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:
2003
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: The study was conducted according to OECD TG 202 and in accordance with Good Laboratory Practice (GLP).
Cross-referenceopen allclose all
Reason / purpose:
reference to same study
Reason / purpose:
reference to other study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2003
Report Date:
2003

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
Deviations:
no
Qualifier:
according to
Guideline:
EPA OTS 797.1300 (Aquatic Invertebrate Acute Toxicity Test, Freshwater Daphnids)
Deviations:
no
Principles of method if other than guideline:
None
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): n- propyl propionate
- Molecular formula: C6H12O2
- Physical state: liquid
- Analytical purity: 99.96%
- Lot/batch No.: QC1355V1C1
- Stability under test conditions: Stable under test conditions
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: Nominal test concentrations: 0 (water control), 6.25, 12.5, 25.0, 50.0, 100, and 200 mg n- propyl propionate/l, Measured test concentrations: less than the lowest level quantified of 0.628 mg/l for the water control and 4.24, 8.75, 17.5, 35.9, 63.7, and 149 mg/l for the treatment solutions.
- Sampling method: Aliquots (2 ml) were collected from the test solutions (bulk dose solutions and ALDW control on day 0, replicate spent test solutions and renewed bulk dose solutions and ALDW control on day 1, and replicate spent test solutions on day 2).

Test solutions

Vehicle:
yes
Details on test solutions:
For the definitive test, bulk solutions were prepared in ALDW at nominal (target) exposure concentrations of 6.25, 12.5, 25.0, 50.0, 100, and 200 mg n- propyl propionate/L, at test initiation and renewed at approximately 24 hours. These bulk dose solutions, in addition to control test solution (ALDW with no test material added and referred to as water control) were apportioned (~200 mL) between two replicate test vessels per dose level.

Test organisms

Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Daphnia magna
- Strain: straus
- Source: Aquatic Biosystems, Fort Collins, Colorado
- Age at study initiation (mean and range, SD): < 24 hrs
- Feeding during test: yes
- Food type: mixed diet of Selenastrum capricornutum (algae) and YCT (yeast-ceraphyll trout) trout chow

Study design

Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Post exposure observation period:
Not applicable

Test conditions

Hardness:
132–180 mg/l (as CaCO3).
Test temperature:
19.5–20.7 °C
pH:
7.1–7.6 (7.3 ± 0.2)
Dissolved oxygen:
7.2–8.8 (8.2 ± 0.5) mg/l
Salinity:
Not available
Nominal and measured concentrations:
Nominal concentrations: 0 (water control), 6.25, 12.5, 25.0, 50.0, 100, and 200 mg n-Propyl Propionate/l
Measured concentrations: 4.24, 8.75, 17.5, 35.9, 63.7, and 149 mg n-Propyl Propionate/l.
Details on test conditions:
TEST SYSTEM
- Test vessel: 250-ml glass beakers filled with 200 ml of control or test solution.
- Type (delete if not applicable): open / closed : loosely covered
- Material, size, headspace, fill volume: 250-ml
- Renewal rate of test solution (frequency/flow rate): 24 hrs
- No. of organisms per vessel: 10 daphnids
- No. of vessels per concentration (replicates): 2 per concentration
- No. of vessels per control (replicates): 2


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: The water was obtained from the upper Saginaw Bay of Lake Huron off Whitestone Point
- Total organic carbon: <2000 ug/l
- Chlorine: <10 ppb
- Alkalinity: 36 mg/L CaCO3
- Ca/mg ratio: 7:1
- Conductivity: 365–391 mmhos/cm.

OTHER TEST CONDITIONS
- Adjustment of pH: pH adjusted with gaseous CO2
- Photoperiod: 16-hour light/8-hour dark
- Light intensity: 1824–2080 lux (1944 ± 85 lux).

TEST CONCENTRATIONS
- Range finding study : Yes
- Results used to determine the conditions for the definitive study: yes
Reference substance (positive control):
no

Results and discussion

Effect concentrationsopen allclose all
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
59.6 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 49.8–73.5 mg/L
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
37.8 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 31.6–44.6 mg/L
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
17.5 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
Immobility was observed in 100% (20/20), 50% (10/20), 15% (3/20), and 5% (1/20) of the Daphnia at the 149, 63.7, 35.9, and 4.24 mg/L dose levels following 24 hours ofexposure. Following 48-hours of exposure, immobility was observed in 100% (20/20), 90% (18/20), 50% (10/20), 5% (1/20), 5% (1/20), and 5% (1/20) of the Daphnia at the 149, 63.7, 35.9, 8.75, 4.24 mg/L dose levels and the water control, respectively. No immobility was observed in the 17. mg/L dose level during the conduct of the study.
The one Daphnia observed immobile in the 4.24 mg/L was believed to be incidental since this effect was first observed following 24-hours of exposure while no Daphnia in the next two highest dose levels (8.75 and 17.5 mg/L) exhibited any adverse effects at this same time point. In addition, the one Daphnia that was observed immobile in both the water control and the 8.75 mg/L dose level at test termination (48-hours) were also believed to be incidental. Both of the immobile Daphnia were observed trapped in the screen of the test vessel screen inserts. Therefore, it appears that this immobilization was most likely due to a physical obstruction from the screen insert within the test vessels, which may have occurred during test solution renewal, rather than exposure to the test chemical. This assumption is also supported by the fact that no Daphnia at the higher 17.5 mg/L dose level were observed immobile at any time during the conduct of this study. Therefore, the immobile Daphnia observed in the water control and in the 4.24 and 8.75 mg/L dose levels were not included in the statistical evaluation of the data.
Results with reference substance (positive control):
Not applicable
Reported statistics and error estimates:
An appropriate U.S. EPA computer program was used to calculate the EC50 values and corresponding 95% confidence intervals, when possible.
Based on the biological response observed following 24- and 48-hours of exposure, the U.S. EPA Probit Program, Version 1.5, was the method used to calculate the 24- and 48- hour EC50 values and corresponding 95% confidence intervals.
The 48-hour NOEC was determined based on biological interpretation of the data and the highest exposure level exhibiting no Daphnia immobility.

Any other information on results incl. tables

Preliminary test:

A 48-hour static probe study was conducted with one replicate of ten Daphnia per dose level exposed to nominal test concentrations of 0 (water control), 2.5, 5.00, 25.0, 50.0, 250, and 500 mg npropyl propionate/L. Immobility was observed in 100% (10/10) of the Daphnia at both the 250 and 500 mg/L dose levels following 48-hours of exposure. Analytical chemistry verification of the test solutions during the probe indicated that the test material was not stable under these test conditions. As a result of this, the probe study was repeated and conducted under static-renewal conditions (renewal of test solutions at ~24 hours).

The 48-hour static-renewal (renewal of test solutions at ~24 hours) probe study was conducted between 08 July and 10 July 2003 with one replicate of ten Daphnia per dose level exposed to nominal test concentrations of 0 (water control), 15.6, 31.3, 62.5, 125, and 250 mg n-propyl propionate/L. Immobility was observed in 100% (10/10) of the Daphnia at the 250, 125, and 62.5 mg/L dose levels and 60% (6/10) of the Daphnia at the 31.3 mg/L dose level following 48-hours of exposure. No immobility was observed in the 15.6 mg/L dose level or the water control during the study.

The information derived from these preliminary tests were used to set the range of concentrations for the definitive test and supported the decision to conduct the definitive study under static-renewal conditions.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The acute toxicity of n-propyl propionate (EC50) to the daphnid (Daphnia magna), over a 48-hour static-renewal exposure period was 37.8 mg/L.
The 48-hour NOEC was 17.5 mg/L and was determined based on biological interpretation of the data and the highest exposure level exhibiting no Daphnia immobility.
Executive summary:

The acute toxicity study was conducted with two groups of ten Daphnia exposed to nominal test concentrations of 0 (water control), 6.25, 12.5, 25.0, 50.0, 100, and 200 mg n- propyl propionate/L, over a 48-hour static-renewal exposure period.

The mean measured n-Propyl Propionate concentrations were less than the lowest level quantified of 0.628 mg/L for the water control and 4.24, 8.75, 17.5, 35.9, 63.7, and 149 mg/L for the treatment solutions.

Observations were made at 24 and 48 hours for immobility (inability to swim within 15 seconds after gentle agitation of the test container). These data were statistically evaluated, where applicable, using mean measured n-propyl propionate concentrations.

The results are listed below:

The 24-hour EC50 was 59.6 mg/L, with a 95% confidence interval of 49.8–73.5 mg/L; the Probit slope was 5.5 with a 95%confidence interval of 3.2–7.7.

The 48-hour EC50 was 37.8 mg/L, with a 95% confidence interval of 31.6–44.6 mg/L; the Probit slope was 6.4 with a 95% confidence interval of 3.7–9.1.

The 48-hour NOEC was 17.5 mg/L and was determined based on biological interpretation of the data and the highest exposure level exhibiting no Daphnia immobility.