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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

With respect to the inhibitory effect of the test item, the 0-72 h average specific growth rates were significantly different from that of the control group in the examined concentration range of 8.11 - 102.92 mg/L (calculated and measured), therefore the NOEC was determined as 2.28 mg/L (calculated) and LOEC was determined as 8.11 mg/L (calculated). The 0-72 h areas and yield were significantly different from that of the control group in the examined concentration range of 2.28 – 102.92 mg/L (calculated and measured), therefore the NOEC was determined as 0.64 mg/L (calculated) and LOEC was determined as 2.28 mg/L (calculated).

Key value for chemical safety assessment

EC50 for freshwater algae:
9.92 mg/L
EC10 or NOEC for freshwater algae:
2.28 mg/L

Additional information

The effect of ZEH 2017 test item was assessed on algal growth using the unicellular green alga Pseudokirchneriella subcapitata (Selenastrum capricornutum), over an exposure period of 72 hours.

A significant toxic response was observed during the preliminary range-finding test, therefore five test concentrations in a geometric series with a separation factor of 3.2 and one untreated control were tested in the main experiment.

The nominal concentrations of test item used in the main experiment were: 1.0, 3.1, 9.8, 31.3 and 100 mg/L. The corresponding measured and calculated test item concentrations were: 0.64; 2.28; 8.11; 28.89 and 102.92 mg/L.

As only the two highest test item concentrations could be measured, biological results are based on the measured and calculated geometric mean concentrations (more details are given in Section 4.2.).

The test design included three replicates at each test concentration and six replicates for the untreated controls.

Statistical comparisons of biomass, average specific growth rates and yield in control and in treated groups were carried out using analysis of variance (ANOVA) and Bonferroni t-Test (a = 0.05) by TOXSTAT software.

The ErC50, EbC50 and EyC50 values of the test item and their confidence limits were calculated using Probit analysis by TOXSTAT software.

With respect to the inhibitory effect of the test item, the 0-72 h average specific growth rates were significantly different from that of the control group in the examined concentration range of 8.11 - 102.92 mg/L (calculated and measured), therefore the NOEC was determined as 2.28 mg/L (calculated) and LOEC was determined as 8.11 mg/L (calculated). The 0-72 h areas and yield were significantly different from that of the control group in the examined concentration range of 2.28 – 102.92 mg/L (calculated and measured), therefore the NOEC was determined as 0.64 mg/L (calculated) and LOEC was determined as 2.28 mg/L (calculated).

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