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New Approaches and Tools for the Conduct of Community-Based Cumulative Risk Assessments
Abstract
Communities are faced with challenges in identifying and prioritizing environmental issues, taking actions to reduce their exposures, and determining their effectiveness for reducing human health risks. Additional challenges include determining what scientific tools are available and most relevant, and understanding how to use those tools. Because of these challenges community groups often reach conclusions based more on risk perception with limited access to relevant exposure information. This research program will develop and apply (through collaborative case studies) exposure-related tools (e.g., models, methods, data, GIS applications) to address key science questions:
- How to systematically identify and prioritize key chemical stressors within a given community?;
- How to develop estimates of exposure to multiple stressors for individuals in epidemiologic studies?; and
- What tools can be used to assess community-level distributions of exposures for the development and evaluation of the effectiveness of risk reduction strategies?
The focus of this research program is primarily chemical stressors and the exposure component of the source to concentration to exposure to dose to human health outcomes continuum. NERL is collaborating with groups in ORD and other parts of EPA focusing on other stressors (biological and physical) and source-to-outcomes components. Information on socio-demographic factors and related risk modifying factors (e.g., disparity in health status, psychosocial stress, exposure to violence, housing characteristics, exposure to noise pollution, inadequate access to healthcare, behavior and lifestyle) needs to be incorporated to characterize cumulative human exposures and risks in the community setting. EPA (NCER) grants for extramural research (http://es.epa.gov/ncer/rfa/#CurrentStar) on the combined effects of toxic stressors and modifying factors will enable the analysis of disparate types of data involved in cumulative risk assessments.
Research to Date
A review of relevant tools was conducted to both assist communities and inform new tools. A compendium of tools can be found at http://www.epa.gov/air/care/library/ToolsCompendium.pdf and includes summary tables and related information for community risk assessment guidance documents, environmental issues for communities, web-based GIS tools for issue identification/prioritization, databases by media, and exposure models. Medina-Vera et al. (2009)* provides an overview of inexpensive, screening-level, measurement-based sampling and analysis methods for multiple chemicals. For Science Question #1, a new state-of-the-science web-based tool is being developed to assist with cumulative community exposure and risk characterizations. The Community-Focused Exposure and Risk Screening Tool (C-FERST) - slides (PDF, 28pp,1.8MB)- will be a “one-stop shopping” tool that is easy to use and transparent, but also based on best available science. The C-FERST user will be able to view a community report, for selected EPA-related environmental issues, that contains general information (e.g., fact sheets, weblinks), or more specific information (e.g., technical papers, maps) about population affected, sources, concentrations, exposures, risks, health effects, key factors, and exposure or risk reduction actions. Initial planned C-FERST issues will include benzene, radon, environmental tobacco smoke, ultraviolet radiation, diesel exhaust, childhood lead exposure, and asthma (collaborations are welcomed with other researchers working to address cumulative exposure and risk issues for the many topics of interest of interest to multiple communities). Developed in close cooperation with EPA’s coordinated community program (www.epa.gov/care) and scientific experts, and refined through case studies, C-FERST will bridge the gap between the emerging community-based cumulative risk science and actual use by community programs. Initial efforts have been made on several tools to address Science Question #2, including a multi-pollutant Exposure Model for Individuals (EMI) initially focusing on asthma. Specific details on other models, measurements, and methods tools and related potential case studies for the National Children’s Study and its Vanguard Centers are still being explored. Tools to address Science Question #3 may include the following: specific guidance for community data collection; inexpensive screening-level methods for multiple chemicals; methods to link models and measurements for characterizing emissions, concentrations, and exposures for community risk assessments; methods for continuous monitoring of multiple pollutants in communities (e.g., to identify “hot spots”); a cumulative community inhalation exposure model; and GIS tools for illustrating exposure and risk reduction scenarios.
*Medina-Vera M., Van Emon J., Melnyk L., Bradham K., Harper S., Morgan J. (2009) "An Overview of Measurement Tools Available to Communities for Conducting Exposure and Cumulative Risk Assessments." Journal of Exposure Science and Environmental Epidemiology.
Impact
The products of this research program and related efforts outside of the Agency will advance the science for cumulative risk assessments and empower communities with information so that they can make informed, cost-effective decisions to improve public health. More details can be found in Zartarian, V.G., and B. D. Schultz (2009), "The EPA’s human exposure research program for assessing cumulative risk in communities," Journal of Exposure Science and Environmental Epidemiology.