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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:
1997
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study without detailed documentation
Qualifier:
according to guideline
Guideline:
EU Method C.3 (Algal Inhibition test)
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
IDENTIFICATION AND QUANTIFICATION OF TEST SUBSTANCE/PRODUCT
- Detection method (e.g. ECD, UV, MS, ICP-AES, ICP-MS): TOC-infraredanalysator
Vehicle:
no
Details on test solutions:
stock solution 1 g/L in VE-water
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Common name: Green algae
- Strain: Scenedesmus subspicatus (CHODAT (86.81 SAG))
- Source (laboratory, culture collection): Institut für Wasser-, Boden- und Lufthygiene, Berlin; subsequently in-house breeding
- Method of cultivation: in sterile-aerated Erlenmeyer flasks on light benches


ACCLIMATION
- Acclimation period: A preculture is withdrawn from a stock culture by tranfer 3 days prior to the beginning of the test from which preculture the test cultures are inoculated at a cell density of approximately 20 000 cells/mL.
- Culturing media and conditions (same as test or not): not mentioned
- Any deformed or abnormal cells observed: not mentioned
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Post exposure observation period:
none
Hardness:
Growth/test medium chemistry as described in guideline 92/69/EEC (C.3.), no further details mentioned
Test temperature:
23.4 - 23.8 °C
pH:
initiation of the test: 7.9 - 8
end of the test: 8.1 - 9.4
Dissolved oxygen:
not mentioned
Nominal and measured concentrations:
Nominal: 2; 9.9; 98.6; 986 mg/L
measured: 1. meaurement: 1.2; 9.9; 70; 738 mg/L; 2. measurement: 6.3; 12.5; 88; 951 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: sterile-aerated Erlenmeyes flasks
- Initial cells density: 2x10E4 cells/mL
- Control end cells density: 127 x10E4 cells/mL
- No. of vessels per concentration (replicates): 5
- No. of vessels per control (replicates): 8
- No. of vessels per vehicle control (replicates): not applicable


GROWTH MEDIUM
- Standard medium used: yes


TEST MEDIUM / WATER PARAMETERS
no details mentioned


OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: not adjusted
- Photoperiod: not specified
- Light intensity and quality: approx. 8000 lux, white


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Cell numbers for exposure times of 24, 48, 72 h
- Determination of cell concentrations: The cell numbers were determined photometrically at a wavelenght of 685 nm
- Chlorophyll measurement: no
- Other: none


TEST CONCENTRATIONS
- Spacing factor for test concentrations: not mentioned
- Range finding study: not mentioned
Reference substance (positive control):
no
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
5.9 mg/L
Basis for effect:
biomass
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 11.7 mg/L
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
7.8 mg/L
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
6.1 mg/L
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
10 mg/L
Basis for effect:
biomass
Details on results:
- Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test): no observations made
- Any stimulation of growth found in any treatment: no
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: no
- Effect concentrations exceeding solubility of substance in test medium: yes

Effective concentrations on the basis of cell growth:
EbC50 (72 h) = 10 mg/L
EbC10 (72 h) = 6.1 mg/L
EbC90 (72 h) = not mentioned
Effective concentrations based on the specific growth rate µ:
ErC50 (0-72 h) = > 11.7 mg/L
ErC10 (0-72 h) = 7.8 mg/L
ErC90 (0-72 h) = not mentioned
Results with reference substance (positive control):
no reference substance tested
Reported statistics and error estimates:
no statistical evaluation performed

Table 1: Cell density data:

 concentration

[mg/mL]

 cell number (x 10E4 cells/mL) after        
  0 h   24 h  48 h  72 h
 control  2 41  127 
 0.18  2 40  134 
 0.37  2 9 39  135 
0.73   2 9 40  131 
1.46   2 10  37  119 
2.93   2  10 38  135
5.86   2  11 32  122
 11.7  2  -5 26  50

                                                                         

Table 2: Growth curves:

concentration [mg/mL]   biomass (area under the growth curve) inhibition of biomass [%]   growth rate µ (0 - 72 h)  inhibition of growth rate [%]
 control 108.5  - 1.384 -
0.18 111 - 2.3 1.402 - 1.3
0.37 110.5 - 1.8 1.404 - 1.4
0.73 109.5 - 0.9 1.394 - 0.7
1.46 101.5 6.5 1.362 1.6
2.93 110.5 - 1.8 1.404 -1.4
5.86 99 8.8 1.37 1
11.7 41 62.2 1.073  22.5
Validity criteria fulfilled:
yes
Executive summary:

The acute toxicity of Marlowet 4753 (Coconut oil, reaction products with polyethylene glycol and trimethylolpropane) to aquatic algae Scenedesmus subspicatus was investigated in a static test according to 92/69/EEC.

On the basis of growth rate, a mean effective concentration ErC50 (72 h) was greater than the highest tested concentration of 11.7 mg/L. The NOEC based on biomass was 5.9 mg/L, the EC10 of the study based on growth rate was 7.8 mg/L. The substance was not soluble in test medium (synthetic fresh water). The concentrations were tested as emulsions, generating fine drops down to a dilution of approx. 2 mg/L.

Description of key information

The acute toxicity of Marlowet 4753 (Coconut oil, reaction products with polyethylene glycol and trimethylolpropane) to aquatic algae Scenedesmus subspicatus was investigated in a static test according to 92/69/EEC.

On the basis of growth rate, a mean effective concentration ErC50 (72 h) was greater than the highest tested concentration of 11.7 mg/L. The NOEC based on biomass was 5.9 mg/L, the EC10 of the study based on growth rate was 7.8 mg/L. The substance was not soluble in test medium (synthetic fresh water). The concentrations were tested as emulsions, generating fine drops down to a dilution of approx. 2 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:
11.7 mg/L
EC10 or NOEC for freshwater algae:
5.9 mg/L

Additional information