Registration Dossier

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:
10 July 2009 and 06 November 2009
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Modern GLP study conducted in accordance with OECD test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Qualifier:
equivalent or similar to
Guideline:
EU Method C.3 (Algal Inhibition test)
GLP compliance:
yes
Vehicle:
no
Details on test solutions:
An amount of test material (250 mg) was added to the surface of 2.5 litres of culture medium to give the 100 mg/l loading rate. After the addition of the test material, the culture medium was stirred by magnetic stirrer using a stirring rate such that a vortex was formed to give a dimple at the water surface. The stirring was stopped after 23 hours and the mixture allowed to stand for 1 hour. The aqueous phase or WAF was removed by mid-depth siphoning (the first 75-100 ml discarded) to give the 100 mg/l loading rate WAF. Microscopic inspection of the WAF showed no microdispersions or undissolved test material to be present. An aliquot (2 litres) of each of the WAF was inoculated with algal suspension (32 ml) to give the required test concentration of 100 mg/l loading rate WAF. The concentration and stability of the test material in the test preparations were verified by chemical analysis at 0 and 72 hours .

Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Common name: formerly known as Scenedesmus subspicatus
- Strain: CCAP 276/20.
- Source: Culture Collection of Algae and Protozoa (CCAP), Dunstaffnage Marine Laboratory, Oban, Argyll, Scotland
- Age of inoculum (at test initiation):

- Method of cultivation : Prior to the start of the test sufficient master culture was added to approximately 100 ml volumes of culture media contained in conical flasks to give an initial cell density of approximately 103 cells/ml. The flasks were plugged with polyurethane foam stoppers and kept under constant agitation by orbital shaker (100 – 150 rpm) and constant illumination at 24 ± 1°C until the algal cell density was approximately 104 – 105 cells/ml.

ACCLIMATION
- Culturing media and conditions : Culture medium used for both the range-finding and definitive tests was the same as that used to maintain the stock culture. The culture medium was prepared using reverse osmosis purified deionised water (Elga Optima 15+) and the pH adjusted to 7.5 ± 0.1 with 0.1N NaOH or HCl.

Test type:
not specified
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h
Hardness:
no data
Test temperature:
24 ± 1ºC
pH:
pH values at 0h= 7.4
pH values at 72h= 7.7
Dissolved oxygen:
no data
Salinity:
no data
Nominal and measured concentrations:
loading rate of 100 mg/l
Details on test conditions:
TEST SYSTEM
- Test vessel: 250 ml glass conical flask
- Type (delete if not applicable): Sealed with polyurethane foam bungs
- Initial cells density: 4 x 103 cells/ml
- No. of vessels per concentration (replicates): 6 replicate vessels
- No. of vessels per control (replicates): 6 replicate vessels


GROWTH MEDIUM
- Standard medium used: yes (ASTM)

OTHER TEST CONDITIONS
The pH of each control and test flask was determined at initiation of the test and after 72 hours exposure. The pH was measured using a WTW pH 320 pH meter. The temperature within the incubator was recorded daily.
Light intensity and quality: Constant illumination at approximately 7000 lux.


EFFECT PARAMETERS MEASURED :
- Determination of cell concentrations: Cell concentrations were determined for each control and treatment group, using a Coulter® Multisizer Particle Counter.


TEST CONCENTRATIONS
- Range finding study: The range-finding test was conducted by exposing Desmodesmus subspicatus cells to a series of nominal loading rates of 10 and 100 mg/l for a period of 72 hours. Amounts of test material (20 and 200 mg) were each separately added to the surface of 2 litres of culture medium to give the 10 and 100 mg/l loading rates respectively. After the addition of the test material, the culture medium was stirred by magnetic stirrer using a stirring rate such that a vortex was formed to give a dimple at the water surface. The stirring was stopped after 23 hours and the mixtures allowed to stand for 1 hour. The aqueous phase or WAF was removed by mid-depth siphoning (the first 75-100 ml discarded) to give the 10 and 100 mg/l loading rate WAFs. Microscopic inspection of the WAFs showed no micro-dispersions or undissolved test material to be present.The results showed no effect on growth at 10 and 100 mg/l loading rate WAF.

- Test concentrations (nominal value) : 100 mg/l Loading Rate WAF

Reference substance (positive control):
yes
Remarks:
potassium dichromate
Duration:
72 h
Dose descriptor:
EL50
Effect conc.:
> 100 other: mg/l loading rate WAF
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EL20
Effect conc.:
> 100 other: mg/l loading rate WAF
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EL10
Effect conc.:
> 100 other: mg/l loading rate WAF
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
NOELR
Effect conc.:
100 other: mg/l loading rate WAF
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EL50
Effect conc.:
> 100 other: mg/l loading rate WAF
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EL20
Effect conc.:
> 100 other: mg/l loading rate WAF
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EL10
Effect conc.:
> 100 other: mg/l loading rate WAF
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
NOELR
Effect conc.:
100 other: mg/l loading rate WAF
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EL50
Effect conc.:
> 100 other: mg/l loading rate WAF
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: yield
Duration:
72 h
Dose descriptor:
EL20
Effect conc.:
> 100 other: mg/l loading rate WAF
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: yield
Duration:
72 h
Dose descriptor:
EL10
Effect conc.:
> 100 other: mg/l loading rate WAF
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: yield
Duration:
72 h
Dose descriptor:
NOELR
Effect conc.:
100 other: mg/l loading rate WAF
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: yield
Details on results:
The growth rate (r), yield (y) and biomass (b) of Desmodesmus subspicatus (CCAP 276/20) were not affected by the presence of the test material over the 72-Hour exposure period ( see Table 2 & 4 attached).
All test and control cultures were inspected microscopically at 72 hours. There were no abnormalities detected in any of the control or test cultures.
Validity criteria fulfilled:
yes
Conclusions:
The effect of the test material on the growth of Desmodesmus subspicatus has been investigated and gave EL*50 values of greater than 100 mg/l loading rate WAF. Correspondingly the No Observed Effect Loading Rate was 100 mg/l loading rate WAF.
Executive summary:

The effect of the test material on the growth of the green alga Desmodesmus subspicatus was assessed in this study. Following a preliminary range-finding test, Desmodesmus subspicatus was exposed to a Water Accommodated Fraction (WAF) of the test material, at a single nominal loading rate of 100 mg/l (six replicate flasks) for 72 hours, under constant illumination and shaking at a temperature of 24 ± 1°C. Samples of the algal populations were removed daily and cell concentrations determined for each control and treatment group, using a Coulter® Multisizer Particle Counter. Exposure of Desmodesmus subspicatus to the test material gave EL*50 values of greater than 100 mg/l loading rate WAF and correspondingly the No Observed Effect Loading Rate was 100 mg/l loading rate WAF.

Description of key information

A key GLP study reporting 72h EL 50 > 100 mg/l loading rate WAF and NOEL = 100 mg/l loading rate WAF, OECD (201).

Key value for chemical safety assessment

EC50 for freshwater algae:
100 mg/L
EC10 or NOEC for freshwater algae:
100 mg/L

Additional information

In a GLP compliant study, conducted in accordance with the OECD 201 guideline reported that the 72h EC50 for the green alga Desmodesmus subspicatus exposed to the test substance (WAF preparations) at the limit of water solubility, was greater than 100 mg/l in terms of the initial test substance loading rate. Correspondingly the No Observed Effect Loading Rate was 100 mg/l loading rate WAF.