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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

ECr50 Scenesdesmus subspicatus (48 hours) = 480 mg/l
NOEC Scenedesmus subspicatus (48 hours) = 97 mg/l

Key value for chemical safety assessment

EC50 for freshwater algae:
480 mg/L
EC10 or NOEC for freshwater algae:
97 mg/L

Additional information

Two guideline studies are available assessing the effects on the algal species Scenedesmus subspicatus over a test period of 72 hours. The first one was conducted with Potassium sorbate, reporting an 72 -hour EC50 value of 1223 mg/l and a 72 -hour NOEC of 221 mg/l. Both endpoints are related to the growth rate and based on analytically verified test concentrations. The second study was conducted with Sorbic acid as a surrogate for Potassium sorbate and adjustment of the pH. In this study, a 72 -hour EC50 of >42.8 mg/l and a 72 -hour NOEC of 4.3 mg/l were reported, also both related to the growth rate and based on measured values. Both studies were scored by the applicant as Klimisch 1. However, within the evaluation phase under the Biocides Product Directive 98/8/EEC, the Rapporteur Member State Germany downgrades both studies as Klimisch 3, stating that in both studies the control cultures did not show a monoton exponential growth over the 72 -hour test period. Only in the study conducted with potassium sorbate, an exponential growth of the control cultures could be observed in the period 0 to 48 hours. Therefore, the rapporteur proposed to perform the evaluation of the study for 48 -hour exposure.