Example 1: 



• Exposure Assessment: Estimate the worst-case exposure for 

 a wide range of contaminants over a predefmed geographical 

 area. 



• Bioaccumulation Design: Estimate mean concentrations of 

 contaminants in edible tissues of a selected narrow size range 

 of individuals of the most contaminated species during the 

 season of peak contaminant concentrations. 



Example 1 represents a screening survey to evaluate the need for 

 further work. Edible portions of a limited number (e.g., 3-5) of in- 

 dividual organisms or composite samples would be analyzed for a large 

 number of compounds and the risk assessment conducted assuming 

 moderate or high (but plausible) consumption rates. The species and 

 size range selected would be the ones most likely to accumulate high 

 concentrations of contaminants. Typically, the target species for a 

 screening survey would be the largest individuals of a bottom dwelling 

 species associated with soft sediments. 



Example 2: 



• Exposure Assessment: Estimate the long-term average ex- 

 posure to each of the contaminants A, B, and C through 

 consumption of aquatic species L, M, N, and O combined from 

 harvest area Z for the average person in the exposed human 

 population. 



• Bioaccumulation Design: Estimate the mean concentrations 

 of contaminants A, B, and C in edible tissues of aquatic species 

 L, M, N, and O combined from harvest area Z over an annual 

 period. 



Example 2 illustrates a simple case involving the consumption of 

 multiple species from a single harvest location. Individual or com- 

 posite samples of each species would be analyzed separately during 

 different seasons or during a single season expected to represent the 

 annual average. If samples are analyzed separately during different 

 seasons (e.g., see discussion of Example 4 below), the mean annual 

 exposure for all species could still be calculated from the seasonal data. 

 In general, highly composited samples are not recommended because 

 information on different factors (e.g., species, seasons) that affect 

 contaminant concentrations is lost. 



Example 3: 



• Exposure Assessment: Estimate a plausible-upper-limit of 

 exposure to each of the contaminants A, B, and C through 

 consumption of aquatic species L, M, N, and O combined from 

 harvest area Z for a seasonal harvester in the exposed popula- 

 tion. 



• Bioaccumulation Design: Estimate the upper bound of the 95 

 percent confidence interval of the mean concentration for each 

 of the contaminants A, B, and C in edible tissues of aquatic 



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