hazardous. Hazard evaluation is a probability assessment that adverse 

 ecological effects will result from environmental releases of a given con- 

 taminant. It involves a sequential and integrated approach to predict the 

 safety or hazard of the contaminant, and includes information on (1) chemi- 

 cal production, use, and disposal patterns; (2) acute and chronic toxicity; 

 (3) residue dynamics and bioconcentration; (4) environmental fate and moni- 

 toring; and (5) field studies (Figure 2). A hazard evaluation is not a one- 

 time estimate, and additional evaluations must be made as the data base ex- 

 pands. Useful assessment schemes have recently been proposed by Kimerle et 

 al. (1978), Duthie (1977), Stern and Walker (1978), and the American 

 Institute of Biological Sciences (1978). However, no scheme or procedure 

 can eliminate the need for sound scientific judgement. The evaluation, in 

 its essence, is a scientific judgement of the potential for environmental 

 effects (toxicity tests) with measured (or estimated) environmental con- 

 centrations. The degree of confidence in the evaluation is greatest with a 

 reliable estimate of environmental concentrations and with effects data 

 which includes studies on representative species under conditions simu- 

 lating those of natural aquatic environments. 



REFERENCES 



Addison, R.F. and R.P. Cote. 1973. Variation with chain length in acute 

 toxicity of alkylthydroxamic acids to salmon ( Salmo salar ) fry. Lipids 

 8:493-497. 



American Institute of Biological Sciences. 1978. Criteria and rationale 

 for decision making in aquatic hazard evaluation. j_n Estimating the 

 Hazard of Chemical Substances to Aquatic Life, ASTM STP 657, J. Cairns, 

 K.L. Dickson, and A.W. Maki, Eds., Am. Soc. Testing and Materials, pp. 

 241-273. 



Boyle, T.P. 1979a. Effects of the aquatic herbicide 2,4-D DMA on the 

 ecology of experimental ponds. Environ. Pollution (in press). 



Boyle, T.P. 1979b. Responses of experimental lentic aquatic ecosystems to 

 alterations of macrophyte communities. Proc. Efficacy and Impact of 

 Intensive Plant Harvesting in Lake Management Symposium. Institute for 

 Environmental Studies Center for Biotic Systems, Univ. of Wisconsin, 

 Madison (in press). 



Branson, D.R., G.E. Blau, H.C. Alexander, and W.B. Neely. 1975. Bioconcen- 

 tration of 2,2', 4,4'-tetrachlorobiphenyl in rainbow trout as measured 

 by an accelerated test. Trans. Am. Fish. Soc. 104: 785-792. 



Brungs, W.A., and D.I. Mount. 1978. Introduction to a discussion of the 

 use of aquatic toxicity tests for evaluation of the effects of toxic 

 substances. ln_ Estimating the Hazard of Chemical Substances to Aquatic 

 Life, ASTM STP 657, J. Cairns, K.L. Dickson, and A.W. Maki, Eds., Am. 

 Soc. Testing and Materials, pp. 15-26. 



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