice, multiple chemical exposures & multiple exposure pathways

In response to President Biden's Executive Order on addressing climate change and environmental justice, the U.S. Environmental Protection Agency (EPA) has resumed work this year on updated guidance for cumulative risk assessments. According to InsideEPAthe revised guidance document was peer reviewed in July 2021 and is expected to be released to the public by the end of the year.

EPA defines cumulative risk assessment as "an analysis, characterization, and possible quantification of the combined risks to health or the environment from multiple agents or stressors." Much of the historical emphasis on cumulative risk assessment has focused on the challenges of assessing risk to humans and the environment from multiple chemicals, exposures, and effects; however, the renewed effort at EPA appears to emphasize the physical and socio-economic stressors experienced by communities independently of chemical exposure, including poverty, lack of health care access, and climate change, among others. According to EPA's 2003 guidance, cumulative risk assessments address "how the risks from the various agents or stressors interact," a challenge fraught with scientific uncertainty.

While unlikely to become a regulatory requirement in the near term, early applications of cumulative risk assessments by EPA will likely pose scientific and public relations challenges to assessed facilities. For example, cumulative risk assessment could cause business interruptions resulting from evaluations of new technologies, new chemical registrations (including pesticides), siting of new facilities, natural resource management, regional strategies for achieving clean air and water, and closure plans for contaminated lands (e.g., hazardous waste sites).

The new cumulative risk assessment guidance is coming out as EPA is increasing public accessibility to facility-level emissions data through user-friendly geospatial information system (GIS) platforms that include environmental justice indices, community health metrics, and facility compliance reports, all of which will be available to inform future cumulative risk assessors and support the Biden administration's environmental justice directive.

How Exponent Can Help

For more than five decades, Exponent scientists have been at the forefront of scientific risk assessment guidance development and practice, including cumulative risk assessment and causal analysis. We have worked with the 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.