Oxaceprol

Toxicity to aquatic algae and cyanobacteria

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:

2017-07-03 to 2017-08-04

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)

Version / remarks:

2011-07-28

Qualifier:

according to guideline

Guideline:

other: Commission Regulation (EC) No 761/2009, Annex, Part C, C.3.: "Freshwater Algae and Cyanobacteria, Growth Inhibition Test", Official Journal of the European Union (EN)

Version / remarks:

2009-08-24

Qualifier:

according to guideline

Guideline:

other: SANCO/3029/99 rev.4 11/07/00: Residues: Guidance for generating and reporting methods of analysis in support of pre-registration data requirements for Annex II (part A; Section 4) and Annex III (part A; Section 5) of directive 91/414

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: Nippon Rika Co., Ltd. / lot 6716-16E
- Expiration date of the lot/batch: 2018-10-23
- Purity test date: 2016-11-17

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: At 20°C +/- 5°C, in the dark
- Solubility and stability of the test substance in the solvent/vehicle: highly soluble

Analytical monitoring:

yes

Details on sampling:

The samples were taken from the biological phase of the study. Duplicate samples from the freshly prepared test media (containing algae) of all test concentrations and from the control were taken at the start of the test.
For the determination of the stability of the test item under the test conditions and of the maintenance of the test item concentrations during the test period, duplicate samples from the test media of all test concentrations and the control (containing algae) were taken at the end of the test (after the 72 hours test period) by pouring together the contents of the test beakers of each treatment.
The samples were diluted by a factor of two with acetonitrile.
One additional sample of the control and of the dilution solvent was taken at test start and test end without any sample treatment.

All samples were stored in a freezer (≤ - 20 °C), protected from light until analysis was performed. Afterwards the samples were again stored deep frozen (≤ -20 °C) and were kept stored up to the date of the final report.

The concentrations of the test item Oxaceprol were analysed in the duplicate test media samples from all test concentrations, and in the duplicate control samples, from both sampling times (0 and 72 hours).

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Weighed amounts were dissolved; stock solution was diluted
- Controls: Reconstuted water, potassium dichromate (historical)
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): reconstuted water (OECD medium)
- Concentration of vehicle in test medium (stock solution and final test solution(s) or suspension(s) including control(s)): stock solution: 100 mg/L; test concentrations were 100, 32, 10, 3.2 and 1.0 mg/L
- Evidence of undissolved material (e.g. precipitate, surface film, etc.): all test material dissolved

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: Pseudokirchneriella subcapitata
- Strain: Strain No. 61.81 SAG
- Source (laboratory, culture collection): „Sammlung von Algenkulturen, Albrecht-von-Haller-Institut für Pflanzenwissenschaften, Universität Göttingen", 37073 Göttingen, Germany
acclim - Method of cultivation: The algae were cultivated in the laboratories of ibacon under standardised conditions according to the test guidelines

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Hardness:

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

Test temperature:

21.9 to 22.9 °C

pH:

8.0 at test start, 9.1 to 9.2 at test end

Nominal and measured concentrations:

fresh aged mean measured concentrations [mg/L]
mg/L % of nominal RSD % of nominal RSD
1 84 6 76 3 0.798
3.2 76 5 76 4 2.42
10 81 1 79 4 8.00
32 78 6 72 6 24.1
100 91 5 81 0 85.8
Number of analysed samples: 4 each
RSD: relative standard deviation

Details on test conditions:

TEST SYSTEM
- Test vessel: Erlenmeyer flasks of 50 mL volume with 50 mL of test medium
- Type (delete if not applicable): closed
- Material, size, headspace, fill volume: glass
- Initial cells density: approx. 5000/mL
- Control end cells density: yes
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): positive control by historical data
- No. of vessels per vehicle control (replicates): 1 per test concentration

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
Analytical grade salts were added at the following nominal concentrations in deionised water:
Macronutrients:
NaHCO3 50.0 mg/L
CaCl2 x 2 H2O 18.0 mg/L
NH4Cl 15.0 mg/L
MgSO4 x 7 H2O 15.0 mg/L
MgCl2 x 6 H2O 12.0 mg/L
KH2PO4 1.6 mg/L
Trace elements:
Na2EDTA x 2 H2O 100.0 µg/L
FeCl3 x 6 H2O 64.0 µg/L
MnCl2 x 4 H2O 415.0 µg/L
H3BO3 185.0 µg/L
Na2MoO4 x 2 H2O 7.0 µg/L
ZnCl2 3.0 µg/L
CoCl2 x 6 H2O 1.5 µg/L
CuCl2 x 2 H2O 0.01 µg/L

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: no
- Photoperiod: continuous illumination
- Light intensity and quality: Mean light intensity: 7058 lux (range: 6320 to 7470 lux)


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: spectrophotometer

TEST CONCENTRATIONS
- Range finding study: yes
- Test concentrations: 100, 32, 10, 3.2, 1.0 mg/L corresponding to following mean measured concentrations of the test item:
85.8, 24.1, 8.00, 2.42 and 0.798 mg/L

Reference substance (positive control):

yes

Remarks:

Most recent test with the test item potassium dichromate perforemd in November / December 2016

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

85.8 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

> 85.8 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 85.8 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC20

Effect conc.:

> 85.8 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

> 85.8 mg/L

Nominal / measured:

meas. (arithm. mean)

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
- Unusual cell shape: no
- Colour differences: no
- Flocculation: no

Results with reference substance (positive control):

- Results with reference substance valid? yes
- EC50: 1.12 mg/L (growth rate)

Reported statistics and error estimates:

Based on the calculated cell densities, the 72 hours ErC50 and the 72 hours EyC50 could not be calculated by Probit analysis due to the lack of effects and were therefore determined directly from the raw data.
For the determination of the 72 hours LOEC and the 72 hours NOEC, the calculated growth rates and yields at each test concentration were tested for significant differences compared to the control values by Dunnett´s t-test.
The software used to perform the statistical analysis was ToxRat Professional, Version 3.2.1, ToxRat Solutions GmbH.

Validity criteria fulfilled:

yes

Conclusions:

Oxaceprol did not exhibit aquatic toxicity to Pseudokirchneriella subcapitata in a study according to OECD 201 under the conditions of the test.

Executive summary:

The influence of Oxaceprol on the growth of the freshwater green algae Pseudokirchneriella subcapitata was assessed in a static concentration-response test according to OECD 201. The 72-hour E_yC₅₀ was calculated to be > 85.8 mg test item/L and the 72-hour E_rC₅₀ value was calculated to be > 85.8 mg test item/L. The 72-hour NOE_yC was determined to be 85.8 mg test item/L and the associated 72-hour LOE_yC was > 85.8 mg test item/L. The 72-hour NOE_rC was determined to be 85.8 mg test item/L and the associated 72-hour LOE_rC was > 85.8 mg test item/L.

The quantification of the test item Oxaceprol in the test samples was performed using liquid chromatography with MS/MS detection.

At the start of the test 82% of the nominal test concentrations were found (average of all test concentrations). After 72 hours test duration, 77% of the nominal value was determined (average of all test concentrations). During the test the algae were exposed to a mean of 79% of nominal. All reported results refer to mean measured values since the initial measured concentrations of the test item were not within± 20% of the nominal concentrations.

Description of key information

Oxaceprol did not exhibit aquatic toxicity to Pseudokirchneriella subcapitata in a study according to OECD 201 under the conditions of the test.

Key value for chemical safety assessment

EC50 for freshwater algae:

85.8 mg/L