33 



A 0.2 ppin concentration of dichlorocatechol caused no 



mortalities of sockeye alevins or frj'- during extended exposure. 



This concentration was less than one tenth of tlio 96-hr TL for 



m 



dichlorocatechol . 



The results indicated that a 31-day exposure did not cause 

 mortality at significantly loi/or concentrations of di- and 

 tetrachlorocatechol than did 96-hr exposure. However, it may not 

 be possible to extrapolate these results to cover exposure to 

 chlorinated catechols during the one year r^^aring period of sockeye 

 in fresh water. The possibility of additional mortalities would 

 depend upon several factors, especially detoxification mechanisms 

 which the fish may possess, accumulation of toxicant in tissues, 

 stress, and general condition of the fish (Graham, 1959; Mount, 

 1967) . 



Relative Toxicity and Effect of Chlorine 

 and Hydroxyl Substitution 



An indication of the relative toxic strength of di- and 

 tetrachlorocatechol can be gained by comparison with acute toxicity 

 of other substances, some of which are well known, Pentachlorophenate 

 at 3 ppm was toxic to coho salmon in salt water within minutes 

 (Alderdice, 1963). Pentachlorophenate and pentachlorophenol killed 

 fathead rainnov/s at concentrations between 0.32 and 0.35 ppm and 

 silver-mouthed minnows at concentrations above 0,2^ ppm (Crandall and 

 Goodnight, 1959, Goodnight, 194-2), The 96-hr TL^'s of sockeye fry 

 to di- and tetrachlorophenol, reported herein, were 1,7 and 0,4-8, 

 respectively. Phenol v/as toxic to several species of fish in the 

 range from 10 to 20 ppm (McKct and Uolf , 1963) . Catechol 

 (pyrocatechol) was lethal to p^rch at concentrations from 5 to 12 ppm 

 (Meinck, Stoof ana Kohlschiitter, 1956: Bucksteeg, Thiele and Stoltzel, 

 1955). The 96-hr TL of piirapkinseed sunfish to the insecticide 

 Dieldrin was 0,0067 ppm (Cairns and Scheier, 1964-) . 



