Registration Dossier

Diss Factsheets

Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
72h
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Report on read-across substance meets the criteria for classification as reliable without restriction according to Klimisch et al (1997)

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2011
Report date:
2011

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
yes
Remarks:
modified to differentiate the indirect effect of light absorption, as described in RCC Project 460302
GLP compliance:
yes

Test material

Constituent 1
Chemical structure
Reference substance name:
Tetrapotassium 5,5'-{ethane-1,2-diylbis[thio-1,3,4-thiadiazole-5,2-diyldiazene-2,1-diyl(5-amino-3-tert-butyl-1H-pyrazole-4,1-diyl)]}diisophthalate
EC Number:
700-616-6
Cas Number:
849608-59-9
Molecular formula:
C36H32K4N14O8S4
IUPAC Name:
Tetrapotassium 5,5'-{ethane-1,2-diylbis[thio-1,3,4-thiadiazole-5,2-diyldiazene-2,1-diyl(5-amino-3-tert-butyl-1H-pyrazole-4,1-diyl)]}diisophthalate

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
- Concentrations: 1.1, 3.7, 12, 38 and 120 mg/L
- Sampling method: 0h samples for analysis taken from excess test solutions. 72h samples from a single test replicate solution of each exposure (containing alga). All samples at 72 hours were analysed post centrifugation.

Test solutions

Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Controls: Test medium
- Test solutions: nominal concentrations of 1.1, 3.7, 12, 38 and 120 mg/L.

Test organisms

Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Strain: CCAP 278/4
- Source: laboratory cultures at Brixham Environmental Laboratory
- Age of inoculum (at test initiation): 4 days
- Method of cultivation: Grown in test media

Study design

Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h

Test conditions

Test temperature:
The hourly temperature measurements remained within 24 ± 2°C
pH:
At the start of the test the pH ranged from 7.3 to 7.4 and at the end of the test ranged from 6.7 to 6.8
Nominal and measured concentrations:
Test concentrations were culture medium control and test substance at nominal concentrations of 1.1, 3.7, 12, 38 and 120 mg/L. The overall geometric mean measured concentrations ranged from 78 to 119% of the nominal values. The concentrations of test substance were not maintained within ± 20 % of the nominal concentrations throughout the test, therefore the calculation and reporting of results is based on the geometric mean measured concentration.
Details on test conditions:
TEST SYSTEM
- Test vessel: glass beakers of 400 and 250 ml nominal capacity
- Type: closed
- Material, size, headspace, fill volume: 100ml test solution
- Initial cells density: 10500 cells/ml
- Control end cells density: 314000 cells/ml
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

OTHER TEST CONDITIONS
- Light intensity and quality: 10078 lux 'cool white' illunmination

EFFECT PARAMETERS MEASURED
- Determination of cell concentrations: electronic particle counter

TEST CONCENTRATIONS
- Test concentrations: 1.1, 3.7, 12, 38 and 120 mg/L.
Reference substance (positive control):
no

Results and discussion

Effect concentrationsopen allclose all
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.86 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks:
Exposed vessel
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 123 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks:
Exposed vessels
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
3.3 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks:
Exposed vessel
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
< 0.86 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks:
Exposed vessel
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
9.5 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks:
Exposed vessel
Remarks on result:
other: 95% CL 5.2-15 mg/L
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
0.86 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks:
Exposed vessel
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.86 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks:
Shaded vessel
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 123 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks:
Shaded vessel
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
3.3 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks:
Shaded vessel
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.86 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks:
Shaded vessel
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
7.2 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks:
Shaded vessel
Remarks on result:
other: 95% CL 4.0 - 11 mg/L
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
3.3 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks:
Shaded vessel
Details on results:
- Exponential growth in the control (for algal test): yes

- Colour differences: The growth rate inhibition was essentially the same for Exposed vessels (shaded by excess control culture medium, E) and the Shaded vessels (shaded by test substance solution, S). At the two lowest tested concentrations (0.86 and 3.3 mg/L) the S/E values were 0.42 and 0.89 but this is not considered to alter the conclusion. Therefore, at these concentrations it can be considered that the effects on growth rate can be attributed to the effects of light absorption (shading) by the coloured test substance. However, at 123 mg/L mean inhibition in the exposure vessels was considerably greater than mean inhibition in the shaded vessels indicating a toxic response.
Reported statistics and error estimates:
The data for cell counts obtained at 24, 48 and 72 hours was statistically analysed using a laboratory in-house software package, PCADA, where appropriate procedures were applied to test for significant differences (p <0.05) between the control and test concentrations. EC50 values and the associated 95% confidence intervals were determined using the US EPA program ICPIN (version 2, June 1993)

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
It is concluded that the effects on growth rate at concentrations of 100 mg/L or less of test material are due to the effects of light absorption. At 123 mg/L there is evidence that growth retardation is due to a toxic effect.