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Short-term toxicity to aquatic invertebrates

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Description of key information

Under the conditions of the test, Cutinase, PPW 21180 was not acutely toxic to Daphnia magna and thus the EC50 value could not be determined and must be above the highest exposure concentration of 235 mg TOS (total organic solids)/L equivalent to 37.4 mg aep (active enzyme protein)/L. 

Key value for chemical safety assessment

Additional information

The acute toxicity of Cutinase, PPW 21180 to Daphnia magna was assessed under static exposure conditions.

Groups of 20, first instar Daphnia, less than 24 hours old, were exposed to Cutinase, PPW 21180 dispersed in Elendt M4 medium for 48 hours at nominal concentrations of 10, 22, 46, 100 and 220 mg TOS/L. Geometric mean measured concentrations were 0.70, 1.4, 2.8, 4.6 and 235 mg TOS/L. Nominal test concentrations are based on Total Organic Solids (TOS), of which the test material contained 10.4%. Verification of test concentrations was performed based on enzyme activity. The amount of measured enzyme (ng/g) was then converted to mg TOS/L in order to calculate the achieved measured concentrations. Measured concentrations ranged from 37 – 167% of nominal at 0 hours and from below the limit of detection (<2%) – 69% of nominal at 48 hours. The reduction in enzyme activity over the 48 hour exposure period is thought to be due to digestion by the test organism. Only the highest testing concentration, 220 mg/L, had sufficient measurable enzyme activity (69%) after 48 hours exposure.

The numbers of immobilised daphnids were recorded for each test and control group after 24 and 48 hours and the following values were determined. All results are expressed in terms of geometric mean measured concentration.

No immobilisation in either the control or the test group was noted throughout the exposure period, therefore neither the no-observed effect concentration (NOEC) nor the EC50 could be calculated because these values lay above that of the highest test concentration.

48h EC50                                           > 235 mg TOS/L or > 37.4 mg active enzyme protein (aep)/L

“No-observed effect concentration”:   235 mg TOS/L or 37.4 mg aep/L