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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

OECD guideline 201, GLP, key study, validity 2:

Algal growth inhibition: NOEC= 100 mg/L

ECr50 (72h) 100 mg/L

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:
100 mg/L

Additional information

In an algal growth inhibition study performed according to OECD Guideline 201/ EU method C.3 and in compliance with GLP,Scenedesmus subspicatus(CCAP 276/20)was exposed to an aqueous dispersion of the test material at a concentration of 100 mg/L (six replicate flasks) for 72 hours, under constant illumination and shaking at a temperature of 24 ± 1 °C.Samples of the algal populations were removed daily and cell concentrations determined for each control and treatment group, using a haemocytometer and light microscope.


All test and control cultures were inspected microscopically at 72 hours. There were no abnormalities detected in any of the control or test cultures. At the start of the test all control cultures were observed to be clear colourless solutions whilst all the test cultures were observed to be very slightly cloudy white homogenous dispersions. After the 72 hour test period all control cultures were observed to be pale green dispersions whilst the test cultures were observed to be green dispersions with a slight foam at the media surface.


Mean cell density of control at 0 hours: 1.06 X 104cells per ml

Mean cell density of control at 72 hours: 7.73 x 105cells per ml


Neither the growth (r) or the biomass (b) ofScenedesmus subspicatuswere affected by the presence of the test material over the 72-hour exposure period.Exposure ofScenedesmus subspicatusto the test material gaveEbC50(72 h): > 100 mg/L; ErC50(0 - 72 h): > 100 mg/Land correspondingly the No Observed Effect Concentration was 100 mg/L.

It was considered unnecessary and unrealistic to test at concentrations in excess of 100 mg/L.


Under the test conditions, the 72 -hourErC50was > 100 mg/Land the NOEC was100 mg/L.