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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

The purpose of this study was to determine the effect of the test item SIKA Hardener LTJ on the growth of a unicellular green algal species Raphidocelis subcapitata according to OECD guideline 201. The calculated biological endpoints are EC10 (growth rate) 0.58 mg/L, EC50 (growth rate) 1.70 mg/L, EC10 (yield) 0.27 mg/L, EC50 (yield) 0.70 mg/L, NOEC (growth rate) 0.4 mg/L and NOEC (yield) 0.1 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:
1.7 mg/L
EC10 or NOEC for freshwater algae:
0.58 mg/L

Additional information

Growth Inhibition Test of SIKA Hardener LTJ on Algae (Raphidocelis subcapitata)

The purpose of this study was to determine the effect of the test item SIKA Hardener LTJ on the growth of a unicellular green algal species Raphidocelis subcapitata (formerly known as Pseudokirchneriella subcapitata). Exponentially growing cultures of Raphidocelis subcapitata were exposed to various concentrations of the test item over several generations under defined conditions. The algal growth in relation to a control culture was determined over a fixed test period of 72 hours and thus, over several algal generations. The test method of application and the test species Raphidocelis subcapitata are recommended by the test guidelines. Based on the results of non-GLP Preliminary Range-Finding Test the following six test concentrations in a geometric series (with a spacing factor of 4) were tested: 0.1, 0.4, 1.6, 6.3, 25, 100 mg/L (loading rate). The test concentrations were prepared using the WAF method (by preparing individual WAFs). Due to the rapid hydrolysis of the test item (SIKA Hardener LTJ ) validation of suitable analytical method was not possible for the verification of test item concentration in aqueous test media. Analytical determination of the test item concentrations was not feasible, therefore biological endpoints of the test are based on the nominal test item concentrations (loading rate). Biological results are based on the nominal test item concentrations (loading rate).For the determination of the LOEC and NOEC, the calculated mean growth rates and yield at the test concentrations were tested on significant differences to the control values by Bonferroni t-Test using TOXSTAT software. The test item had a statistically significant inhibitory effect on the growth of Raphidocelis subcapitata after the exposure period of 72 hours based on the average specific growth rate in concentrations of 1.6, 6.3, 25 and 100 mg/L and based on yield in concentrations of 0.4, 1.6, 6.3, 25 and 100 mg/L (Bonferroni t-Test, 1 tailed, α=0.05) when compared to control. The ErCx and EyCx values of the test item and their confidence limits were calculated using Probit analysis by TOXSTAT software. The calculated biological endpoints are EC10 (growth rate) 0.58 mg/L, EC50 (growth rate) 1.70 mg/L, EC10 (yield) 0.27 mg/L, EC50 (yield) 0.70 mg/L, NOEC (growth rate) 0.4 mg/L and NOEC (yield) 0.1 mg/L.