Registration Dossier
Registration Dossier
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EC number: - | CAS number: -
Toxicity to aquatic algae and cyanobacteria
Administrative data
Link to relevant study record(s)
Description of key information
The toxicity of the test item to the unicellular freshwater green alga Raphidocelis subcapitata was determined according to the principles of OECD 201.
The aim of the study was the determination of the effects on growth rate and yield over a period of 72 hours.
The study was conducted under static conditions with an initial cell density of 7 × 104cells/mL. Five concentrations were tested in a geometrical series with a spacing factor of 3.2 in the concentration range of 0.2– 25 mg/L test item. A stock solution was prepared by adding 55.5 mg test item (including a factor of 1.11 to take into account the dilution caused by addition of the algal inoculum) to 2000 mL test medium.
This stock solution was used as highest test item concentration in the test. The further test item concentrations were prepared by diluting the stock solution with test medium.
Three replicates were tested for each test item concentration and six replicates for the control. The environmental conditions were within the acceptable limits.
The measured concentrations in the test solutions at the start of the exposure were in the range of 88.9 to 114.3% of the nominal concentrations. At the end of exposure after 72 hours, the measured concentrations in the test item solutions were in the range of 90.6 to 102.1% of the nominal test item concentrations. As the concentrations remain in the range of ± 20% of the nominal concentrations, all effect values given are based on the nominal test item concentrations.
The EC50-values of the test item on the freshwater green alga Raphidocelis subcapitata based on nominal test item concentrations after 72 hours were 5.919 (3.542 – 9.762) mg/L and 1.189 (0.502 – 2.833) mg/L, for inhibition of growth rate and yield (EyC50), respectively. The NOEC -values for growth rate and yield inhibition were 0.2.
Key value for chemical safety assessment
- EC50 for freshwater algae:
- 5.919 mg/L
- EC10 or NOEC for freshwater algae:
- 0.533 mg/L
Additional information
EC10 (72h) = 0.533 mg/L
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