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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
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
The study was conduced in accordance with the following guidelines: OECD guidelines for the testing of chemicals n°201, adopted 23 Mar. 2006 "alga, growth inhibition test" EU-guideline C.3:"algal inhibition test" This study was conduced in compliance with the Good Laboratory Practice.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2007
Report Date:
2007

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
yes
Remarks:
No analytical determination of the content of the test item in the solutions during the test was made.
GLP compliance:
yes (incl. certificate)
Remarks:
2007-01-12

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Specification:
Batch n°: T62211
Appearence: pearls of wax
Purity: ES>99%
Solubility: water<0.1g/L
Stability: water96h
Storage: room temperature 20°C+/- 5°C
Hazard information: none as known

Storage
The test item was stored in a closed vessel at room temperature.

Sampling and analysis

Analytical monitoring:
no

Test solutions

Vehicle:
yes
Details on test solutions:
Preparation of the test solution:
As solubility lies below 100mg/L, the water-accomodated fraction was prepared for the test. This was done by weighing of each nominal load, adding the corresponding amount of deionised water and shaking vigorously for 24 hours. The resulting solutions were filtrated through 0.45 um filters.

Test organisms

Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
Strain: CHODAT
Family: Cholrophyceae
Order Chlorococcales

Study design

Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h
Post exposure observation period:
every 24 hours after exposition

Test conditions

Test temperature:
23-25°C
pH:
8.1-10.1
Nominal and measured concentrations:
Nominal concentration for the test item: 0 / 1 / 10 / 100 mg/L
Details on test conditions:
Vessels: round cuvettes d=6mm
Lighting: 4440-8880 Lux
Control: deionised water with nutriment medium and algae
Treatments: test solution with nutriment medium and algae

Study parameters
Date: november 21st-24th 2006
Treatments tested 1/ 10/ 100 mg/L
Number of replicates: six for the control, three for each treament

Alga
Four days before the start of each test, an aliquot of the stock culture containing a few ceels was bhrought into pre-culture medium and incubated for 96 hours. the resulting culture is growing exponentially.
Before usage, the culture was checked for the absence of cell agregates. After the adjustment to a cell concentration of about 10^4/mL through photometric measurment and addition of algal medium, the culture was usable for the test. The adjusted pre-culture was mixed with the same amount of 10-fold nutrient solution. This mixture was the test culture.

Effect parameter measured:
determination of cell concentration with a spectrophotometer


Reference study:
treatments tested: 0.1 / 0.16 / 0.25 / 0.4 / 0.63 / 1.0 / 1.6 mg/L
numer of replicates: six for the control and three for each treament
Reference substance (positive control):
yes
Remarks:
Potassium dichromate (CAS n° 7778-50-9)

Results and discussion

Effect concentrationsopen allclose all
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
ca. 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
ca. 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
cell number
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
ca. 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
cell number
Duration:
72 h
Dose descriptor:
LOEC
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
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
cell number
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Results with reference substance (positive control):
NOEC 72h=0.1mg/L
LOEC 72h=0.16mg/L
72h ECr50=1.1 mg/L
72h EbC50=0.36mg/L
72h EyC50=0.3mg/L
72h-ErC100>1.6mg/L
72h-EbC100>1.6mg/L
72h-EyC100>1.6mg/L

The validity criteria are met.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
Duration Endpoint Effect conc. Nominal/Measured Conc. based on Basis for effect Remarks (e.g. 95% CL)
72 h NOEC ca. 100 mg/L nominal test mat. growth rate
72 h NOEC ca. 100 mg/L nominal test mat. cell number
72 h NOEC ca. 100 mg/L nominal test mat. biomass
72 h LOEC > 100 mg/L nominal test mat. growth rate
72 h LOEC > 100 mg/L nominal test mat. cell number
72 h LOEC > 100 mg/L nominal test mat. biomass
72 h EC50 > 100 mg/L nominal test mat. growth rate
72 h EC50 > 100 mg/L nominal test mat. cell number
72 h EC50 > 100 mg/L nominal test mat. biomass
Executive summary:

The aim of this study was to determine the 72h-EC50 of Montanov 82 against Desmodesmus subspicatus according to OECD 201 resp. EU C.3. The incubation period of 72 hours corresponds to a subchronic test, as during this period, about five cell divisions take place. Selection of the test item was made following the proposal of the guidelines.

As the item is poorly soluble, the water-accomodated fraction was prepared for the test. This was done by weighing of each nominal load, adding the corresponding amount of deionised water and shaking vigorously for 24 hours. The resulting solutions were filtrated through 0.45 um filters.

In the main study, three concentrations of the test item in a geometric series (spaced by factor 10, the highest being 100mg/L) were used. The treatments were used to incubate the unicellular freshwater green alga Desmodesmus subspicatus for a period of 72 hours.

The cell concentration of each replicate was determined by measuring the absorption of cuvettes at 440 nm every 24 hours. with a spectral photometer. With these measured values, the number of cells was calculated (linear correlation between cell concentration and absorption given). Then growth rate, the area under the growth curve (AUC) and the yield could be determined.

The EC50s of potassium dichromate was tested in ac urrent reference test. The values lay within the normal range of the laboratory.

The following results for the test item were determined.

72 h NOEC ca. 100 mg/L

72 h NOEC ca. 100 mg/L

72 h NOEC ca. 100 mg/L

72 h LOEC > 100 mg/L

72 h LOEC > 100 mg/L

72 h LOEC > 100 mg/L

72 h EC50 > 100 mg/L

72 h EC50 > 100 mg/L

72 h EC50 > 100 mg/L