181 



DONALD J. BENSON 

 having chemical structures resembling lignin whether 

 emanating from a pulp mill or other sources either man- 

 made or natural. For example, the apparent PBI response 

 in Lake Washington where there are no pulp mills frequently 

 exceeds 10 parts per million. 



Dr. J. L. McCarthy, who has been the prin- 

 cipal investigator of the pulp mill research group at the 

 University of Washington since its inception in 1944, will 

 comment briefly on the Pearl-Benson test later in this 

 Conference . 



The test tube response of spent sulfite 

 liquor to the Pearl-Benson Index test will persist long 

 after many of the materials which may have originally been 

 associated with the lignin portions are degraded. 

 Observations verifying this peraistence h-ave been docu- 

 mented and reported in the 1960 Gunter-McKee Report. 

 This same relationship has been shown to hold for other 

 pulping process effluents. Therefoice the use of the PBI 

 test for biologically related effects is severely limited 

 by a lack of specificity. Mr. Eugene P. Haydu, a research 

 biologist employed by the Weyerhaeuser Company, h<=)S just 

 completed .in assignment to the National Technical Advisory 

 Committee on Aquatic and Animal Life. This committee 

 appointed by Secretary of the Interior Udall was charged 



