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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

On the green algae Selenastrum capricornutum (new name: Pseudokirchnerella subcapitata) a 72h-EC50 of 110.5 mg/L and a 72h-NOEC of 2.91 mg/L were obtained for o-toluidine.

Key value for chemical safety assessment

EC50 for freshwater algae:
110.5 mg/L
EC10 or NOEC for freshwater algae:
2.91 mg/L

Additional information

Following the OECD Guideline 201 (Alga, Growth Inhibition Test) a 72h-NOEC of 2.91 mg/L and a 72h-EC50 of 110.5 mg/L was received on Selenastrum capricornutum (new name: Pseudokirchnerella subcapitata). The values are based on nominal concentration as an analytical monitoring was performed and yielded in high recoveries (mean 88.8%). The toxicity was recalculated based on growth rate with cell concentrations given in the report as the time span taken for claculation of the EC50 was unclear (24 -72 h or 0 -27 h). The test was carried out in triplicate for each nominal concentration. In this study the most sensitive value on algae was revealed. In another study on Scenedesmus obliquusa 48 h-EC50 of 490 mg/l was determined.This data is also presented in OECD SIDS-dossier within the scope of the ICCA/HPV-program.

In the OECD SIDS dossier test procedure described by Bringmann and Kuehn (1959) was scored to be reliable for assessment. Toxicity to algae was assessed using effect concentration relating to biomass obtained in a study conducted to the EU-method C.2. According to the Guidance on information requirements and chemical safety assessment R.7b (ECHA, 2012) results based on the biomass should not be used for assessment since biomass results depend on the growth rate of the species as well as the test duration and other elements of the test design. Thus, the presented result was scored as not reliable.

With the same argument the study of Maas-Diepeveen (1986), as basing on yield, was scored to be not reliable.