species L, M, N, and O combined from harvest area Z during 

 the season of highest contamination. 



The general sampling design for the objectives of Example 3 would 

 require rephcate composite samples to estimate upper bounds of 95 

 percent confidence intervals for the mean concentrations of con- 

 taminants across species. To meet these objectives, samples could be 

 composited across species, although this is generally not recom- 

 mended. Multispecies composites would not provide data for assess- 

 ing exposures corresponding to different dietary habits. To obtain an 

 upper-limit estimate of exposure, it might be sufficient to analyze 

 samples from only one season if available information on seasonal 

 variation was sufficient to select one season as the expected worst case. 



Example 4: 



• Exposure Assessment: Estimate the probability distribution 

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

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

 harvest area Z for various segments of an exposed population 

 (e.g., ethnic groups) over an annual period. 



• Bioaccumulation Design: Estimate the probability distribu- 

 tion of concentrations of contaminants A, B, and C in edible 

 tissues of each of aquatic species L, M, N, and O from harvest 

 area Z over an annua! period. 



To accomplish the objectives of Example 4, extensive seasonal data on 

 the dietary composition of several subgroups of the exposed popula- 

 tion must be available. Separate replicate composite samples of each 

 harvested species could be analyzed for each season. During each 

 season, the species analyzed would correspond to those represented 

 to a significant extent in the diet. Probability (frequency) distributions 

 and means of contaminant concentrations would be derived for each 

 species during each season. By combining data from different species, 

 the probability distribution of exposure and the mean exposure 

 weighted by species representation in the diet could be calculated for 

 each population segment. Note that data to support the analyses 

 required by Example 4 are seldom available before a specially designed 

 study is conducted. 



Example 5: 



• Exposure Assessment: Estimate an average and a plausible- 

 upper-limit of exposure to each of the contaminants A, B, and 

 C through consumption of each of aquatic species L, M, N, and 

 O from each of the harvest areas X, Y, and Z over an annual 

 period. 



• Bioaccumulation Design: Estimate the mean concentration 

 and 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 each of species L, M, N, and O from each 

 of the harvest areas X, Y, and Z during each of the harvest 

 seasons. 



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