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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
Study period:
07/08/2015-27/11/2015
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2016
Report date:
2016

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Chemical structure
Reference substance name:
1,3-dioxane, 2-(3,3-dimethyl-1-cyclohexen-1-yl)-2,5,5-trimethyl
Cas Number:
1853175-99-1
Molecular formula:
C15H26O2
IUPAC Name:
1,3-dioxane, 2-(3,3-dimethyl-1-cyclohexen-1-yl)-2,5,5-trimethyl
Specific details on test material used for the study:
Test item : Maderal (Reference ZA1076)
Batch N°100026324
Received the 08/07/2015 from the sponsor
Colourless translucent liquid
Certified purity: 97.5%
Stored at room temperature, protected from directed sunlight

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
The algal biomass in each flask was determined daily over the test period using small volumes removed from the test solution by pipette. These volumes were not replaced.
The numeration was done using an electronic cell counter. The results were expressed as cells per liter of solution.

Daily, small volumes were removed from the test solution by pipette. These volumes were not replaced

Test solutions

Vehicle:
yes
Remarks:
acetone

Test organisms

Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
Strain N°72 of the Museum National d'Histoire Naturelle (Paris)
The inoculum culture was prepared 2-4d before the start of the test, in acclimating conditions and in order to ensure that the algae were in the exponential growth phase when used to inoculate the test solutions

Study design

Test type:
semi-static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h
Post exposure observation period:
The cells appeared healthy in the controls and the test item treatments

Test conditions

Test temperature:
Range of 21-24°C, kept constant to within +/- 2°C
pH:
Measured at the beginning/end of the test. It did not increase by 1.5 unit the test
pHinitial/final in water control: 8.2/9.2
pH initial/final in solvent control: 8.2/9.2
Nominal and measured concentrations:
Nominal concentrations: 2.0 ; 3.0 ; 4.4 ; 6.7 ; 10 mg a.i./L
Measured concentrations: 0.6 ; 1.0 ; 1.5 ; 2.0 ; 3.5 mg a.i./L
Details on test conditions:
Illumination : uniform/fluorescent of 60-120 µE.m-2.s-1
Light intensity did not deviate by more than 15% from the average light intensity
Reference substance (positive control):
yes
Remarks:
Potassium Dichromate

Results and discussion

Effect concentrationsopen allclose all
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 3.5 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 3.5 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
act. ingr.
Basis for effect:
other: yield
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
ca. 3.5 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
ca. 3.5 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
act. ingr.
Basis for effect:
other: yield
Results with reference substance (positive control):
Specific growth rate : EC50-72h between 0.6 and 1.0 mg/L. Calculation gave 0.87 mg/L as the measured value.
Yield: EC50-72h between 0.2 and 0.75 mg/L Calculation gave 0.40 mg/L as the measured value.
The resultas fulfilled the validity criteria base on Phytosafe historical data
Reported statistics and error estimates:
Specific growth rate : The Standard deviation between the three replicates units did not exceed 8% of the mean value at each sampling time and was less than 2% for the average specific growth rate per day over the entire test period. F-variance analysis at 5% confidence level was used to to judge upon the difference for mean specific growth rate (section by section and total values) for each test item treatment compared to the water control : no significant difference was observed for the solvent control control and the test item.

Any other information on results incl. tables

No regression curve was calculated because there was no significant effect over the test range, and the EC50 -72h was reported as > 3.5 mg a.i./L (the highest test substance concentration)

Specific Growth rate of the water/solvent control (total period, mean of the three replicates): 1.63 +/-0.01

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Executive summary:

The toxicity to aquatic algae and cyanobacteria test was performed according to OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test).

Based on specific growth rate:

NOEC = 3.5 mg a.i/L

EC50-72h > 3.5 mg/L

Based on yield:

NOEC: 3.5 mg a.i./L

EC50-72h > 3.5 mg a.i./L