assumed that any statistically significant bioaccumulation relative to animals not in 

 dredged material but living in material of similar sedimentological character, is 

 potentially undesirable" (U.S. Environmental Protection Agency/Corps of Engi- 

 neers, 1977). The manual further recommends "the environmentally protective 

 approach of assuming that any statistically significant differences in tissue concen- 

 trations between control and exposed organisms are a potential cause for concern." 

 However, noting that at present "tissue concentrations of most constituents in most 

 species cannot be quantitatively related to biological effects," the manual calls upon 

 the Environmental Protection Agency and the Corps of Engineers to "objectively 

 consider the magnitude of bioaccumulation shown, the toxicological significance of 

 the material bioaccumulated, the proportion of sediment sampling sites which 

 produce uptake, the number of different constituents bioaccumulated from the sedi- 

 ments in question, the position in the human and nonhuman food webs of the species 

 showing uptake, the presence of motile species at the site which might serve as trans- 

 portation vectors removing bioaccumulated materials from the disposal area, and 

 other factors relative to the particular operation in question." 



In a January 9, 1979, letter to the New York District of the Corps of Engineers, 

 Environmental Protection Agency Region II adopted the following position on 

 interpretation of bioaccumulation test results: "In view of existing FDA criteria 

 limiting the parameters to be tested in the bioaccumulation studies and thereby 

 identifying them as potential threats to public health and welfare, and consistent 

 with the intent of Section 226.6 [c] of the regulations and the COE EPA Manual, 

 paragraph G32, any statistically significant bioaccumulation would be considered 

 cause for denial, unless such.statistically significant difference is shown to have no 

 significant adverse effect on public health and welfare." 



Early in 1980, the Corps of Engineers and Environmental Protection Agency 

 formed a joint task force that was charged with preparing a matrix for developing 

 more interpretive guidelines to evaluate the PCB problem. Meanwhile, the various 

 dredging permits concerned were being held in abeyance. The task force developed 

 an interpretive matrix under which dredged materials could be considered for 

 approval for ocean dumping if a statistically significant increase of PCB concentra- 

 tions occurred in a bioaccumulation test. This bioaccumulation test used three 

 organisms: a worm, a clam, and a shrimp. If statistically significant increases occur in 

 all three test organisms, then the material is not in compliance with the criteria and, 

 therefore, cannot be ocean dumped. If a statistically significant increase occurs in at 

 most two of the test organisms, the material is considered in compliance with the 

 criteria and can be ocean dumped without constraint, provided that the level of bio- 

 accumulation (final tissue concentration observed) in both of the organisms showing 

 statistically significant increase is below specified threshold values. If a statistically 

 significant increase occurs in at most two of the test organisms and the magnitude of 

 the uptake exceeds these threshold values, the material is considered to be unsuitable 

 for unconstrained ocean dumping. On a case by case basis, the acceptability of ocean 

 dumping this material under certain circumstances (for example, when it is capped 

 by clean material) remains open. 



This rather complex matrix is an expression of the difficulty in interpreting bio- 

 accumulation data, because information concerning the ecological significance of 

 bioaccumulation of toxic components in laboratory organisms is scarce. This is a 

 limitation inherent in applying any laboratory bioassay or bioaccumulation test to 

 the determination of the potential for environmental impact. While the development 

 and use of such laboratory tests is less expensive than field data collection and anal- 

 ysis, the use of such tests alone, as exemplified by the dredged material problem, is 

 often unsatisfactory and leads to poor decision making. 



At present the dumping of dredged material in the ocean is still controlled by- 

 criteria requiring bioaccumulation tests and a matrix approach to interpreting the 

 results of those tests. The Environmental Protection Agency and the Corps of Engi- 

 neers have stated that this matrix is only to be used on an interim basis and that 



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