butanedioic acid, 2-octenyl

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: This was a well-conducted study compliant with the OECD guideline as well as good laboratory practices.

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 850.1010 (Aquatic Invertebrate Acute Toxicity Test, Freshwater Daphnids)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

To confirm octenylsuccinic acid concentrations, and associated stability over the course of the exposure, the collected samples were analyzed by high pressure liquid chromatography/mass spectrometry (HPLC/MS). All test solutions were analyzed within 24 hours of preparation; therefore, no stability assessment was required.

The bulk exposure solutions were sampled for analytical confirmation of test material. At test initiation (0 hours), single aliquots (~5 ml) of lab dilution water (LDW) control bulk exposure solution was collected using a glass pipette and transferred to a 20 ml vial. At test initiation, four aliquots (~5 ml) from the 1000 mg/L bulk exposure solution were collected from the top, middle, and bottom of its container to evaluate homogeneity.

The contents of daphnid test vessels were pooled at exposure termination (48 hours) to provide one composite sample at each exposure concentration for analytical confirmation. Aliquots (~2 ml) were collected using a glass pipette and transferred to 20 ml glass vials. Pooled samples were vortex-mixed.

Samples were diluted to an acceptable analysis range with acetonitrile. These samles were analyzed by HPLC/MS-MS. The concentrations of Octenylsuccinic acid were quantified by using external standard calibration, and reported concentrations were not corrected for purity of the test material.

Vehicle:

no

Details on test solutions:

The test solution was prepared via direct addition of the test material to LDW to create a bulk test solution. An aliquot containing 1000 mg
octenylsuccinic acid (no adjustment for purity) was added to a 1-L volumetric flask filled to volume with LDW. The flask was then inverted and shaken until the solution appeared homogenous. Prior to pouring off into individual test vessels, the bulk test solution was pH adjusted utilizing 1N sodium
hydroxide and 1 N hydrochloric acid (initial pH = 3.5; final pH = 8.0). The bulk test solution and water control were clear and colorless.

Test solutions were utilized on the same day as preparation; thus, assessment of stability of the test solution was not required. The dispersal of the
test material in the surrounding medium was considered to represent the most probable route of exposure in the environment.

Test organisms (species):

Daphnia magna

Details on test organisms:

The test organism was the freshwater daphnid, Daphnia magna, from in-house cultures initially obtained from Aquatic BioSystems, Inc. Fort Collins, Colorado. This species is widely accepted and recommended for toxicity testing by the test guidelines. Daphnid neonates less than 24-hours old
from a laboratory-reared culture were used as the test organisms. Neonates were only used from daphnids which have had at least 3 broods. The
day before neonates were needed for testing (< 24 hours prior to test initiation), neonates within the culture vessels were removed and discarded
leaving only adult daphnids in the vessels. On the following day, neonates produced overnight in these same culture vessels were again removed
from the vessels and placed into a glass beaker containing lab dilution water (LDW). These neonates (< 24 hours old) were held in an incubator until used for the study.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Post exposure observation period:

Not applicable

Hardness:

Water control = 52 mg CaCO3/L
Limit concentration (1000 mg/L nominal) = 50 mg CaCO3/L

Test temperature:

Temperatures ranged from 19-20 °C.

pH:

pH ranged from 7.6-8.0.

Dissolved oxygen:

Dissolved oxygen levels ranged from 8.6-8.8 mg/L (97-99% air saturation).

Salinity:

Not applicable

Nominal and measured concentrations:

Nominal concentrations = 0 (water control), 1000 mg/L
Measured concentrations = < lowest limit quantified, 736 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 50 ml beaker
-Fill volume: 40 ml
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: ake Huron water supplied to The Dow Chemical Company (TERC Laboratory) by the City of Midland Water
Treatment Plant. The water was obtained from the upper Saginaw Bay of Lake Huron off Whitestone Point and was limed and flocculated with ferric
chloride. Before use in the laboratory, the water was sand-filtered, pH-adjusted with gaseous CO2, carbon-filtered, and UV-irradiated. The water is typically monitored weekly for pH, alkalinity, hardness and conductivity. Periodically, the water is monitored for total organic carbon (TOC), total suspended solids (TSS), and selected inorganic and organic compounds. Results from the most recent analysis of the dilution water indicated that TOC was 0.95 mg/L, TSS was < 3 mg/L, and concentrations of contaminants were below levels that may have interfered with the results of this test.


OTHER TEST CONDITIONS
- Adjustment of pH: the bulk test solution was pH adjusted utilizing 1N sodium hydroxide and 1 N hydrochloric acid (initial pH = 3.5; final pH = 8.0).
- Photoperiod: 16 hrs light/8 hrs dark
- Light intensity: 523-589 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Daphnids were observed for immobility (inability to swim within
approximately 15 seconds after gentle agitation of the test vessel) at approximately 24 and 48 hours of exposure (± 1 hour from exposure
initiation). Any sublethal effects (abnormal behavior or appearance) were recorded.

TEST CONCENTRATIONS
- Test concentrations: 0, 1000 mg/L (nominal)
- Range finding study
- Test concentrations: 0 (water control), 10, 25, and 100 % of a 1000 mg octenylsuccinic acid/L saturated solution. Test solutions were prepared from a 1000 mg octenylsuccinic acid/L saturated solution (equal to the high test concentration). An aliquot containing 30,000 mg (30 g) octenylsuccinic acid (no adjustment for purity) was added to a 40-L glass carboy containing 30 L of LDW. The mixture was stirred on a magnetic stir plate
and was subsequently filtered (0.45 μm) creating a saturated solution. The mixture was slightly cloudy white with foam/bubbles on the surface prior to filtration. After filtration, the resulting saturated solution was pH adjusted with 1N sodium hydroxide and 1N hydrochloric acid (initial pH = 3.2; final pH = 7.6). Prior to pH adjustment, the saturated solution was clear and colorless with foam/bubbles at the surface. Following pH adjustment, the solution was clear and colorless.
- Results used to determine the conditions for the definitive study: Following 48 hours of exposure, no immobility or sublethal effects were observed in any of the treatment levels, including the water control. Based on information from the range-finding test, a single nominal exposure
concentration of 1000 mg octenylsuccinic acid/L, replicated four times, was used in the definitive study (limit test). Four replicate test vessels of LDW served as the water control.

Reference substance (positive control):

no

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

> 736 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 736 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

736 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

No immobility or sublethal effects (change in daphnid behavior or appearance) were observed in the water control or the 736 mg octenylsuccinic
acid/L test concentration over the course of the exposure.

Results with reference substance (positive control):

Not applicable

Reported statistics and error estimates:

Due to the absence of any immobility observed in the 48-hour exposure, the 24- and 48- hour EC50 values (the concentrations estimated to
immobilize 50% of the daphnids after 24 and 48 hours of exposure, respectively) were empirically determined to be greater than the highest (limit) concentration tested. Furthermore, since there was also an absence of sublethal effects (changes in daphnid behavior or appearance) observed in the test, the NOEC was empirically determined to be equal to the highest (limit) concentration tested.

Validity criteria fulfilled:

yes

Conclusions:

The acute toxicity values for Daphnia magna exposed to octenylsuccinic acid, over a 48-hour static exposure period and based on mean
measured concentrations, were as follows:
• 24-, and 48-hour EC50 values: >736 mg/L (limit concentration tested)
• The 48-hour NOEC: 736 mg/L (limit concentration tested)
Based on these results and the observed solubility behavior under the conditions tested, the test material can be regarded as not acutely toxic to
Daphnia magna at its solubility limit (~ 736 mg/L).

Executive summary:

The purpose of this study was to assess the potential effects of octenylsuccinic acid to the freshwater cladoceran, Daphnia magna. The study was conducted as a limit test with four replicate vessels of five daphnids per test level exposed to nominal test concentrations of 0 (water control) and 1000 mg octenylsuccinic acid/L, over a 48-hour static exposure period. Observations were made at 24 and 48 hours (±1 hour from exposure initiation) for daphnid immobility (inability to swim within approximately 15 seconds after gentle agitation of the test container) and any changes in behavior or appearance. Temperatures during the exposure period ranged from 19-20 °C. Dissolved oxygen levels ranged from 8.6-8.8 mg/L (97-99% air saturation). The pH ranged from 7.6-8.0 and the light intensity ranged from 523-589 lux.

Test solutions were analyzed at test initiation and exposure termination by high pressure liquid chromatography/mass spectrometry (HPLC/MS). None of the analyses of the water control exhibited a concentration exceeding lower limit of quantitation (LLQ) equivalent to 4.16 mg octenylsuccinic acid/L. Measured concentrations were < LLQ for the 0 (water control) and ranged from 585 to 887 mg/L for the 1000 mg octenylsuccinic acid/L nominal test solutions; the resulting mean measured concentration was 736 mg octenylsuccinic acid/L. These analytical results indicate that the test material was stable in the exposure medium over the 48-hour exposure period, and that the test material was not fully soluble at the 1,000 mg/L nominal concentration. The data collected were used to calculate the 24 - and 48-hour EC50 values (the concentrations estimated to immobilize 50% of the daphnids after 24 and 48 hours of exposure, respectively) and a 48-hour no-observed-effect concentration (NOEC). The acute toxicity values for the daphnid (D. magna) exposed to octenylsuccinic acid over a 48-hour static exposure period and based on mean measured concentrations were as follows:

• 24- and 48-hour EC50 : >736 mg/L (limit concentration tested)

• 48-hour NOEC: 736 mg/L (limit concentration tested).

Based on these results and the observed solubility behavior under the conditions tested, the test material can be regarded as not acutely toxic to Daphnia magna at its solubility limit (~ 736 mg/L).

Description of key information

A single study (Reliability 1) of the short-term toxicity of octenylsuccinic acid to aquatic invertebrates is available. The GLP compliant study was performed according to the OECD 202 testing guideline. The reported 48-hour EC50 value for immobilization was greater than the highest exposure concentration, 736 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

736 mg/L

Additional information

In a single acute toxicity study with the freshwater cladoceranDaphnia magna, organisms were exposed to nominal concentrations of 0 and 1000 mg octenylsuccinic acid/L (limit test) for 48 hours under static conditions. Test solutions were analyzed for octenylsuccinic acid concentrations by high performance liquid chromatography/mass spectrometry at test initiation and termination. The resulting 48-hour EC50 value for immobilization based on mean measured concentration was greater than 736 mg/L (i.e., 50% immobility not observed at highest concentration tested), with a no-observed-effect concentration (NOEC) of 736 mg/L.