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Toxicity to aquatic algae and cyanobacteria
Administrative data
Link to relevant study record(s)
Description of key information
The toxicity to freshwater algae was determined as an EL50 of 20.5 mg/L (nominal concentration) of the test substance, referring to growth rate (GLP, OECD 201)
Key value for chemical safety assessment
- EC50 for freshwater algae:
- 20.5 mg/L
- EC10 or NOEC for freshwater algae:
- 6.25 mg/L
Additional information
The toxicity of the test item to the unicellular freshwater green alga Desmodesmus subspicatus was determined according to the principles of OECD-Guideline 201 and Commission Directive 92/69/EC Method C.3 (1992). The aim of the study was to assess the effects on growth rate and biomass production over a period of 72 h. The study was conducted under static conditions with an initial cell density of nominally 10E03 -10E04 cells/mL. A dose response test was carried out with water accommodated fractions (WAF) and 8 loading levels in a geometrical series with a dilution factor of 2, nominal: 1.56 -3.13 -6.25 -12.5 -25 - 50 -100 -200 mg/L. The preparation method has been chosen with regard to the test item properties and in accordance with the relevant OECD guidance document (2000). Three replicates were tested for the test item loadings and six replicates for the control. Microscopic evaluation of the celis at start of the incubation period revealed no morphological abnormalities. At the end the algae cells were partly agglutinated at loading level 12.5 mg/L. Environmenta conditions were determined to be within the acceptable limits. The concentrations of the test item were analysed at ail loading levels at test start and test end via LC MS/MS. All effect values are given based on the nominal loading levels.
Recovery of Alga Cells: After 72 h of exposure, 0.5 mL aliquots of the test medium (i.e. samples of exposed algal cells) from nominal test loadings 6.25 -200 mg/L and control were transferred to 10 mL untreated test medium. Algae were then allowed to grow for further 3 days under test conditions. The test item effect was observed to be reversible at these test loadings. Therefore, there is potential for recovery following exposure up to 200 mg/L.
NOEL, LOEL and EL50-Values (0-72 h) of the test item based on the nominal loading levels [mg/L]:
Inhibition of biomass growth: EbL50: 5.93 (95 % confidence interval: 5.23 - 6.73); LOEL: 6.25; NOEL: 3.13;
Rate-related inhibition: ErL50: 20.5 (95 % confidence interval: 16.6 - 25.3); LOEL: 12. 5 ; NOEL: 6.25; ( Dr. U. Noack-Laboratorien, 2005).
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