EPA-Expo-Box (A Toolbox for Exposure Assessors)
- Fate & Transport
Exposure can vary across populations due to differences in age, gender, dietary preferences, occupation, cultural practices, geographical locations and settings (i.e., urban versus rural), and other behaviors, activities, or sociodemographic factors that may be associated with greater contact with environmental agents. For example, infants might experience higher exposures to certain types of contaminants than adults because of mouthing behaviors that increase the likelihood of ingesting soil or dust, while older adults may be more affected by exposures to other types of environmental agents because of physiological differences associated with age (e.g., less efficient detoxifying organ systems). Individuals living in housing near major roadways or in buildings in disrepair (e.g., with peeling paint) might have higher exposure to certain types of contaminants (e.g., lead, particulate matter, vehicle exhaust) than individuals in other settings and people that consume higher than average amounts of fish and shellfish could have higher exposure to contaminants that biomagnify in the aquatic food chain than other population groups. See the Lifestages and Populations Tool Set of EPA-Expo-Box for additional information and resources on assessing exposure to specific groups (e.g., tribes/ethnic populations, workers) and lifestages (e.g., children, older adults).
EPA’s Guidelines for Exposure Assessment (U.S. EPA, 1992) suggest that it is often helpful for risk assessors to characterize and quantify the magnitude of risk for specific highly exposed, highly sensitive, or highly susceptible subgroups within the larger population. Considering vulnerability and susceptibility in an assessment is critical to protect those populations at greatest risk when making risk management decisions.
Identifying Highly Exposed Populations
U.S. EPA’s Sociodemographic Data Used for Identifying Potentially Highly Exposed Populations (U.S. EPA, 1999b) provides guidance to help risk and exposure assessors identify and enumerate populations that may potentially experience greater contact with environmental contaminants due to unique activity patterns, preferences, behaviors and various sociodemographic
The tables below provide information to help assessors enumerate populations, based on a variety of population characteristics. The intent is to provide data for selected populations of concern in common potential exposure scenarios—not for every possible population group. In some cases, these resources can be used directly to quantify a population of interest (e.g., U.S. Census Bureau data on the number of individuals in a certain age group). In other cases, the resources can be used to help characterize potential exposure for a population in a certain category (e.g., the number or percent of homes built before 1978 might serve as a surrogate measure for estimating potential lead paint exposures).
In addition to the tools described below, the Exposure Factors Handbook: 2011 Edition (U.S. EPA, 2011a) and the Child-Specific Exposure Factors Handbook (U.S. EPA, 2008) contain information that can be used to enumerate and characterize a potentially exposed population. For example, information on the percentages of the population consuming various types of foods, or engaging in certain types of activities is provided. These data are based on national survey data (e.g., National Health and Nutrition Examination Survey, National Human Activity Pattern Survey).
Tools for estimating exposure among specific population groups (e.g., tribes/ethnic populations, workers) and lifestages (e.g., children, older adults) can be found in the Lifestages and Populations Tool Set of EPA-Expo-Box.
The tables below provide information to help assessors enumerate populations, based on a variety of population characteristics.