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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:
31 December 1991 and 3 January 1992
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
- Concentrations: 100 mg/L
- Sampling method: duplicate water samples were taken
- Sample storage conditions before analysis: samples stored at -20°C until analysis by Sponsor.
Vehicle:
no
Details on test solutions:
Direct dispersion in algal media with the aid of ultrasonic disruption
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Common name: Scenedesmus subspicatus
- Strain: CCAP 276/20
- Source (laboratory, culture collection): Culture Centre of Algae & Protozoa c/o Freshwater Biological Association, Cumbria, U.K.
- Age of inoculum (at test initiation):
- Method of cultivation:Sterile nutrient medium was inoculated from a master culture and incubated under continuous illumination (approx. 7000 lux) and stirring (orbital shaker) at 24 degree C to give an algal suspension in log phase growth characterised by an absorbance of 0.210 (at 665 nm).
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h
Post exposure observation period:
Not applicable
Hardness:
Not applicable
Test temperature:
24 ± 1 °C
pH:
7.2 - 8.4
Dissolved oxygen:
Not applicable
Salinity:
Not applicable
Nominal and measured concentrations:
Nominal: 100 mg/L; Mean measured 114 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel:
- Type : 250 ml conical flask
- Material, size, headspace, fill volume: glass vessels containing 100 ml test solution
- Aeration: none. gaseous exchange and suspension of algal cells maintained by orbital shaker.
- Initial cells density: 0.85 x 10^4 cells/ml
- Control cells density after 72 hours exposure: 1.5 x 10^6 cells/ml

- No. of vessels per concentration (replicates): six
- No. of vessels per control (replicates):three


GROWTH MEDIUM
- Standard medium used: yes


OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: not specified
- Photoperiod:continuous
- Light intensity and quality:7000 lux


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : 0, 24, 48 and 72 hours
- Determination of cell concentrations: absorbance measured at 665 nm. Cell densities of the control cultures at initiation and at termination were determined by direct counting with the aid of a haemacytomter.
Reference substance (positive control):
no
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Details on results:
- Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test): no abnormalities detected
Results with reference substance (positive control):
Not applicable
Reported statistics and error estimates:
Statistics used were detailed in the guudeline.

The area under the growth curve after 72 hours was as follows:

Control - 7.116

100 mg/L - 7.448

The growth rate, 48 - 72 hours was as follows:

Control - 0.043

100 mg/L - 0.042

Validity criteria fulfilled:
yes
Conclusions:
The freshwater algae Scenedesmus subspicatus was exposed to a nominal exposure concentration of 100 mg/L dipentaerythritol for 72 hours under static conditions. The mean measured concentration of the 100 mg/L test treatment was 114 mg/L which indicated that the test medium had been adequately prepared. As the measured concentration was within +/- 20% of the nominal concentration the results of the study are based on the nominal exposure concentration. No effects were seen on either growth rate or biomass, therefore the 72 hour EbC50 and 72 hour ErC50 were both >100 mg/L, the corresponding no-observed effect concentrations (NOEC) were both observed to be 100 mg/L.
Executive summary:

In a 72 hour acute toxicity study, cultures of the freshwater algae Scenedesmus subspicatus  were exposed to dipentaerythritol at nominal concentrations of 0 (control) and 100 mg/L under static conditions in accordance with the OECD guideline 201 (Version 23 March 2006). The mean measured concentration of the 100 mg/L test treatment was 114 mg/L which indicated that the test medium had been adequately prepared. As the measured concentration was within +/- 20% of the nominal concentration the results of the study are based on the nominal exposure concentration. No effects were seen on either growth rate or biomass, therefore the 72 hour EbC50 and 72 hour ErC50 were both >100 mg/L, the corresponding no-observed effect concentrations (NOEC) were both observed to be 100 mg/L.


 


No abnormalities were noted.


 


This toxicity study is classified as acceptable and satisfies the guideline requirements for toxicity to aquatic algae and cyanobacteria toxicity study. 


 


Results Synopsis 


Test Organism: Scenedesmus subspicatus


Test Type: Static                     


72 hr EC50:     > 100 mg/L and > 100mg/L (biomass and growth rate, respectively)    


72 hr NOEC:  > 100 mg/L and > 100 mg/L  (biomass and growth rate, respectively)


Endpoint(s) Effected:  biomass, growth rate

Description of key information

The freshwater algae Scenedesmus subspicatus was exposed to a nominal exposure concentration of 100 mg/L dipentaerythritol for 72 hours under static conditions. The mean measured concentration of the 100 mg/L test treatment was 114 mg/L which indicated that the test medium had been adequately prepared. As the measured concentration was within +/- 20% of the nominal concentration the results of the study are based on the nominal exposure concentration. No effects were seen on either growth rate or biomass, therefore the 72 hour EbC50 and 72 hour ErC50 were both >100 mg/L, the corresponding no-observed effect concentrations (NOEC) were both observed to be 100 mg/L.

Key value for chemical safety assessment

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

Additional information

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