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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Reference
Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
yes
Details on sampling:
The limit loading levels and the control were analytically verified via GC-MS after 0 hours (start of exposure), after 24 and 48 hours and 72 hours (end of the exposure) in replicates with and without algae. All samples were filled up to the top into the sampling vials (at least 20 mL) and closed immediately with crimp caps.
Vehicle:
no
Details on test solutions:
One water accommodated fraction (WAF) was prepared with a nominal loading of the test item of 100 mg/L. The loading level is based an the results of a preliminary range finding test (non-GLP, open system). For the loading level an appropriate amount of the test item was pipetted an to an appropriate amount of dilution water. A slow stirring procedure was applied. Gentle stirring (to avoid formation of an emulsion) was carried out with a magnetic stirrer at room temperature for 24 ± 1 hour. After a separation phase of 1 hour, the aqueous phase or WAF was removed by siphoning (from the approximate bottom of the glass flask) via a glass tube (the glass tube was insertede in the dilution water before the test item was pipetted an the surface). The resulting water accommodated fraction (WAF) was used in a limit test. The WAF was checked via laser beam (Tyndall effect) for undissolved test item (formation of an emulsion), which was negative.
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Common name: Pseudokirchneriella subcapitata
- Strain: Pseudokirchneriella subcapitata HINDAK, SAG 61.81
- Source (laboratory, culture collection): Collection of algal cultures in University of Göttingen/ Germany
Test type:
static
Water media type:
freshwater
Total exposure duration:
72 h
Hardness:
26.7 CaCO3 mg/L
Test temperature:
21 - 24°C
pH:
8.07 - 9.10
Salinity:
Alkalinity 0.8 mmol/L
Conductivity:
138 µS/cm
Nominal and measured concentrations:
100 mg/L (nominal)
Details on test conditions:
TEST SYSTEM
- Test vessel: Sterile Erlenmeyer flasks (vol. 250 ml)
- Type (delete if not applicable): closed
- No. of vessels per concentration (replicates): 6
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 24 hours/day light
- Light intensity and quality: Approximately 4440 to 8880 lux, corresponding to 60 to 120 μE*m·2*s·1


Reference substance (positive control):
yes
Remarks:
Potassium dichromate
Duration:
72 h
Dose descriptor:
EL50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EL10
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EL20
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
other: NOEL
Effect conc.:
< 100 mg/L
Nominal / measured:
nominal
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
other: LOEL
Effect conc.:
100 mg/L
Nominal / measured:
nominal
Basis for effect:
growth rate
Details on results:
The EL50-values for inhibition of growth rate (ErL50) and yield (EyL50) after 72 hours were > 100 mg/L, respectively. The NOEL-values for both inhibition of growth rate and yield after 72 hours were < 100 mg/L, respectively.
Validity criteria fulfilled:
yes
Conclusions:
The EL50-values for inhibition of growth rate (ErL50) and yield (EyL50) after 72 hours were > 100 mg/L, respectively. The NOEL-values for both inhibition of growth rate and yield after 72 hours were < 100 mg/L, respectively.

Description of key information

The toxicity of C9-11 Methacrylate to the unicellular freshwater green alga Pseudokirchneriella subcapitata was determined according to the principles of OECD 201 and Council Regulation (EC) No. 266/2016/Method C.3. The test item is a clear colorless liquid and has a very low water solubility. The study was conducted under static conditions with an initial cell density of 6839 cells/ml. A water accommodated fraction (WAF) with a nominal loading of 100 mg test item/L was prepared with dilution water 24 ± 1 hour prior to the start of the exposure. In this study, the effect values of C9-11 Methacrylate on the growth of the freshwater green alga Pseudokirchneriel/a subcapitata after 72 hours were determined as follows (based on nominal test item loadings): The EL50-values for inhibition of growth rate (ErL50) and yield (EyL50) after 72 hours were > 100 mg/L, respectively. The ErL10 -value for inhibition of growth rate was > 100 mg/L. The NOEL-values for both inhibition of growth rate and yield after 72 hours were < 100 mg/L, respectively. In this limit test with a loading of 100 mg/L a slight but statistically significant effect was observed on algae growth and yield, while no inhibition was observed with the same loading in the preliminary range-finding test. In the same range finding test slight effects on yield were observed at a lower loading of 10 mg/L. In the limit test the analytical results at the start of exposure were markedly higher than the water solubility limit of 40 ± 20 μg/L, while in the range finding test the analytical concentrations were only slightly above the water solubility limit, with a higher value in the loading 10 mg/L compared to the loading 100 mg/L. The test solutions in both tests were prepared as WAFs without a separation of the undissolved fraction. An observation of undissolved test item in concentrations < 1 mg/L by visual inspection is very difficult. In conclusion these findings indicate that the effects of the test item on algae occur above the limit of solubility of the test item in water and may be caused by undissolved components of the test item.

Key value for chemical safety assessment

Additional information