Selection of end-points

Typically, selection of the major test end-point to be used in the investigation is based on the compliance needs or the objective of the investigation. For acute exposures, survival is often the end-point selected for performance of the toxicity assessment. Although chronic exposures often use survival, growth expressed as dry weight, or some measure of reproductive potential (i.e. fecundity, offspring production) is the major test end-point. Survival of the test organisms (expressed 

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Problem formulation a qualitative evaluation of contaminant release, migration and fate identification of contaminants of concern, receptors, exposure pathways and known ecological effects of the contaminants and selection of end-points for further study. The term end-point is used to describe the expected or anticipated effect of a contaminant on an ecological receptor (USEPA, 1989c). 

Determination of Meter Readings for the Nonaqueous Btqfer Solutions Corresponding to Acid End Points—To ensure comparable selection of end points when definite inflection points are not obtained in the titration curve, determine daily, for each electrode pair, the meter readings obtained with freshly prepared nonaqueous acidic and basic buffer solutions. 

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