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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

In the key study, a static test according to OECD Test Guideline 201 with Pseudokirchneriella subcapitata carried out in compliance with GLP, the NOEC for HHCB was found to be 0.201 mg/l.

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:
0.201 mg/L

Additional information

The toxicity to algae was studied in a static test according to OECD Test Guideline 201 with Pseudokirchneriella subcapitata (Van Dijk, 1997). Concentrations were measured at the start and end of the test. Maintenance of the concentrations proved to be difficult and in some cases pH-values rose to above 10 indicating an insufficient buffering capacity of the medium. The loss of test material in the algal test was studied for a related polycyclic musk and it was shown that sorption to algal cells was the most relevant ‘sink’, whereas sorption to glass might play a role as well as volatilisation. The results were expressed as the mean concentration over the exposure time. Both biomass production and growth rate were not significantly inhibited up to and including 0.201 mg/l. Growth rate was inhibited by 9 and 20% (both statistically significant) at 0.466 and 0.854 mg/l. The NOEC was 0.201 mg/l (-9%). The inhibition based on Area Under the Curve was 35% and 56% at the highest two concentrations. The test was carried out under GLP and the vality criteria on the performance of the test material was fulfilled. The pH deviation was slightly more than allowed but can be explained by the high cell density reached at the end of the test.

In a supporting study, the acute toxicity of HHCB towards Pseudokirchneriella subcapitata was investigated according to OECD guideline 201. The 72h-EC50 and 72h-NOEC were found to be >0.7 mg/l and 0.23 mg/l respectively, based on measured concentrations.

As the lowest NOEC was found in the study by Van Dijk (1997) this study was chosen as the key study.