Variability of Test Systems Used to Assess Ecological Effects of Chemicals

Numerous chemicals may produce toxicological effects which are ecologically important. Assessment of risk to ecological systems from chemical exposures includes the use of biological test systems to evaluate toxicity. Most biological test systems are laboratory oriented with no clear environmental relevance. To help focus the selection of test systems, we developed a series of descriptions of test system characteristics and suggested some criteria for selecting test systems to determine ecological effect (Novak et al. 1985). Another step in selection process is this evaluation of the variability of aquatic test systems using published data. Using the relative standard deviation, v, we classify variability as Low (v < 10%), Medium (10% ≥ v< 20%), High (20% ≤ v ≤30%) and Very High (>30%).