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 en 



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Q- ro o 

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30N3HdnOOO° 



30N3HHnOOO°o 



30N3yano30°o 



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in 



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33N3aanooo°o 



Figure 3. Percent occurrence of polychlorinated biphenyl _{PCB) residues 

 in freshwater fish, by U.S. Fish and Wildlife Service Region, 1976/77. 



108 



