Butyl propionate

Short-term toxicity to fish

Administrative data

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2005

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study was conducted according to OECD TG 203, EU Method C.1, EPA 797.1440 and in accordance with the Principles of Good Laboratory Practice (GLP)

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

reference to same study

Cross-reference 2

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2005

Report date:

2005

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.1 (Acute Toxicity for Fish)

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

other: EPA 797.1440

Deviations:

no

Principles of method if other than guideline:

not applicable

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Butyl propionate

EC Number:

209-669-5

EC Name:

Butyl propionate

Cas Number:

590-01-2

Molecular formula:

C7H14O2

IUPAC Name:

butyl propanoate

Details on test material:

- Name of test material (as cited in study report): UCAR n-butyl propionate
- Physical state: transparent colourless liquid
- Analytical purity: 99.7%
- Lot/batch No.: 369856

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: 0.653, 1.33, 2.19, 3.50, 5.91, and 10.0 mg/L.
- Sampling method: Replicate test solutions as well as the mixing cell were sampled for analytical confirmation of n-butyl propionate concentrations on days 0 and 4 of the study. To assess analytical method precision and solution homogeneity, three additional samples were taken on day 0 from representative 0.653 and 10.0 mg/L test solutions and analyzed along with day 0 samples

Test solutions

Vehicle:

no

Details on test solutions:

For the definitive test, two replicate aquaria were prepared in laboratory dilution water (LDW) at each nominal exposure concentration of 0.653, 1.33, 2.19, 3.50, 5.91, and 10.0 mg/L. In addition, two replicate aquaria of control water (LDW with no test material added and referred to as water control) were prepared. Aquaria were replenished on a regular intermittent cycle (approximately every 30 minutes) with test solutions delivered from a flow-through proportional diluter, which was fortified from a glass vessel filled with undiluted test material.

Test organisms

Test organisms (species):

Oncorhynchus mykiss (previous name: Salmo gairdneri)

Details on test organisms:

TEST ORGANISM
- Common name: rainbow trout
- Strain: Oncorhynchus mykiss
- Source: The fish were obtained as juveniles from Thomas Fish Company, Anderson, California (Lot # RT022505).
- Age at study initiation: juveniles
- Length at study initiation (length definition, mean, range and SD): 4.4 ± 0.3 cm in total length
- Weight at study initiation (mean and range, SD): 0.731 ± 0.134 g in mass (post-exposure)
- Feeding during test: no

ACCLIMATION
- Acclimation period: more than 14 days
- Acclimation conditions (same as test or not): yes
- Type and amount of food: During holding, the fish received a standard diet (Aquatic Diet Number 1 Lot #233796, Harlan-Teklad, Madison, Wisconsin) typica lly once daily when not fasted for testing.
- Health during acclimation (any mortality observed): mortality did not exceed five percent of the population in the 7 days before testing.

Study design

Test type:

flow-through

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Post exposure observation period:

not applicable

Test conditions

Hardness:

62-76 mg/l

Test temperature:

13-14 °C

pH:

7.5-7.8

Dissolved oxygen:

8.2-9.3 mg/l

Salinity:

not applicable

Nominal and measured concentrations:

Nominal test concentrations - 0 (water control), 0.653, 1.33, 2.19, 3.50, 5.91, and 10.0 mg n-butyl propionate/L
Measured (mean) test concentrations - 0 (water control), 0.562, 1.30, 1.92, 3.22, 5.60, and 9.45 mg n-butyl propionate/L

Details on test conditions:

TEST SYSTEM
- Test vessel:Test aquaria were constructed of double-strength glass held together with clear silicone adhesive and measured approximately 30 x 15.5 x 12.5 cm. Each vessel had a glass cover and a Nitex (Tetko, Elmsford, New York) screen-covered drain guard, which maintained a test volume of approximately 3.7 L. Each aquarium was uniquely labeled for identification purposes.
- Type of flow-through (proportional diluter): An intermittent- flow proportional diluter system was used to maintain constant exposure concentrations during the 4-day study period. This system was designed to deliver up to six test concentrations, a vehicle control, and a water control. The diluter was calibrated so that the concentration of the test substance in each treatment below the high concentration was approximately 60 percent of that in the next higher treatment level. The diluter operated as follows: a precision dosing system (Hamilton Company, Reno, Nevada MICROLAB 500 system) delivered a designated amount of test material from a glass vessel to the mixing chamber where it was mixed with lab dilution water and then distributed to toxicant cells. The mixing chamber was equipped with a recirculating pump that facilitated dissolution and mixing of the test material. When the diluter cycled, the test substance from each toxicant cell blended with water from its respective water cell and flowed into mixing/splitting chambers. Silicone delivery tubes with glass capillary tube exit ports from these chambers provided approximately 1 L of test solution to each of two replicate test aquaria. The mixing/splitting chambers were randomly positioned according to a computer-generated randomization on the diluter. The aquaria were positioned under these chambers on one tier, side-by-side, in a water trough. A thermostatic temperature controller maintained a water temperature of 13 ± 1°C in the trough. Diluter and laboratory lighting provided a 16-hour light/8- hour dark transitional photoperiod during testing. The diluter was calibrated prior to test initiation and averaged 12.4 volume turnovers in the test aquaria each 24-hour period during exposure.
- No. of organisms per vessel: ten fish/level (two replicate vessels with five fish per test level)
- No. of vessels per concentration (replicates): two replicate aquaria per dose level
- No. of vessels per control (replicates):
- Biomass loading rate: 1.0 g fish/l (average instantaneous biological rate)

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: The laboratory dilution water (LDW) was Lake Huron water supplied to The Dow Chemical Company by the City of Midland Water Treatment Plant. The water was obtained from the upper Saginaw Bay of Lake Huron near Whitestone Point and was limed and flocculated with ferric chloride. The water is pumped to the laboratory prior to treatment for municipal use. Before use in the laboratory, the water was sand-filtered, pH adjusted with gaseous CO2, carbon-filtered, and UV- irradiated. Refer to attachments for further details

EFFECT PARAMETERS MEASURED: The fish were observed after 24, 48, 72, and 96 hours of exposure for mortality (no response to touching of the caudal peduncle and no opercula movement) and sublethal effects.

TEST CONCENTRATIONS
- Range finding study - In the probe study, one replicate of five fish per dose level was exposed to nominal concentrations of 0 (water control), 3.89, 6.48, 10.8, 18.0, 30.0, and 50.0 mg/L, over a 96-hour flow-through exposure period. Flow-through conditions were used due to the volatility of n-butyl propionate in aqueous solution. Following 96- hours of exposure, fish mortality was observed in 20% of the fish at the 3.89 mg/L test level, 60% of the fish at the 6.48 mg/L test level, and 100% of the fish at the 10.8 mg/L and above test levels. Sublethal effects were observed down through the 3.89 mg/L test level; no sublethal effects or mortality was observed in the control. During the study, the diluter feedstock (undiluted test material) vessel emptied between the 72- and 96- hour observation periods and caused a decline in the exposure concentrations over the final 24-hour exposure period. Therefore, the mortality and sublethal effects observed at 96-hours (test termination) may be slightly less than if the exposure concentrations were maintained during the entire 96-hour test. However, the
information from this test was sufficient to determine the range of concentrations for the definitive test.
Analytical chemistry confirmation of test solution concentrations showed that percent recovery of target (nominal) concentrations ranged from approximately 76% to 98% on day 0 and 45 to 55% at test termination. This decline in exposure concentration from day 0 to test termination was most likely a result of the reduction of test material added during the final day of the study (emptying of feedstock) rather than volatilization of the test material.
Based on this information, the following target (nominal) concentrations for the definitive test were selected: 0 (water control) 0.562, 1.30, 1.92, 3.22, 5.60, 9.45 mg/L, corrected based on the diluter system’s calibration results.
- Results used to determine the conditions for the definitive study: yes

Reference substance (positive control):

no

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

6.89 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks on result:

other: 6.22 - 7.63 mg/l

Effect concentrations 2

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

1.3 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

other: highest concentration tested exhibiting no fish mortality or sublethal effects

Details on results:

The mean (+ standard deviation) length and weight of the water control fish was 4.3 0.1 cm and 0.673 0.0849 g, respectively. The mean length and weight of all surviving n-butyl propionate exposed fish was 4.4 0.3 cm and 0.743 0.140 g, respectively, indicating that fish used in this study were of a similar size class. Pooled length and weight means of all surviving fish combined was 4.4 0.3 cm and 0.731 0.134 g, respectively. The resulting average instantaneous biological loading rate, calculated as: [(mean fish weight of 0.731 g 5 fish per vessel)/3.7 L of solution per vessel], was 1.0- g fish/L of test. The average loading rate based on total solution flow in a 24- hour period calculated as: [(mean fish weight of 0.731 g 5 fish per vessel)/(average of 45.5 diluter cycles per day 1.007 L mean measured flow per vessel per cycle)], was 0.08-g fish/L/day. All biological results were expressed in terms of mean measured n-butyl propionate concentrations.

Sublethal effects were observed as far down as the 1.92 mg/L test level during the conduct of this 96-hour exposure study. Sublethal effects observed included partial/complete loss of equilibrium and lethargy. No sublethal effects were observed in the 1.30 mg/L and below test levels or in the control solution during the conduct of this study.

Following 24 hours of exposure, no mortality was observed at any test level. Following 48 hours of exposure, mortality was observed in 70% of the fish at the 9.45 mg/L test level. Following 72 hours of exposure, mortality was observed in 90% of the fish at the 9.45 mg/L test level. At test termination (96- hours of exposure) the total percent fish mortality observed was 10% and 100% at the 5.60 and 9.45 mg/L test levels, respectively. No fish mortality was observed at the 3.22 mg/L and below test levels or in the control solution during the conduct of this study.

Under the conditions of the study, the 96-hour LC50 of UCAR n-butyl propionate to rainbow trout (Oncorhynchus mykiss) was 6.89 mg/l with a 95% confidence interval of 6.22-7.63 mg/L and the 96-hour NOEC, based on biological interpretation of the data, was 1.30 mg/L.

Results with reference substance (positive control):

not applicable

Reported statistics and error estimates:

An appropriate computer program was used to calculate the LC50 values and corresponding 95% confidence intervals when possible. Two statistical methods are available: Probit Program, Version 1.5, U.S. EPA, 1994 and Trimmed Spearman-Karber (TSK) Program, Version 1.5, U.S. EPA, 1994. The order of preference used to select the method for reporting LC50 values is Probit analysis followed by trimmed Spearman- Karber. However, the appropriateness of a given method is determined by the concentration-response data, e.g., the number of concentrations resulting in mortality between 0 and 100 percent. The NOEC was empirically determined based on biological interpretation of the data and/or the highest concentration tested exhibiting no fish mortality or sublethal effects.

Any other information on results incl. tables

Sublethal observations / clinical signs:

Results from the day 0 analysis, as the average of measured concentrations from two replicate test solutions per dose level, ranged from 95.6 to 105% of the target concentrations. The day 4 measured concentrations were 76.6 to 93.1% of target for the average of two replicate test solution values per dose level. A study average was also calculated for each dose level by averaging the day 0 and day 4 average measured concentrations. The study average values ranged from 86.1 to 94.8% of target concentrations.

 

Samples collected from the mix cell (target concentration of 10.0 mg/L) on days 0 and 4 of the study afforded measured concentrations of 15.8 and 12.6 mg/L, respectively. None of the analyses of the water controls exhibited a peak eluting at the retention time of n-butyl propionate at a concentration exceeding the lowest level quantified (LLQ) equivalent to 0.452 mg n-butyl propionate/L LDW.

 

The variability associated with the analytical method as well as solution homogeneity was assessed on day 0 of the study. Four replicate samples were collected from representative 0.653 and 10.0 mg/L test solutions. Four repeated measurements (4 samples x 1 injection/sample) resulted in percent relative standard deviation (RSD) values of 9.47 and 5.42% for the low and high dose levels, respectively. The GC/FID instrumentation exhibited a linear response over the concentration ranges analyzed. The LLQ was set at 0.452 mg n-butyl propionate/L LDW based on the concentration of the lowest standard analyzed for analysis of the day 0 samples times the dilution factor.

 

Dissolved oxygen levels ranged from 8.2-9.3 mg/L (80-90% oxygen saturation) over the 96-hour exposure period. Temperature measured daily from the individual test vessels and continuously measured from one replicate test vessel (1.92 mg/L replicate A, mean measured) ranged from 13-

14°C and maintained within 13±1°C throughout the study. The pH ranged from 7.5-7.8 and the light intensity ranged from 739-956 lux.

 

Water quality parameters such as hardness, alkalinity, conductivity, and residual chlorine were measured from test solution samples collected from the splitter cells on day 0 and 4 from the control water and the highest treatment solution with surviving fish (9.45 mg/L day-0 test solution and 5.60 mg/L day-4 test solution, mean measured). Hardness (as CaCO3) ranged from 62-74 mg/L in the control water and 66-76 mg/L in the treatment solutions. Alkalinity (as CaCO3) ranged from 23-24 mg/L in the control water and 34 -38 mg/L in the treatment solutions. Conductivity ranged from 172-175mmhos/cm in the control water and 160-167mmhos/cm in the treatment solutions. Residual chlorine was < 10 ppb (instrument’s limit of detection) in all solutions measured.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

Under the conditions of the study, the 96-hour LC50 of UCAR n-butyl propionate to rainbow trout (Oncorhynchus mykiss) was 6.89 mg/l with a 95% confidence interval of 6.22-7.63 mg/L and the 96-hour NOEC, based on biological interpretation of the data, was 1.30 mg/L.

Executive summary:

The purpose of this study was to evaluate the acute toxicity of n-butyl propionate (propionic acid, n-butyl ester) to the rainbow trout (Oncorhynchus mykiss),over a 96-hour flow-through exposure period. These data were used to calculate 24-, 48-, 72-, and 96-hour LC50values (the concentration that is lethal to 50 percent of the test population during a defined period) and a 96-hour no-observed-effect concentration or NOEC.

 

The study was conducted with two groups of five fish exposed to nominal test concentrations of 0 (water control), 0.653, 1.33, 2.19, 3.50, 5.91, and 10.0 mg n-butyl propionate/L, over a 96-hour flow-through exposure period. Observations were made every 24 hours for mortality (no response to contact with the caudal peduncle and no opercula movement) and sublethal effects.

 

All replicate test solutions were sampled for analytical confirmation of n-butyl propionate concentrations on days 0 and 4 of the study. The collected samples were analyzed by gas chromatography with flame ionization detection (GC/FID). Test solution concentrations (average of measured concentrations from two replicate test solutions per dose level) ranged from 95.6 to 105% of the target concentrations on day 0 and 76.6 to 93.1% of target on day 4. The stud y average values ranged from 86.1 to 94.8% of target concentrations. The mean measured concentrations for the study were less than the lowest level quantified of 0.452 mg/L for the water control and 0.562, 1.30, 1.92, 3.22, 5.60, and 9.45 mg/L for the treatment solutions.

 

Under the conditions of the study, the 96-hour LC50 of UCAR n-butyl propionate to rainbow trout (Oncorhynchus mykiss) was 6.89 mg/l with a 95% confidence interval of 6.22-7.63 mg/L and the 96-hour NOEC, based on biological interpretation of the data, was 1.30 mg/L.