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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

The following study has been submitted to address the toxicity to aquatic algae and cyanobacteria endpoint:
Steger-Hartmann, T. (1999). Growth inhibition test of di-n-butyltin dilaurate (ZK 21976) on the green algae Scenedesmus subspicatus. Research Report No. IC29. Berlin, Germany. Testing laboratory: Schering AG, Experimentelle Toxikologie. Report no.: IC29. Study number: TXST19980233. Report date: 1999-02-17.
A reliability rating of 2 was assigned to this study, according to the criteria of Klimisch, 1997 as the study was conducted in accordance with generally accepted scientific principles, possibly with incomplete reporting or methodological deficiencies, which do not affect the quality of the relevant results. This study was chosen as the key study. Result: No EC50 could be determined, however nominal loading rate was 100 mg/L, so EC50 is considered to be >100 mg/L loading rate (>1 mg/L).

Key value for chemical safety assessment

EC50 for freshwater algae:
1 mg/L

Additional information

Di-n-butyltin-dilaurate had a slight inhibitory effect on the growth of Scenedesmus subspicatus at all chosen dilutions after 72 h. However, the effect showed no concentration dependence and did not exceed a 27% inhibition of the biomass integral and 16% inhibition of the growth rate. Concomitant tin analysis indicated that the calculation of the di-n-butyltin dilaurate concentration on the basis of TOC led to an overestimation in all dilutions. The tin content displayed a non-linear dilution behaviour, revealing extreme inhomogeneity of the test substance.

Due to the lack of dose-dependence the EbC50 (biomass) and the ErC50 (growth rate) could not be calculated. A NOEC value could not be established.

Since the observed inhibition was small even at the highest concentrations, it is concluded, that a saturated solution of di-n-butyltin dilaurate is not very toxic to the green algae Scenedesmus subspicatus.