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EPA-Expo-Box (A Toolbox for Exposure Assessors)

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Aquatic Biota

Exposure Scenarios

Exposure to contaminants in fish can be estimated by first defining the exposure scenario of interest. Exposure scenarios typically include information on the sources and pathways of exposure, contaminants of concern, and receptor populations. They might also describe a receptor population’s activities that may affect exposure and the timeframe over which exposure occurs.

Ingestion scenarios are intended to cover routes by which bioaccumulative chemicals might end up in the food chain. Fish ingestion is a commonly evaluated scenario; persistent bioaccumulative (lipophilic) chemicals can accumulate in fish following deposition or release to the water body and watershed and transfer to fish via diet and direct transfer from the water. For a fish ingestion scenario, concentrations of the contaminants in fish (modeled or measured) are needed to estimate exposure dose.

A member of the general population could be consuming contaminated fish although the percentage of contaminated fish consumed might be diluted if fish from a variety of sources are consumed. Other important receptor populations for fish ingestion include subsistence (e.g., Native American) fishers and recreational anglers who may be more vulnerable to exposure via intake of contaminated fish from water bodies at specific locations. These subsistence fishers might have increased vulnerability given that the fish they catch could be a primary source of food for themselves or for their families. In addition, some ethnic groups—for example, Asian anglers—are more likely to eat fish skin, cooking juices, and raw fish than other anglers making them more vulnerable to portions of the fish that can contain higher levels of contamination. Resources for assessing exposure to Native American and other ethnic populations are provided in the Lifestages and Populations Tool Set of EPA-Expo-Box.

After identifying exposure concentrations and characterizing the exposed population, it is important to define all appropriate exposure factor inputs to use to estimate potential exposures and risks, and these inputs (intake rates and other relevant patterns of behavior) can be obtained from the Exposure Factors Handbook: 2011 Edition (see Exposure Factors tab in the Indirect Estimation Module of Approaches).

The table below provides some examples of scenarios involving contaminants in fish and shellfish. The list of examples is not meant to be exhaustive; there are numerous other fish and shellfish ingestion scenarios that may be constructed based on the specific needs of the assessment. There are also numerous variations of the examples provided in the table. Additional information on exposure scenarios involving contaminated fish and shellfish may be found in the Indirect Estimation Module of the Approaches Tool Set in EPA-Expo-Box.

Examples of Exposure Scenarios Involving Fish and Shellfish Ingestion and Related
Exposure Factor Handbook: 2011 Edition Tables
Medium/Route Receptor Population Activity Pattern Data Type Exposure Period
Total finfish and shellfish ingestion General population,
per capita
Fish obtained from all sources Body weight-normalized daily intake (g/kg-day) for whole population and by age group and race
[Table 10-11]
Subchronic or chronic
Total finfish and shellfish ingestion General population, consumer-only Fish obtained from all sources Body weight-normalized daily intake (g/kg-day) for whole population and by age group and race
[Tables 10-11, 10-12]
Subchronic or chronic
Fish (general) ingestion General population,
per capita
Fish obtained from all sources Body weight-normalized daily intake (g/kg-day) for all survey respondents and by geographic location, age group, sex, race, and various sociodemographic variables
[Tables 10-11, 10-37]
Subchronic or chronic
Fish (general) ingestion General population, consumer-only Fish obtained from all sources Body weight-normalized daily intake (g/kg-day) for all survey respondents and by geographic location, age group, sex, race, and various sociodemographic variables
[Tables 10-11, 10-38]
Subchronic or chronic
Finfish ingestion Recreational marine anglers Fish that are self-caught Daily intake (g/day) for all anglers by geographic region
[Tables 10-11, 10-50]
Chronic
Finfish and shellfish ingestion Recreational marine anglers and their families Fish that are self-caught Number of fish meals and portion sizes for anglers  and their families in Lavaca, Texas
[Tables 10-11, 10-62]
Subchronic or chronic
Fish (general) ingestion Recreational freshwater anglers Fish that are self-caught Number of fish meals, daily intake (g/day), and body weight-normalized daily intake (g/kg-day) for anglers in Michigan
[Tables 10-11, 10-71]
Chronic
Selected fish species ingestion Recreational freshwater anglers Fish that are self-caught Total amount of fish consumed (g) by species for anglers in Maine in 1990
[Tables 10-11, 10-74]
Chronic
Fish (general) ingestion Native American populations, consuming and nonconsuming adults Fish that are self-caught Daily intake (g/day) for adult anglers from tribes of the Columbia River Basin
[Tables 10-11, 10-88]
Chronic
Fish (general) ingestion Native American populations, consuming and nonconsuming children ≤ 5 years Fish that are self-caught Daily intake (g/day) for the young children of anglers from tribes of the Columbia River Basin
[Tables 10-11, 10-90]
Subchronic

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Several resources are available that illustrate fish ingestion exposure scenarios.

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