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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
Study period:
From April 24, 1990 to May 04, 1990
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Reference:
Composition 1
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
yes
Remarks:
KH2PO4 and NaHCO3 concentrations were 160 and 100 mg/L
GLP compliance:
yes
Test material information:
Composition 1
Specific details on test material used for the study:
- Lot/batch No.: G4 2892
- Physical state: Solid
- Analytical purity: >97%
Analytical monitoring:
no
Vehicle:
no
Details on test solutions:
A stock solution of 1 g/L was prepared in deionised water. Test solutions were prepared by dilution of the stock solution in OECD medium.
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
Test organisms
- Common name: Selenastrum capricornutum ATCC 22662
- Source (laboratory, culture collection): ATCC
- Age of inoculum (at test initiation): exponentially growing
- Method of cultivation: identical as during the test
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Hardness:
Standard OECD medium
Test temperature:
22.5 - 23°C
pH:
6.8 - 7.6
Dissolved oxygen:
-
Salinity:
Standard OECD medium
Nominal and measured concentrations:
Nominal: 0, 0.01, 0.02, 0.04, 0.08 and 0.16 mg/L
Details on test conditions:
The culturing apparatus was a cabinet in which the temperature was maintained between 22 and 24°C, and continuous uniform illumination was provided in the spectral range of 400 to 700 m. The light intensity is in the range of 6000 to 10000 lux which is obtained by using seven 30 W fluorescenr lamps (colour temperature of approximately 4300 K), at a distance of 0.35 m from the algal culture. The culture flasks were rotated continuously at 100 rpm to prevent sedimentation of the algae.
Reference substance (positive control):
yes
Remarks:
Potassium dichromate 99.5% purity lot H0234 JT baker
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
0.08 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Remarks on result:
other: 0.07 - 0.08 mg/L 95% confidence limits
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
0.05 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
biomass
Remarks on result:
other: 0.04 - 0.05 mg/L 95% confidence limits
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.04 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
other: growth and growth rate
Key result
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
0.047 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Results with reference substance (positive control):
The absorbance measurement data of potassium dichromate included in the report. From results, an ErC50 and EbC50 (0-72 h) of potassium
dichromate of 0.57 and 0.23 mg/L, respectively, was calculated. These values of the reference compound were in accordance with data of an international interlaboratory test showing that the test organisms have not changed significantly and that the slight modification of the mineral salts medium do not influence the result.
Reported statistics and error estimates:
The EC50 values were computed from the best fitted line (least square method) through the points given by the probit of the percentage inhibition and the logarithm of the concentration of the test substance. The EC50 value calculated with the area under the growth curve is termed EbC50 (0-72h) whereas the EC value calculated with the specific growth rate is termed ErC50. Confidence limits were computed based on Fieller's theorem. All computations were performed with a programme (Akzo programme, Algal version 1.0) using the software package SAS.
Validity criteria fulfilled:
yes
Remarks:
but no chemical analysis was performed
Conclusions:
Under the study conditions, the 72h EbC50 and ErC50 of the test substance for Selenastrum capricornutum were 0.05 and 0.08 mg a.i./L, respectively. The NOEC for the effect on algal growth and growth rate was determined to be 0.04 mg/L.
Executive summary:

A study was conducted to determine the toxicity to green algae (Selenastrum capricornutum) of the test substance according to OECD Guideline 201, in compliance with GLP. In a range-finding test, algal growth was totally inhibited at nominal test concentrations of 1, 10 and 100 mg/L. Therefore, in the main test, algae were exposed for 72 h to nominal concentrations of 0.01, 0.02, 0.04, 0.08 and 0.16 mg a.i./L. Algal cell concentrations were determined spectrophotometrically. No analytical verification of dose concentrations was conducted. All the validity criteria of the study were fulfilled. Under the study conditions, the 72 h EbC50 and ErC50 were 0.05 and 0.08 mg a.i./L, respectively. The NOEC for the effects on both biomass and growth rate was determined to be 0.04 mg/L (van Ginkel, 1990).

Description of key information

Key value for chemical safety assessment

EC50/LC50 for freshwater algae:
0.08 mg/L
EC10, LC10 or NOEC for freshwater algae:
0.04 mg/L

Additional information

A study was conducted to determine the toxicity to green algae (Selenastrum capricornutum) of the test substance according to OECD Guideline 201, in compliance with GLP. In a range-finding test, algal growth was totally inhibited at nominal test concentrations of 1, 10 and 100 mg/L. Therefore, in the main test, algae were exposed for 72 h to nominal concentrations of 0.01, 0.02, 0.04, 0.08 and 0.16 mg a.i./L. Algal cell concentrations were determined spectrophotometrically. No analytical verification of dose concentrations was conducted. All the validity criteria of the study were fulfilled. Under the study conditions, the 72 h EbC50 and ErC50 were 0.05 and 0.08 mg a.i./L, respectively. The NOEC for the effects on both biomass and growth rate was determined to be 0.04 mg/L (van Ginkel, 1990).