Registration Dossier

Ecotoxicological information

Short-term toxicity to aquatic invertebrates

Administrative data

Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
13 May 2013 to 18 March 2014
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Conducted according to current test guidelines and GLP-compliant

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2014
Report date:
2014

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
no
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Chemical structure
Reference substance name:
Acetic acid 2-oxo-2H-pyridin-1-yl ester
EC Number:
689-986-7
Cas Number:
1742-79-6
Molecular formula:
C7H7NO3
IUPAC Name:
Acetic acid 2-oxo-2H-pyridin-1-yl ester
Constituent 2
Reference substance name:
1742-78-6
IUPAC Name:
1742-78-6
Test material form:
solid: particulate/powder
Remarks:
migrated information: powder
Details on test material:
Name: Oxypyrionacetate
CAS number: 1742-78-6
Batch number: 14058400
Purity: 99.96%
Expiry date: 30 November 2013
Storage details: Refrigerated (2 to 8ºC)
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
Not applicable

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
- Concentrations: 0.1, 1.0, 10 and 100 mg/L
At the start of the test (0 hours), duplicate 20 mL samples of freshly prepared test media were taken from the control and the test concentration media preparation flasks for chemical analysis.
At 48 hours, duplicate 20 mL samples were taken for chemical analysis from the pooled expired test media from all test concentrations and control.

Test solutions

Details on test solutions:
The dilution water used in the study was ASTM medium. The range-finding / limit test was conducted at nominal test substance concentrations of 0.1, 1.0, 10 and 100 mg/L. A control group containing ASTM medium only was also included.

Test organisms

Test organisms (species):
Daphnia magna
Details on test organisms:
Juvenile Daphnia magna (Straus), less than 24 hours old, were taken from healthy parental laboratory cultures, held and maintained at the test facility.

Study design

Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
48 h
Post exposure observation period:
Not applicable

Test conditions

Hardness:
150 mg/L CaCO3
Test temperature:
18.6 – 18.9
pH:
6.75 to 8.25
Dissolved oxygen:
97-102%
Salinity:
Not applicable
Nominal and measured concentrations:
Nominal concentrations: 0.1, 1.0, 10 and 100 mg/L
Geometric mean measured concentrations: 0.0121, 0.703, 6.86 and 70.1 mg/L
Details on test conditions:
The test was conducted using static test conditions with no renewal of test media.
The test vessels (nominal volume 150 mL) were glass crystallising dishes with clear lids each containing 100 mL of the appropriate media. Two replicate test vessels were prepared for the 0.1, 1.0 and 10 mg/L concentrations and four replicate test vessels were prepared for the control and 100 mg/L test concentration.
Five juvenile Daphnia magna, less than 24 hours old, were added to each replicate vessel, using a wide bore glass pipette to avoid damaging the animals during transfer. The Daphnia magna were not fed during the test.
After 24 and 48 hours, the Daphnia magna in each test vessel were observed for evidence of immobility. The observations differentiated between mobile and immobile daphnids. An individual was considered immobile if, when the contents of the test vessel were briefly agitated, it did not swim during a 15-second period of observation. In addition, Daphnia magna submerged in the body of the test media and those that were held at the surface of the test media were also recorded.
The test was conducted with a 16-hour light: 8-hour dark photoperiod.
The pH, dissolved oxygen concentration (% air saturation value (ASV) and mg/L) and temperature were determined in freshly prepared test media at the start of the test. Continuous temperatures were measured using a digital (min/max) thermometer in an additional vessel maintained in the study arena.
At the end of the exposure period the test water quality measurements were conducted using pooled replicate samples of old test media at each of the test media concentrations.
Total hardness and alkalinity of the freshly prepared ASTM medium was determined at the start of the test.
Reference substance (positive control):
not required

Results and discussion

Effect concentrationsopen allclose all
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
> 70.1 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
act. ingr.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
> 70.1 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
act. ingr.
Basis for effect:
mobility
Details on results:
After 48 hours, the concentration at which no significant (≤10%) immobility occurred was 70.1 mg/L. The NOEC was therefore 70.1 mg/L, relating to the degradation product Oxypyrion.
The 48-hour EC50 value was determined to be greater than 70.1 mg/L, relating to the degradation product Oxypyrion.
Results with reference substance (positive control):
Not applicable
Reported statistics and error estimates:
Not applicable

Any other information on results incl. tables

Geometric Mean Measured Concentration (mg/L)of
Degradation Product Oxypyrion

Number of
Daphnia magna
exposed

%
Immobility at 24 hours

%
Immobility at 48 hours

Control

20

0

0

0.0311

10

0

0

0.703

10

0

0

6.87

10

0

0

70.1

20

0

10

 

 

Geometric Mean Measured Concentration (mg/L)

of Degradation Product Oxypyrion

24 hours

48 hours

EC50

>70.1

>70.1

NOEC

70.1

70.1

 

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The 48-hour acute toxicity of Oxypyrionacetate to the freshwater planktonic crustacean, Daphnia magna, was determined in accordance with the requirements of OECD Chemicals Testing Guideline No. 202 Daphnia sp. Acute Immobilisation Test (adopted April 13 2004).
The validity criteria for control immobility (≤10%) and dissolved oxygen (>60% ASV) were both satisfied. The test is therefore considered valid.
As the measured concentrations were outside the range of 80-120% of nominal exposure concentrations of Oxypyrion which is required to report the test concentrations in terms of nominal concentrations, the test concentrations therefore, were reported as geometric mean measured concentrations.
After 48 hours, the concentration at which no significant (≤10%) immobility occurred was 70.1 mg/L. The NOEC was therefore 70.1 mg/L, relating to the degradation product Oxypyrion.
The 48-hour EC50 value was determined to be greater than 70.1 mg/L, relating to the degradation product Oxypyrion.
Executive summary:

The objective of the study was to determine the 48-hour acute toxicity of Oxypyrionacetate to the freshwater planktonic crustacean, Daphnia magna using semi‑static test conditions. The study was conducted in accordance with the requirements of OECD Chemicals Testing Guideline No. 202 Daphnia sp. Acute Immobilisation Test (adopted April 13 2004).

A static, range-finding test was conducted at concentrations 0.1, 1.0, 10 and 100 mg/L; however, due to variable toxicity results, the range finding test was repeated as a range-finding / limit test. The initial range-finding data has been reported at the client’s request.

The static, range-finding / limit test was conducted at concentrations 0.1, 1.0, 10 and 100 mg/L. A control group was also included.

At the start of the test, five juvenile Daphnia magna were added to each test vessel. TheDaphnia magnain each test vessel were observed at 24 and 48 hours. The Daphnia magna were not fed during the test.

The expiry date of the test substance was 30 November 2013; however, the test substance was re-analysed to confirm that the composition had not altered (purity of 99.8%). The test substance was considered acceptable for use on this study.

Initial method development, conducted under Smithers Viscient study 3200294, indicated that at a room temperature of ~20°C, the test substance readily degraded over a period of approximately 3.5 hours. Therefore, due to the test substance rapid degradation it was decided to analyse the degradation product (Oxypyrion) as opposed to the parent compound (Oxypyrionacetate).

Samples of test media were taken for chemical analysis at 0 hour (new test media) and at 48 hours (old test media). 

Analysis of the 0 hour samples showed concentrations of Oxypyrion to range between 60% and 74% of nominal concentrations.

Analysis of the old media at 48 hours showed concentrations of Oxypyrion to range between 63% and 71% of nominal concentrations, with the exception of the 0.1 mg/L concentration. The recovery for 0.1 mg/L was significantly reduced (3% of nominal) however, as the NOEC value was 100 mg/L, this anomaly was considered not to impact the test.

As the measured concentrations were outside the range of 80-120% of nominal exposure concentrations of Oxypyrion, which is required to report the test concentrations in terms of nominal concentrations, the test concentrations were therefore reported as geometric mean measured concentrations.

The 24 and 48-hour EC50 values and the corresponding NOEC values were derived empirically from the data and are presented in the table below.


 

Geometric Mean Measured Concentration (mg/L)
of Degradation Product Oxypyrion

 

24 hours

48 hours

EC50

>70.1

>70.1

NOEC

70.1

70.1

 

As no significant toxicity was observed during the test it can be empirically derived that the 24-hour toxicity results were greater that the geometric mean measured concentration for the test.

After 48 hours, the concentration at which no significant (≤10%) immobility occurred was 70.1 mg/L. The NOEC was therefore 70.1 mg/L, relating to the degradation product Oxypyrion.

The 48-hour EC50 value was determined to be greater than 70.1 mg/L, relating to the degradation product Oxypyrion.

The validity criteria for control immobility (≤10%) and dissolved oxygen (>60% ASV) were both satisfied. The test is therefore considered valid.