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
Study period:
1997-10-17 to 1998-01-21
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
equivalent or similar to guideline
Guideline:
EU Method C.3 (Algal Inhibition test)
Version / remarks:
European Commission Directive 92/69/EEC, Part C3 of the EC Methods for the Determination of Ecotoxicit.
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
GLP compliance:
yes (incl. QA statement)
Specific details on test material used for the study:
- Name of test material (as cited in study report): JEFFCAT ZF-10
- Physical state: Clear liquid
- Lot/batch No.: 186-2-05/95
Analytical monitoring:
yes
Details on sampling:
- Concentrations: 0, 6.25, 12.5, 25, 50, and 100 mg/L (nominal)
- Sampling method: At the start of the definitive test, four 100 mL samples were taken from the additional flasks at each exposure level for analysis. After 72 hours, the contents of the replicate flasks at each exposure level were pooled and four samples (100 mL) were reserved for analysis.
- Sample storage conditions before analysis: On each sampling occasion, one sample was analysed immediately, while the other samples were stored in a refrigerator in case further analysis was required.
Vehicle:
no
Details on test solutions:
An aqueous stock preparation (1000 mg/L) was prepared by the direct addition of the test material (250 mg) to OECD medium (250 mL); the pH of the stock was adjusted from 10.6 to 8.1 using hydrochloric acid (0.8 ml; 1M) before use. A series of intermediate aqueous stock dilutions (62.5 to 500 mg/L) were prepared in OECD medium from the concentrated stock. An aliquot (10 mL) of the appropriate stock dilution was added to each of the test vessels to provide the test media.
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Common name: Green algae
- Source (laboratory, culture collection): obtained from the Culture Collection of Algae and Protozoa (CCAP), Freshwater Biological Association, Ferry House, Ambleside, Cumbria, 11 December 1997
- Method of cultivation: Algae stored in an illuminated incubator nominally at 5 °C until required. Initially, liquid cultures for the test inoculums were established by inoculation of OECD medium with cells aseptically removed from cultures. Subsequently, subculture were prepared from these liquid cultures by the aseptic transfer of aliquots into fresh OECD medium, which was then incubated for several days, until the required cell density had been achieved.

ACCLIMATION
- Culturing media and conditions (same as test or not): Cultures were prepared in OECD medium and maintained in a temperature-controlled illuminated orbital incubator, at 21 – 25 °C, at a nominal shaking speed of 150 revolutions per minute. Continuous illumination was supplied by fluorescent lights with an intensity of approximately 7698 lux (range: 7510 - 7940 lux).
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Test temperature:
21.1 to 23.8 °C
pH:
8.0 - 9.3
Nominal and measured concentrations:
Nominal test substance concentrations of 6.25, 12.5, 25, 50 and 100 mg/L. Mean measured levels of test substance were 3.93, 12.0, 29.3, 55.9 and 110 mg/L.
Details on test conditions:
TEST SYSTEM
- Test vessel: 250 ml conical flasks
- Initial cells density: 10000 cells/ml
- No. of vessels per concentration (replicates): 9 (five flasks from each test group were incubated; the others were used for temperature and pH measurements and chemical measurements at the start)
- No. of vessels per control (replicates): 10 (Six flasks from the control group were incubated; the others were used for temperature and pH measurements and chemical measurements at the start)

GROWTH MEDIUM
- Standard medium used: yes, OECD medium

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: yes

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: The number of cells in each sample was determined using an electronic particle counter. Estimates of cell numbers were based on the means of three consecutive counts.
Reference substance (positive control):
no
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
29.3 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
29.3 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
biomass
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 110 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: The specific growth rate was at most only 29%, the 50% effect concentrations (ErC50) could not be calculated but must be greater than 110 mg/L.
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
69.3 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks on result:
other: 95% confidence limits of 63.3 and 76.6 mg/L
Reported statistics and error estimates:
Growth rate of test cultures were expressed as percentages of the control (subtracted from 100). Statistical comparisons of average specific growth rates in control and test cultures were carried out using Dunnett's muticomparison test.
Biomass was calculated by determining the areas under the growth curves of the control and test cultures.
Validity criteria fulfilled:
not specified
Conclusions:
The no-observed-effect concentrations (NOECs) for both growth rate and biomass was 29.3 mg/L. Because the reduction in average specific growth rate was, at most, only 29%, the 50% effect concentration (EC50) could not be calculated but must be greater than 110 mg/L. The 50% effect concentration for mean biomass (EC50) was 69.3 mg/L.

Description of key information

Algal Growth Inhibition study of test substance was conducted similar to OECD guideline 201 following GLP.

The NOECs for both growth rate and biomass were 29.3 mg/L. Because the reduction in average specific growth rate was, at most, only 29%, the 50% effect concentration (EC50) could not be calculated but must be greater than 110 mg/L. The EC50 (72h) based on growth rate was 69.3 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:
110 mg/L
EC10 or NOEC for freshwater algae:
29.3 mg/L

Additional information