Registration Dossier

Diss Factsheets

Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

Currently viewing:

Administrative data

Link to relevant study record(s)

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:
other: GLP compliant guideline study, available as unpublished report, no restrictions, fully adequate for assessment.
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
- Concentrations: 100 mg/L
- Sample storage conditions before analysis: direct analysis
Vehicle:
no
Details on test solutions:
Test sample was precisely weighed with an electronic balance and dissolved in dilution water in a closed bottle to produce 100 mg/L (nominal concentration), then stirred for 48 hours. The suspension was left to rest 1 hour prior to start of the test. The solution was collected from the middle layer for use as test solution.
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Strain: ATCC 22662
- Source (laboratory, culture collection): laboratory cultured
Test type:
semi-static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h
Test temperature:
23.2 to 23.6 ºC
pH:
At start of exposure: 7.8
End of exposure: 9.5 to 9.7
Nominal and measured concentrations:
Nominal: 100 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: 500 mL sterilised Erlenmeyer flaks
- Type (delete if not applicable): closed
- Material, size, headspace, fill volume: 600 mL
- Initial cells density: 5E3 cells/mL
- Control end cells density: 28.8E4 cells/mL after 72 hours
- No. of vessels per concentration (replicates): 6 (2 additional vessels for analytical chemistry)
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: no
- Photoperiod: continuous illumination
- Light intensity and quality: 60 to 120 µE/m2

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: counting chamber
Reference substance (positive control):
yes
Remarks:
potassium dichromate
Duration:
72 h
Dose descriptor:
EL50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
NOELR
Effect conc.:
>= 100 mg/L
Nominal / measured:
not specified
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 0.072
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: effect concentration is larger than the water solubility
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
>= 0.072 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: effect concentration is larger than the water solubility
Details on results:
- Exponential growth in the control (for algal test): yes
- Effect concentrations exceeding solubility of substance in test medium: yes

As the measured concentration at 24 hours was much lower than the measured concentration at 48 hours, it can be assumed that something was wrong with the analyses at 24 hours. This value was therefore omitted from calculating the geometric mean concentration of the test substance, resulting in a measured concentration of 0.072 mg/L during the exposure period, instead of the value of 0.0436 mg/L as given in the study report.

Validity criteria fulfilled:
yes
Conclusions:
The 72-h EC50 value and the 72-h NOEC of AC-6000 in Pseudokirchneriella subcapitata are >0.072 mg/L and ≥0.072 mg/L, respectively.
Executive summary:

In a GLP-compliant OECD 201 guideline study with Pseudokirchneriella subcapitata, algae (5E03 cells/mL, six replicates) were exposed to a nominal concentration (100 mg/L) of AC-6000 for 72 hours. The test concentration was analytically verified by GC-MS from two additional vessels prepared for analytical chemistry, and was less then 80% of nominal concentrations.

The test concentration was prepared by stirring the test solution with a target dose level of 100 mg/L for 48 hours before exposure. As the measured concentration at 24 hours was much lower than the measured concentration at 48 hours, it can be assumed that something was wrong with the analyses at 24 hours. This value was therefore omitted from calculating the geometric mean concentration of the test substance.

 

The growth inhibition rate of the test substance was -3.36%. The EL50 value is >100 mg/L, the corresponding 48-h EC50 value >0.072 mg/L. This effect concentration is larger than the water solubility.

Description of key information

The 72-h EC50 value and the 72-h NOEC of AC-6000 in Pseudokirchneriella subcapitata are >0.072 mg/L and ≥0.072 mg/L, respectively; these values will be used in the assessment.

Key value for chemical safety assessment

EC50 for freshwater algae:
0.072 mg/L
EC10 or NOEC for freshwater algae:
0.072 mg/L

Additional information

A GLP-compliant OECD 201 guideline study with Pseudokirchneriella subcapitata is available for AC-6000 (Kurume Laboratory, 2007c). Algae (5E03 cells/mL, six replicates) were exposed to a nominal concentration of 100 mg/L for 72 hours. The test concentration was analytically verified by GC-MS from two additional vessels prepared for analytical chemistry, and was less then 80% of nominal concentrations.

The test concentration was prepared by stirring the test solution with a target dose level of 100 mg/L for 48 hours before exposure. As the measured concentration at 24 hours was much lower than the measured concentration at 48 hours, it can be assumed that something was wrong with the analyses at 24 hours. This value was therefore omitted from calculating the geometric mean concentration of the test substance.

The growth inhibition rate of the test substance was -3.36%. The EL50 value is >100 mg/L, the corresponding 48-h EC50 value >0.072 mg/L. This effect concentration is larger than the water solubility.