Al 



A. Tetrachlorophenol was the most toxic of the compoimds 

 tested followed by tetrachlorocatechol, dichlorophenol and 

 dichlorocatochcl in descending order of toxicity. 



5. Sublethal concentrations of di- and tetrachlorocatechol. 

 caused an increase in respiration rate which suggested that these 

 toxicants were uncouplers of oxidative phosphorylation. Respiration 

 rates of sockeye salmon alevins, and possibly fry, were increased 



at tetrachlorocatechol concentrations ranging from 10 to 25 per cent 

 of the 96-hr TL . Respiration rates of young pinl-c salmon were 

 increased at tetrachlorocatechol concentrations of approximately 

 4.6 to 48 per cent of the 96-hr TL . 



6. Generalized comparisons indicated that di- and 

 tetrachlorocatechol and di- and tetrachlorophenol were much less 

 toxic than insecticides such as Dieldrin, were more toxic than 

 catechol and phenol, and of the same order of magnitude as 

 pentachlorophenol . 



7. Tetrachlorocatechol was apparently oxidized by biological 

 treatment with activated sludge and it was presumed that other 

 chlorinated catechols and phenols (except pentachlorophenol) would 

 be oxidized as well, if present in bleach waste. 



8. Due to possible synergistic effects it is recommended 

 that consideration be given to the toxicity of combinations of 

 chlorinated catechols, phenols and other toxic substances when 

 examining a possible pollution problem. 



