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Toxicity to aquatic algae and cyanobacteria

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Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
22 - 25 Jul 1999
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Guideline study with acceptable restrictions (no purity)
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Version / remarks:
(1984)
Qualifier:
according to
Guideline:
EU Method C.3 (Algal Inhibition test)
GLP compliance:
yes (incl. certificate)
Remarks:
The Department of Health of the Government of the United Kingdom (date of inspection 23 Mar 1998)
Analytical monitoring:
yes
Details on sampling:
- Concentrations: Water samples were taken from the control (replicates R1-R2 pooled) and the 100 mg/L loading rate WSF test group (replicates R1-R3 and R4-R6 pooled) at 0 and 72 h.
- Sample storage conditions before analysis: Duplicate samples were taken at 0 h and stored frozen (approx. -20°C) for further analysis if necessary.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: An amount of test material (2000 mg) was added to the vortex created in 20 L of culture medium to give a 100 mg/L loading rate. The mixture was stirred for 23 h with a vortex depth of approx. 25%. After stirring the mixture was allowed to stand for 1 h prior to the removal of the WSF by filtration through 0.45 µm filters. An aliquot (2000 mL) of the WSF was inoculated with algal suspension (10 mL) to give the final test concentration of 100 mg/L loading rate WSF.
- Controls: reverse osmosis purified deionised water (Elga Optima 15+) without test item
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Common name: green algae
- Strain: CCAP 276/20
- Source: Culture Centre for Algae and Protozoa (CCAP), Institute of Freshwater Ecology, Ferry House, Ambleside, Cumbria
- Method of cultivation: The culture was maintained in the laboratory at a temperature of 21 ± 1 °C under continuous light (approx. 7000 lux) and constant aeration. The culture medium was prepared according to the OECD guideline (AAP medium).
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h
Test temperature:
24 ± 1 °C
pH:
7.3-7.6 (0 h), 8.0-8.8 (control, 72 h), 8.8 - 9.7 (100 mg/L, 72 h)
Nominal and measured concentrations:
Nominal concentrations: 100 mg/L
Measured concentrations: 100 mg/L (12.6 and 17.9 mg/L, 0 h; 5.89 and 2.07 mg/L, 72 h)
Details on test conditions:
TEST SYSTEM
- Test vessel: 250 mL glass conical flasks each containing 100 mL of solution
- Type: covered with aluminium foil
- Aeration: constantly shaken at 100 rpm
- Initial cells density: 1.26 - 1.66x10E+04 cells/mL
- Control end cells density: 3.64x10E+05 cells/mL
- No. of vessels per concentration: 6
- No. of vessels per control: 3

GROWTH MEDIUM
- Standard medium used: yes, according to OECD guideline

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: reverse osmosis purified deionised water (Elga Optima 15+)

OTHER TEST CONDITIONS
- Adjustment of pH: adjusted to 7.5 ± 0.1 with 0.1 N NaOH or HCl
- Photoperiod: continuous light
- Light intensity and quality: approx. 7000 lux

EFFECT PARAMETERS MEASURED:
- Determination of cell concentrations: samples were taken at 0, 24, 48 and 72 h and the cell densities were determined by using a Coulter Multisizer II Particle Counter

TEST CONCENTRATIONS
- Range finding study
- Test concentrations: 100 mg/L (WAF)
- Results used to determine the conditions for the definitive study: No effect on growth at 100 mg/L loading rate WAF.
Reference substance (positive control):
no
Duration:
72 h
Dose descriptor:
EL50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
(WAF)
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
NOELR
Effect conc.:
>= 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
(WAF)
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EL50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
(WAF)
Basis for effect:
biomass
Details on results:
- Exponential growth in the control: yes
- Any stimulation of growth found in any treatment: an increase of growth was observed in the highest test concentration after 72 h.
- Effect concentrations exceeding solubility of substance in test medium: The nominal effect concentration of 100 mg/L exceeded the water solubility of the test substance.
Reported statistics and error estimates:
Statistical analysis of the area under the growth curve data was carried out for the control and 100 mg/L loading rate WSF test group using a Students t-test.

No effects on the growth rate was observed in the range of water solubility of the test substance with an EL50 of > 100 mg/L based on the growth rate. The measured concentrations of the test item in the test vessels were much lower than the nominal loading rate (Table 3).

Table 1: Cell densities in the definitive study

 

Cell densities [cells/mL]

Nominal loading rate [mg/L]

0 h

24 h

48 h

72 h

Control R1

1.34x104

2.29 x104

7.69 x104

3.79 x105

R2

1.34 x104

2.16 x104

8.80 x104

3.53 x105

R3

1.10 x104

2.22 x104

9.83 x104

3.60 x105

Mean

1.26 x104

2.22 x104

8.78 x104

3.64 x105

100 R1

1.67 x104

2.38 x104

6.14 x104

5.19 x105

R2

1.80 x104

2.42 x104

8.11 x104

5.23 x105

R3

1.37 x104

2.44 x104

6.29 x104

3.50 x105

R4

1.54 x104

2.49 x104

7.26 x104

4.01 x105

R5

1.93 x104

2.41 x104

7.64 x104

6.62 x105

R6

1.61 x104

2.41 x104

6.60 x104

6.65 x105

Mean

1.66 x104

2.42 x104

7.01 x104

5.20 x105

Table 2: Inhibition of growth rate and biomass

Nominal loading rate [mg/L]

Area under curve at 72 h

% inhibition

Growth rate (0-72 h)

% inhibition

control

6.25 x106

-

0.047

 

100

7.51 x106

[20]

0.048

[2]

[increase in growth as compared to the controls]

Table 3: Chemical analysis of test loading rates

Samples

Nominal loading rate [mg/L]

Concentration found [mg/L]

Expressed as a % of the nominal loading rate

0 h

control

< LOQ

-

100 R1-R3

12.6

13

100 R4-R6

17.9

18

72 h

control

< LOQ

-

100 R1-R3

5.89

6

100 R4-R6

2.07

2

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Remarks:
Summary of available data used for the endpoint assessment of the target substance
Adequacy of study:
key study
Justification for type of information:
Please refer to the analogue justification attached to chapter 13.
Reason / purpose:
read-across source
Duration:
72 h
Dose descriptor:
EL50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
WAF
Basis for effect:
growth rate
Remarks on result:
other: source, CAS 131459-39-7, Safepharm, 1999, D. subspicatus
Duration:
72 h
Dose descriptor:
EL50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
WAF
Basis for effect:
biomass
Remarks on result:
other: source, CAS 131459-39-7, Safepharm, 1999, D. subspicatus
Duration:
72 h
Dose descriptor:
NOELR
Effect conc.:
>= 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
WAF
Basis for effect:
growth rate
Remarks on result:
other: source, CAS 131459-39-7, Safepharm, 1999, D. subspicatus
Conclusions:
The substance will not exhibit any effects to aquatic algae up to the limit of water solubility.

Description of key information

Key value for chemical safety assessment

Additional information

Since no studies investigating the toxicity of Fatty acids lanolin, di, tri- and tetraesters with pentaerythritol and rape fatty acid to algae are available, in accordance with Regulation (EC) No 1907/2006 Annex XI, 1.5, a read-across to the structurally related source substance 3,5,5-trimethylhexanoic acid mixed tetraesters with pentaerythritol and valeric acid (CAS 131459-39-7) was conducted.

The source substance is representative to evaluate the toxicity of the target substance to algae. This read-across is justified in detail within the analogue justification in IUCLID Section 13.

The target substance Fatty acids lanolin, di, tri- and tetraesters with pentaerythritol and rape fatty acid is characterized as a UVCB substance with pentaerythritol as alcohol component. Esterification of pentaerythritol gives mainly tri- and tetraesters of long chain fatty acids C16-C20.

The source substance 3,5,5-trimethylhexanoic acid mixed tetraesters with pentaerythritol and valeric acid (CAS 131459-39-7) is characterized by the alcohol component pentaerythritol. Esterification gives mainly tetraesters of 3,5,5-trimethylhexanoic acid and valeric acid.

The study with the source substance 3,5,5-trimethylhexanoic acid mixed tetraesters with pentaerythritol and valeric acid (CAS 131459-39-7) was performed in a static test design according to OECD 201 and EU Method C.3 (GLP).Desmodesmus subspicatuswere exposed to a single nominal loading rate of 100 mg/L (prepared as WAF). No effects on growth rate or biomass were observed after an exposure period of 72 h. Hence an EL50 (72 h) of > 100 mg/L and a NOELR of ≥ 100 mg/L was determined.

Based on the results for the structurally related read-across substance (in accordance with Regulation (EC) No 1907/2006 Annex XI, 1.5) which is characterized by a similar ecotoxicological profile and comparable structure, it can be concluded that no toxicity of the target substance Fatty acids lanolin, di, tri- and tetraesters with pentaerythritol and rape fatty acid to algae is expected up to the limit of the water solubility (< 0.15 mg/L).