Tier I Tier II 



No adverse bio- 

 logical effects 



Environmental 

 cone, of 

 chemical 



P 



--r 



No adverse bio- 

 logical effects 



Environmental 

 cone, of 

 chemical 



I 



Tier III 



i 



-i 



zi 



i 

 "t— -_- 



— i 



i 



figure la 



\-~ 



i 



figure lb 



Environmental 

 cone of 

 chemical 



No adverse bio- 

 logical effects 



I 



.£= 





.i—- ■ 



figure 1c 



Figure 1. Relationship of a chemical concentration that produces no adverse 

 biological effects with the actual environmental concentration of the chemical. 

 Tier I bioassays of toxicity tests are preliminary or screening tests; those 

 in Tier II are of intermediate complexity; and those in Tier III are the ex- 

 pensive long-term, sophisticated tests for sublethal responses. P indicates 

 the point in the testing program where a decision is justified. Reprinted with 

 permission from the American Fisheries Society as printed in J. Cairns Jr. 

 1978. Hazard evaluation. Fisheries 3(2): 2-4. 



166 



