EC50 tests

For the sample search on aquatic toxicity of atrazine, 1459 results were found. An excerpt on the daphnia acute aquatic toxicity tests (EC50. LC.50) is prc.scnted in Figure 5-33. 

Monobutyltirr. Four acute toxicity studies were identified for monobutyltin chloride. The critical study was an acute EC50, based on immobilization, for Daphnia magna at a concentration of 25 mg/1. All four tests were acute, and, in the absence of long-term tests, it was decided to apply an uncertainty factor of 1000. 

Acute toxicity In vitro Mammalian systems Aquatic vertebrates and invertebrates Plants IC/EC50 in appropriate test species Use of appropriate indicators of acute toxicity, for example, EPA guidance values, reference doses, and so on... 

These experimental toxicity values were compared with the theoretical toxicity units calculated for each sample and organism from the pesticide concentrations measured in the samples and their toxicity (50% effective concentration, EC50) towards the corresponding test organisms [12]. This comparison, which is illustrated in Fig. 6, gives an estimation of the extent to which the pesticides measured contribute to the observed experimental toxicity as well as about their relative contribution to it. 

The selection of suitable single species and protocols is not a trivial task and may be dependent on various factors. Some of these include simplicity, low cost, or modest material and equipment demand. However, a higher sensitivity than other species to toxicants may be decisive in this choice in order to serve as warning systems. Table 1 shows the sensitivity in terms of effective concentration (EC50), which is the toxicity endpoint for the organisms (bacteria, crustaceans, algae, and fish) selected for the toxicity bioassays. These toxicity bioassays are usually classified according to the test species involved. 

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