1974 and in Lubinski, 1975), in order to estimate what proportion of 

 certain chemical concentrations reported by the Illinois EPA actually 

 existed in a toxic form. Seven chemicals were estimated to have made 

 the following average contributions to the toxicity of the Illinois 

 River in 1972 and 1975: hydrogen cyanide, 3.0 percent of a lethal con- 

 centration (96-hr LC50) ; un-ionized ammonia, 2.4 percent of a lethal 

 concentration; LAS detergent, 1.9 percent; fluoride, 1.0 percent; copper, 

 0.6 percent; zinc, 0.3 percent; and phenol 0.2 percent. When the average 

 toxicities contributed by each toxicant were added together, the esti- 

 mated total toxicity ranged from a low of 4.5 percent of a lethal level 

 at mile 56.0 to 16.8 percent of a lethal level at mile 119.7. 



Lubinski, et al. (1974) concluded that the toxicants normally do 

 not occur at levels high enough to cause fish in the Illinois River to 

 die. This was partially verified by field tests using caged bluegills. 

 However, hydrogen cyanide and un-ionized ammonia periodically occurred 

 at high enough concentrations (63 percent of a lethal level of un-ionized 

 ammonia, at mile 277.8; an estimated 47 percent of a lethal level of 

 hydrogen cyanide, at mile 119.7) to stress fish, although the lengths of 

 time fish were exposed to these toxicants, and hence their possible 

 lethal effects, could not be determined (Lubinski, et al. , 1974). 



Brown, et al. (1973) found that 4.38 percent of 2121 fish taken 

 from the Fox River (a tributary of the Illinois) had tumors compared to 

 1.03 percent of 4639 fish taken from an unpolluted watershed in Canada. 

 Brown, et al. (1973) felt that various organic and inorganic chemicals 

 and viruses were responsible for the greater frequency of tumors in Fox 

 River fish. 

 Pesticides 



Starrett (1971) had 14 mussels representing 7 species collected 

 from 5 locations in the Illinois River in 1966 analyzed for the presence 

 of organochlorine pesticides. In no instance did the total concentra- 

 tion of organochlorine pesticides exceed 0.0585 ppm, and the average 

 content was 0.0331 ppm. Since freshwater mussels can concentrate or- 

 ganochlorine pesticides several thousandfold from water (Bedford and 



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