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Short-term toxicity to aquatic invertebrates

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Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
supporting study
Reason / purpose:
read-across source
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
24 mg/L
Basis for effect:
mobility
Remarks on result:
other: test result from read-across source CAS 25584-83-2 (Dow, 1992).
Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study without detailed documentation
Remarks:
GLP-guideline study performed by japanese authorities, no study report available for review.
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
GLP compliance:
yes
Specific details on test material used for the study:
- Name of test material (as cited in report): 2-hydroxylethyl acrylate
- Analytical purity: no data
Test organisms (species):
Daphnia magna
Test type:
static
Water media type:
freshwater
Total exposure duration:
48 h
Duration:
48 h
Dose descriptor:
LC50
Effect conc.:
5.2 mg/L
Conc. based on:
test mat.
Basis for effect:
mobility
Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
20 Dec 2012 to 4 Jan 2013
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Version / remarks:
13 April 2004
Deviations:
no
Qualifier:
according to
Guideline:
EPA OPPTS 850.1010 (Aquatic Invertebrate Acute Toxicity Test, Freshwater Daphnids)
Version / remarks:
1996
Deviations:
no
Qualifier:
according to
Guideline:
other: ASTM Standard E729-96: Standard Guide for Conducting Acute Toxicity Tests on Test Materials with Fishes, Macroinvertebrates and Amphibians (2007)
Deviations:
no
GLP compliance:
yes
Specific details on test material used for the study:
- Analytical purity: 97.41 %
- Lot/batch No.: A022C7C003
- Expiration date of the lot/batch: July 12, 2013
Analytical monitoring:
yes
Details on sampling:
Samples were collected from one test chamber of each treatment and control group 5 days prior to the start of the test after conditioning the diluter for approximately 1 day. Samples also were collected from alternating replicate test chambers in each treatment and control group at the beginning of the test and at 48 hours (± 1 hour) to measure concentrations of the test substance. An additional set of samples was taken at 48 hours and was stored refrigerated for future analysis. The samples were collected from mid-depth, placed in glass vials, and processed immediately for analysis.
Vehicle:
yes
Remarks:
dimethylformamide
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Individual stock solutions were prepared for each of the five concentrations tested. A primary stock solution was prepared by mixing a calculated amount of test substance into HPLC-grade dimethylformamide (DMF) at a nominal concentration of 300 mg /mL. Four secondary stock solutions were prepared in DMF at nominal concentrations of 39, 65, 110 and 180 mg/mL by proportional dilution of the primary stock. The stock solutions were mixed by inversion and appeared clear and colorless. Stock solutions were stored refrigerated in glass amber bottles with Teflon®-lined lids, and aliquots of each stock were placed in the syringe every 1-2 days during the study.
The five test substance stock solutions were injected into the diluter mixing chambers at a rate of 15.5 μL/minute where they were mixed with dilution water delivered at a rate of 155 mL/minute to achieve the desired test concentrations. The negative control received dilution water only. The solvent control was prepared by delivering HPLC-grade DMF to the mixing chamber for the solvent control.
- Chemical name of vehicle: dimethylformamide (DMF)
- Concentration of vehicle in test medium (final test solution): 0.1 mL/L
- Evidence of undissolved material: The test solutions in the mixing chambers and test chambers appeared clear and colorless during the test, with no evidence of precipitation observed in any control or treatment solution.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM:
- Strain: Daphnia magna
- Source: Wildlife International Cultures, Easton, Maryland 21601
- Age at study initiation: Neonates < 24 hours old
- Method of breeding: The four adult daphnids used to supply neonates for the test were held for at least 21 daysprior to collection of the juveniles for testing, and had each produced at least one previous brood. Adult daphnids in the culture had produced an average of at least three young per adult per day over the 7-day period prior to the test.
- Feeding during test: Neonates were not fed during the test

ACCLIMATION
- Acclimation period: 2 weeks
- Acclimation conditions: same as test
- Temperature: 19.5 to 20.8 °C
- pH: 8.1 to 8.5
- Oxygen concentration: >7.5 mg/L (≥82% of saturation)
- Type and amount of food: a mixture of yeast, cereal grass media and trout chow (YCT), a suspension of the freshwater green alga, Pseudokirchneriella subcapitata as well as a suspension of combined vitamin stock solution. The adults were fed prior to test initiation.
- Feeding frequency: daily
- Health during acclimation: No, the adults showed no signs of disease or stress and no ephippia were produced during the holding period.
Test type:
flow-through
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Post exposure observation period:
Not relevant
Hardness:
132 mg/L (as CaCO3)
Test temperature:
19.8 - 20.1 °C
pH:
8.0 - 8.1
Dissolved oxygen:
7.2 - 8.4 mg/L
Salinity:
no data
Conductivity:
338 µS/cm
Nominal and measured concentrations:
- Nominal concentrations: 0 (control), 0 (vehicle control), 3.9, 6.5, 11, 18, 30 mg/L
- Measured concentrations: -, -, 3.4, 6.2, 10, 17 and 29 mg/L
Details on test conditions:
TEST SYSTEM
- Material, size, headspace, fill volume of test vessel: 25-L stainless steel aquaria filled with approximately 22 L of test water. The depth of the test water in a representative chamber was 28.0 cm. Each test chamber contained one test compartment constructed from a glass beaker approximately 6.5 cm in diameter and 12 cm in height, with nylon screen attached to two holes on the sides of the beaker. The depth of the test water in a representative compartment was 8.5 cm.
- Type of flow-through: continuous-flow diluter; Syringe pumps (Harvard Apparatus, Massachusetts) were used to deliver test substance stock solutions or solvent to impartially assigned mixing chambers where the stocks or solvent were mixed with dilution water prior to delivery to the test chambers. The flow of dilution water into each mixing chamber was controlled using rotameters and was adjusted to provide approximately 5 volume additions of test water in each test chamber per day. After mixing, the flow from each mixing chamber was split to deliver test water to two replicate test chambers.
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 2
- No. of vessels per vehicle control (replicates): 2
- Feeding during test: no

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: The water used for culturing and testing was freshwater obtained from a well approximately 40 meters deep located on the Wildlife International site. The well water was passed through a sand filter to remove particles greater than approximately 25 µm, and pumped into a 37,800-L storage tank where the water was aerated with spray nozzles. Prior to use, the water was filtered to 0.45 µm to remove fine particles and was passed through an ultraviolet (UV) sterilizer.
- Total organic carbon: 1.1 mg C/L
- Metals: according to OECD guideline
- Pesticides: according to OECD guideline
- Alkalinity: 178 mg/L as CaCO3
- Culture medium different from test medium: no

OTHER TEST CONDITIONS
- Photoperiod: 16 hours of light and 8 hours of darkness (a 30-minute transition period of low light intensity was provided when lights went on and off to avoid sudden changes in lighting)
- Light intensity: 453 lux
- Light type: Ambient laboratory light was used to illuminate the test systems. Fluorescent light bulbs that emit wavelengths similar to natural sunlight were used.

EFFECT PARAMETERS MEASURED:
All organisms were observed periodically to determine the number of immobile organisms in each treatment group. Immobility was defined as a lack of movement by the organism except for minor activity of the appendages. The numbers of individuals exhibiting signs of toxicity or abnormal behavior also were evaluated. Observations were made approximately 3, 24 and 48 hours after test initiation.
Reference substance (positive control):
no
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
9.3 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 8.2 - 10.6 mg/L
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
3.4 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
- Behavioural abnormalities: Percent immobility at test termination in the 3.4, 6.2, 10, 17 and 29 mg/L mean measured treatment groups was 0, 5, 60, 100 and 100%, respectively.
- Other biological observations: Some daphnids in the negative control, solvent control and in the 3.4, 6.2, 10, 17 and 29 mg/L treatment groups were observed trapped at the water’s surface during the test. However, these daphnids appeared normal after being gently submerged. Lethargy was also observed in the 10 mg/L mean measured treatment group at test termination.
- Mortality of control: No
- Other adverse effects control: No
- Any observations that might cause a difference between measured and nominal values: The test solutions in the mixing chambers and test chambers appeared clear and colorless during the test, with no evidence of precipitation observed in any control or treatment solution.
Results with reference substance (positive control):
No data
Reported statistics and error estimates:
The immobility data were analyzed using the computer program of C. E. Stephan. The program was designed to calculate the EC50 value and the 95% confidence interval by probit analysis, the moving average method, and binomial probability with nonlinear interpolation. In this study, probit analysis was used to calculate the 24-and 48-hour EC50 values and 95% confidence intervals. The no-immobility concentration and NOEC, were determined by visual interpretation of the immobility and observation data.

Table: Cumulative Immobility

Mean measured concentration (mg/L)

Replicate

24 hours

48 hours

Percent Immobile

Number of Immobile

Number of Immobile

Negative Control

A

0

0

0

B

0

0

Solvent Control

A

0

0

0

B

0

0

 3.4

A

0

0

0

B

0

0

 6.2

A

0

1

5

B

0

0

10

A

4

7

60

B

2

5

17

A

6

10

100

B

7

10

29

A

10

10

100

B

10

10

 

ADDITIONAL EFFECT VALUE

24-h EC50 value: 13.4 mg/L (95% C.L.: 11.5 - 15.7 mg/L)

Validity criteria fulfilled:
yes
Remarks:
see 'Any other information on materials and methods incl. tables'.

Description of key information

The 48-h EC50 value is 9.3 mg/L in aquatic invertebrates (Daphnia magna).

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
9.3 mg/L

Additional information

Two studies are available that assessed the acute toxicity of 2-hydroxyethyl acrylate to aquatic invertebrates. Further, data of a close structural analogue (CAS 25584-83-2) is available and used as supporting information.

In the first study, the acute toxicity was determined according to OECD TG 202 and in compliance with GLP criteria (Wildlife International, 2013). In this study, daphnids (D. magna, 20 per concentration) were exposed to nominal concentrations of 0 (control), 0 (vehicle control), 3.9, 6.5, 11, 18, 30 mg/L for 48 hours under flow-through conditions (5 volume additions of test water in each test chamber per day). Analytical confirmation of nominal test concentrations showed that all test concentrations remained within ±20% of nominal concentrations throughout the test. Nevertheless, effect concentrations are expressed as measured (arithmetic mean). Immobilization was recorded after 3, 24 and 48 hours exposure. Percent immobility at test termination in the 3.4, 6.2, 10, 17 and 29 mg/L mean measured treatment groups was 0, 5, 60, 100 and 100% after 48 hours exposure, respectively. Based on these results, the 48-h EC50 was determined to be 9.3 mg/L.

In another study according to OECD TG 202, an EC50 of 5.2 mg/L based on measured concentrations was determined for Daphnia magna after 48 hours of exposure (MOE, 1998). Although no detailed test report is available, all tests from the Japanese Authorities are performed according to OECD guidelines and GLP.

These results are supported by data from the structural analogue 2-hydroxypropyl acrylate (2-HPA). In an acute toxicity study conducted according to OECD guideline 202 in Daphnia magna with 2-HPA, an EC50 of 24 mg/L based on nominal test concentrations was determined (Dow 1992).

Overall, the effect value of 48-h EC50 value of 9.3 mg/L was selected as key value for the chemical safety assessment, as it is considered the most reliable result (derived in a GLP-compliant study that followed standard guidelines, the daphnids in this study were exposed under flow-through condtitions and the effect value is based on measured concentrations).