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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Link to relevant study record(s)

Description of key information

72 h EC50 and NOEC in Pseudokirchneriella subcapitata were 46.5 and 2.8 mg/L, respectively, based on growth rate.

Key value for chemical safety assessment

EC50 for freshwater algae:
46.5 mg/L
EC10 or NOEC for freshwater algae:
2.8 mg/L

Additional information

One key endpoint is available to address the toxicity of the test material to green algae. The study, published by the Japanese Ministry of the Environment, was conducted in accordance with the standardised guideline OECD 201 under GLP conditions. The available data suggested that the study should be awarded a reliability score of 2 in accordance with the criteria for assessing data quality as set forth by Klimisch et al. (1997).

Pseudokirchneriella subcapitata (reported as Selenastrum capricornutum) was exposed to the test material for 72 hours. The results were reported together with a second experiment which was performed the following year.

Algae exposed to 2,6-xylenol for 72 hours had EC50 values of 48 and 45 mg/L and NOEC values of 4.0 and 2.0 mg/L with regard to growth rate. Algae exposed to 2,6-xylenol for 72 hours had EC50 values of 16 and 10 mg/L and NOEC values of 3.9 and 2.0 mg/L with regard to the area under the growth curve.

 

The key values selected for this endpoint were derived from the geometric mean of the results from both studies. According to the ECHA Guidance R.10 on information requirements and chemical safety assessment, data from multiple studies with equal reliability and performed with the same species for the same endpoint may harmonised by a geometric mean if no more than one order of magnitude apart.

Supporting data is provided in the form of non-guideline, non-GLP study with minimal information on methods or results was published in Marine Biology. The study was awarded a reliability score of 3 in accordance with the criteria for assessing data quality as set forth by Klimisch et al. (1997).

Agmenellum quadruplicatum, Chlorella autotrophica and Cylindrotheca sp. were exposed to the test material for 7 days in an algal lawn pad assay. In this type of assay, toxicity is manifested in the form of a zone of inhibition (no growth). Complete kill was denoted as a zone of inhibition 36 mm out from the edge of the filter pad.

Levels of 10 mg/filter pad resulted in complete zones of inhibition to all three algal strains evaluated. Concentrations as low as 1 mg/filter pad resulted in some inhibitory toxicity against Cylindrotheca sp., while concentrations of 2 mg/filter pad resulted in some inhibitory toxicity against Agmenellum quadruplicatum and Chlorella autotrophica.