Ethanol, 2-[(3-nitropyrazolo[1,5-a]pyridin-2-yl)oxy]-

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:

From August 08, 2014, to February 03, 2015

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Well described study performed according to OECD guideline and GLP

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2015

Report date:

2015

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Deviations:

no

GLP compliance:

yes

Remarks:

Certificate available in the attached report.

Test material

Test material information

Constituent 1

Reference substance name:

2-({3-nitropyrazolo[1,5-a]pyridin-2-yl}oxy)ethan-1-ol

EC Number:

938-829-3

Cas Number:

936103-10-5

Molecular formula:

C9H9N3O4

IUPAC Name:

2-({3-nitropyrazolo[1,5-a]pyridin-2-yl}oxy)ethan-1-ol

Constituent 2

Reference substance name:

2-[(3-Nitropyrazolo[1,5-a]pyridin-2-yl)oxy] ethanol

IUPAC Name:

2-[(3-Nitropyrazolo[1,5-a]pyridin-2-yl)oxy] ethanol

Test material form:

solid: particulate/powder

Remarks:

migrated information: powder

Test solutions

Details on test solutions:

5.0, 1.6, 0.5, 0.2, 0.05 and 0.02 mg test item/L, and a control; corresponding to the following geometric mean measured concentrations: 4.80, 1.57, 0.505, 0.182, 0.046 and 0.017 mg test item/L, and a control.

Test organisms

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

The algae were supplied by the "Sammlung von Algenkulturen, Albrecht-von-Haller-Institut für Pflanzenwissenschaften, Universität Göttingen", 37073 Göttingen, Germany.

Study design

Test type:

static

Water media type:

saltwater

Total exposure duration:

72 h

Test conditions

Hardness:

Calculated water hardness of the test water: 0.24 mmol/L (= 24 mg/L) as CaCO3.

Test temperature:

22-23°C

pH:

pH values at test start 7.8 to 8.1, at the end of the test 7.7 to 8.6;

Salinity:

Reconstituted Water (OECD Medium):
Analytical grade salts were added at the following nominal concentrations in deionised water (conductivity <5 μScm-1):
Macro-nutrients:
NaHCO3 50.0 mg/L
CaCl2 × 2 H2O 18.0 mg/L
NH4Cl 15.0 mg/L
MgSO4 × 7 H2O 15.0 mg/L
MgCl2 × 6 H2O 12.0 mg/L
KH2PO4 1.6 mg/L

Details on test conditions:

Introduction of Algae:
The test was started (0 hours) by inoculation of a biomass of 5000 algal cells per mL test medium. These cells were taken from an exponentially growing pre-culture, which was set up 3 days prior to the test start under the same conditions as in the test.
Replicates:
The test was performed with three replicates per test concentration and six replicates in the control. Volumes of 50 mL of algal suspension per replicate were continuously stirred with magnetic stirrers in 50 mL Erlenmeyer flasks. The flasks were covered with glass dishes and incubated in a water bath. The flasks were placed in a random order and were repositioned each day to minimize differences in test conditions.
Blanks:
Additionally, one replicate of each test concentration and of the control was prepared without algae to provide a "blank" for the spectrophotometrical measurements. The additional replicates were incubated under the same conditions as described above. The blank values were subtracted from the absorption measured in the samples containing algae in order to eliminate absorption caused by the test item (see also "Determination of the Cell Density").
Exposure Time:
72 hours
Determination of the Cell Density:
The cell densities in the samples were determined by spectrophotometrical measurement. Therefore defined volumes of the algal suspensions from all replicates and from the blanks were sampled after 24, 48 and 72 hours of exposure, and were not replaced.
The algal cell densities were calculated by subtracting the absorption of the blanks, from each of the measured absorption of the test media (with algae).
The cell densities in a number of samples from the pre-culture were counted by microscope before test start. Out of this pre-culture eight defined dilutions were prepared and measured spectrophotometrically. Based on the counted cell densities and the absorption of the pre-culture sample and the dilutions, a linear regression was performed for the calculation of the cell densities in all other samples measured spectrophotometrically during the test.

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

ca. 0.45 mg/L

Basis for effect:

growth rate

Remarks on result:

other: 0.323-0.624

Effect concentrations 2

Duration:

72 h

Dose descriptor:

EC20

Effect conc.:

ca. 0.131 mg/L

Basis for effect:

growth rate

Remarks on result:

other: 0.064-0.197

Effect concentrations 3

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

ca. 0.063 mg/L

Basis for effect:

growth rate

Remarks on result:

other: 0.023-0.110

Effect concentrations 4

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

ca. 0.046 mg/L

Basis for effect:

growth rate

Effect concentrations 5

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

ca. 0.182 mg/L

Basis for effect:

growth rate

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The influence of R0056895A on the growth of the freshwater green algae Pseudokirchneriella subcapitata was assessed in a static dose-response test. The 72-hour EyC50 was calculated to be 0.450 mg test item/L and the 72-hour ErC50 value was calculated to be 2.15 mg test item/L. The 72-hour NOEyC was determined to be 0.046 mg test item/L and the associated 72-hour LOEyC was 0.182 mg test item/L. The 72-hour NOErC was determined to be 0.182 mg test item/L and the associated 72-hour LOErC was 0.505 mg test item/L.