4. Environmental Aspects

4.7 Aquatic Toxicity

Following the evaluation of several acute toxicity studies with exposure periods of 72-96 hours, it has been concluded that the lowest LC50 for fish is 9 mg/l. For waterflea species exposed for 48 hours, the lowest EC50 (acute immobilisation) value that has been found is 23 mg/l. Similarly, for 72 hours exposure, the lowest IC50 (growth inhibition) for green algae has been determined at 0.72 mg/l. It should be noted that some protocols to assess the aquatic toxicity hazard require that the exposure concentration is maintained during the test and that styrene depletion from water (see Figure 7) is not being considered in determination of the exposure hazard.

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