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QUESTION: 



In your testimony, you stated that the Science Advisory Board is periodically 

 updating its criteria to keep pace with advancing science. Does this mean 

 that sediment formerly deemed "clean" is now designated as contaminated 

 as our ability to detect contaminants grows? 



Does EPA feel that the ability to manage or treat contaminated sediment has 

 kept up with contaminant detection technology? 



ANSWER: 



The Administrator of EPA has established a Science Advisory Board (SAB), 

 made up of individuals from the public and private sectors, to independently 

 review scientific results which may form the basis of Agency policy. The 

 SAB does not itself develop agency policy or procedures, such as the 

 sediment quality criteria. The testimony referred to the Agency's process 

 for developing sediment quality criteria, which has included, and will 

 continue to include, review by the SAB. 



Notwithstanding the above clarification of the role of the SAB, EPA will 

 periodically review and update, as appropriate, the sediment quality criteria 

 to keep pace with advancing science. This is consistent with our process 

 for use of water quality criteria and biological-effects tests in the ocean 

 dumping program. The result of such reviews may be that some sediments 

 will be found to be contaminated which were previously thought to be clean; 

 or, sediments once thought contaminated deemed clean. It is important to 

 note that these consequences are not due merely to our improved ability to 

 detect the presence of contaminants but also result from our improved 

 ability to detect and understand the effects of contaminants. 



Improved analytical chemical methods have significantly lowered the 

 detection limits of many toxics present in sediment. This has allowed EPA 

 and other regulatory agencies to detect the presence of many sediment 

 contaminants at levels below human health or ecological effects thresholds. 

 However, for some extremely potent sediment contaminants such as dioxin, 

 effects may occur near or sometimes even below the limits of detection. 

 Since the reliability of chemical measurement generally decreases near the 

 limits of detection, it is often difficult to regulate contaminants measured at 

 levels near the detection limit. This situation is further complicated because 

 the application of new treatment technologies like bioremediation to dioxin 

 contaminated sediments will require much more highly engineered systems 



