Ethyl [2-(4-phenoxyphenoxy)ethyl]carbamate

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

29 Jul 1992 to 31 Jul 1992

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EPA OPP 72-2 (Aquatic Invertebrate Acute Toxicity Test)

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

Analytical determination of test substance concentration from the definitive test was performed on samples from one of the replicate test vessels of each concentration at the beginning and end of the test. These samples were stored in 125 mL plastic bottles and refrigerated. Samples were transferred to the third party laboratory. Samples were shipped by overnight courier in an ice chest with freezer packs.

Vehicle:

yes

Remarks:

Acetone

Details on test solutions:

A stock with a concentration of 25,000 mg/L was prepared by combining 12.781 g of test substance with dilution water in a class A volumetric flask and adjusting the final volume to 500 mL with acetone. The solution was mixed thoroughly. Appropriate amounts of the stock solution were added directly to dilution water by proportional diluter (0.3 mL of stock solution was combined with 3010 mL of water during each diluter cycle = 2.5 mg/L test substance) and this diluter toxicant cell solution was mixed by a high shear pump with a teflon head. Nominal concentrations of the active ingredient 0 (control), 0.38, 0.62, 1.0, 1.5, and 2.5 mg/L.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: water flea
- Age at study initiation: juvenile
- Feeding: freshwater algae and a yeast/trout chow slurry daily before the test

Test type:

flow-through

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

164 mg CaCO3/L

Test temperature:

20 ± 1°C

pH:

8.3

Dissolved oxygen:

6.9 to 8.5 mg/L

Conductivity:

620 µmhos/cm

Nominal and measured concentrations:

Nominal concentrations: 0.38, 0.62, 1.0, 1.5, and 2.5 mg/L
Measured concentrations: 0.16, 0.26, 0.39, 0.60, and 0.84 mg/L. Measured concentrations were 32 to 46% of nominal values (reflecting the fact that the test concentrations were above the water solubility of the test substance in the dilution water)

Details on test conditions:

TEST SYSTEM
- Test vessel: 20 liter glass aquaria that contained 15 liters of test solution (water depth was approximately 19 cm). Test organisms were exposed in chambers that consisted of a glass cylinder with
mesh silicone cemented to the bottom. These cages were suspended within each test vessel. Test vessels were randomly arranged in a water bath during the 48 hour test (a random numbers table was used to select the location of each vessel).
- Type of flow-through: intermittent flow proportional diluter
- Renewal rate of test solution: 5 media exchanges/24 h in each test vessel
- 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

OTHER TEST CONDITIONS
- Photoperiod: 16 hours light and 8 hours dark
- Light intensity: 34 foot candles

EFFECT PARAMETERS MEASURED:
The number of surviving organisms and the occurrence of sublethal effects (lethargy and immobilization) were visually and recorded after 24 and 48 hours.

VEHICLE CONTROL PERFORMED: yes

Reference substance (positive control):

no

Key result

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

0.6 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mortality

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

0.26 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mortality

Details on results:

- Mortality of control: Ninety five to one hundred percent survival occurred in the control and solvent control, and no sublethal effects were noted during the exposure period in either control.
- Any observations that might cause a difference between measured and nominal values: Insoluble material (white floating was noted in the diluter stock (2.5 mg/L nominal) throughout the test and insoluble material was not observed in any test vessel during the test. The 25,000 mg/L (nominal) stock solution had a mean measured concentration of 25,200 to 25,900 mg/L test substance. Nominal concentrations of the test substance were: 0.38, 0.62, 1.0, 1.5, and 2.5 mg/L Mean measured concentrations of the test substance in centrifuged test media were: 0.16, 0.26, 0.39, 0.60, and 0.84 mg/L. Measured concentrations were 32 to 46% of nominal values (reflecting the fact that the test concentrations were above the water solubility of the test substance in the dilution water)

Validity criteria fulfilled:

yes

Conclusions:

In an acute aquatic toxicity study with Daphnia conducted according to the EPA 72-2, exposure to the test substance resulted in a 48 hour EC50 of 0.60 mg/L with a 95 % confidence interval of 0.51 to 0.73 mg/L (the slope of the dose-response curve = 4.6). The 48 hour no observed effect concentration was 0.26 mg/L.

Executive summary:

The acute toxicity of the test substance to daphnid, Daphnia magna was tested in a study conducted according to the EPA 72-2 guideline and in compliance with GLP. The test was performed under flow-through conditions with five concentrations of test substance, a dilution water control, and a solvent control at a temperature of 20 ± 1°C. The dilution water was filtered dechlorinated tap water adjusted to a hardness of 160 to 180 mg/L. The test was performed at and above the apparent water solubility of the test substance as evidenced by the observation of white particles floating on the water surface in the diluter's toxicant mixing vessel (nominal concentration of the stock was 2.5 mg/L). Nominal concentrations of 0 mg/L (control and solvent control), 0.38, 0.62, 1.0, 1.5, and 2.5 mg/L. measured concentrations of in centrifuged test media were: (<0.02 mg/L, control and solvent control), 0.16, 0.26, 0.39, 0.60, and 0.84 mg/L and concentrations were stable during the 48 hour testing period. Mean measured concentrations were used for all calculations. Organisms used in the test were produced from in house cultures maintained and acclimated at the testing laboratory under test conditions. After 48 hours of exposure the control had an average wet weight (blotted dry) of 0.16 mg. All animals were in good condition at the beginning of the study. Exposure of daphnids to the test substance resulted in a 48 hour median lethal concentration EC50 of 0.60 mg/L, with a confidence interval of 0.51 to 0.73 mg/L. The 48-hour no observed effect concentration was 0.26 mg/L.

Reference 2

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

11 Sep 1992 to 15 Sep 1992

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EPA OPP 72-3 (Estuarine/Marine Fish, Mollusk, or Shrimp Acute Toxicity Test)

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

Analytical determination of test substance concentration from the definitive test was performed on samples from one of the replicate test vessels of each concentration at the beginning and end of the test. These samples were stored in 125 mL plastic bottles and refrigerated. Samples were transferred to a third party laboratory. Samples were shipped by overnight courier in an ice chest with freezer packs.

Vehicle:

yes

Remarks:

Acetone

Details on test solutions:

A stock with a concentration of 10000 mg/L was prepared by combining 5.1 g of test substance with dilution water in a class A volumetric flask and adjusting the final volume to 500 mL with acetone. The solution was mixed thoroughly. Appropriate amounts of the stock solution were added directly to dilution water by proportional diluter (0.3 mL of stock solution was combined with 3010 mL of water during each diluter cycle = 1 mg/L test substance) and this diluter toxicant cell solution was mixed by a high shear pump with a teflon head. Nominal concentrations of the active ingredient 0 (control), 0.15, 0.25, 0.4, 0.6, and 1 mg/L.

Test organisms (species):

Americamysis bahia (previous name: Mysidopsis bahia)

Details on test organisms:

TEST ORGANISM
- Age at study initiation: less than 24 h

ACCLIMATION
- Acclimation period: 10 days
- Health during acclimation: no mortalities or abnormalities observed

Test type:

flow-through

Water media type:

saltwater

Limit test:

no

Total exposure duration:

96 h

Test temperature:

21.4 - 22.4 °C

pH:

7.8 - 8.0

Dissolved oxygen:

7.3 - 8.6 mg/L

Salinity:

1.6 - 1.7 %

Nominal and measured concentrations:

Nominal concentrations: 0, 0.15, 0.25, 0.40, 0.60, and 1.0 mg/L
Mean measured concentrations: 0, 0.089, 0.14, 0.22, 0.34, 0.53 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 20 liter glass aquaria that contained 15 liters of test solution (water depth was approximately 18 cm) and mysids were confined in glass and Nitex screen cages suspended in each test vessel. Test vessels were randomly arranged in a water bath during the 96 hour test (a random numbers table was used to select the location of each vessel).
- Type of flow-through: intermittent-flow proportional diluter
- Renewal rate of test solution: 5.6 media exchanges/24 h
- 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

TEST MEDIUM / WATER PARAMETERS
- Salinity: 1.6 - 1.7 %


OTHER TEST CONDITIONS
- Photoperiod: 16 hours light, 8 hours dark with 15 minutes transition period
- Light intensity: 35 footcandles

EFFECT PARAMETERS MEASURED:
The number of surviving organisms and the occurence of sublethal effects were determined visually and 24, 48, 72, and 96 hours

VEHICLE CONTROL PERFORMED: yes

Reference substance (positive control):

no

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

0.35 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other: 95 % CI: 0.22 - 0.53 mg/L

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

0.22 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mortality

Details on results:

- Mortality of control: At least 95% survival occurred in the control and solvent control and no sublethal effects were noted during the exposure period in either control.
- Any observations that might cause a difference between measured and nominal values: Insoluble (white particles) was noted in the diluter stock solution (1.0 nominal concentration) and on the bottom of all non-control test vessels throughout the test.

Validity criteria fulfilled:

yes

Conclusions:

In an acute aquatic toxicity study performed in accordance with EPA 72-3, exposure of mysids to the test substance resulted in a 96 hour LC50 of 0.35 mg/L, with a 95% confidence interval of 0.22 to 0.53 (the slope of the dose-response curve could not be calculated from this data set). The 96 hour no observed effect concentration was 0.22 mg/L test substance.

Executive summary:

The acute toxicity of the test substance to the mysid, Mysidopsis bahia was tested in a study conducted following the EPA 72-3 guideline and in compliance with GLP. The test was performed under flow-through conditions with five concentrations of test substance, a dilution water control, and a solvent control at a temperature of 22 ± 1°C. The dilution water was filtered natural sea water adjusted to a salinity of 16 to 17 parts per thousand. The test was performed at and above the apparent water solubility of the test substance, as evidenced by the observation of white in the diluter's toxicant mixing vessel and all non-control test vessels (nominal concentration of the stock solution was 1.0 mg/L). Nominal concentrations of the test substance were: 0.15, 0.25, 0.40, 0.60, and 1.0 mg/L. Mean measured concentrations of the test substance in centrifuged test media were: 0.14, 0.22, 0.34, and 0.53 mg/L and concentrations were stable during the 96 hour testing period. Mean measured concentrations were used for all calculations. All organisms used in the test were produced by an in house culture that was maintained at test conditions for more than 10 days at the testing facility. After 96 hours of exposure the control organisms had an average wet weight (blotted dry) of 0.76 mg. All animals were in good condition at the beginning of the study. Exposure of mysids to the test substance resulted in a 96-hour lethal concentration (LC50) of 0.35 mg/L with a 95 % confidence interval of 0.22 to 0.53 mg/L. The 96-hour no observed effect concentration was 0.22 mg/L.

Reference 3

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EPA OPP 72-3 (Estuarine/Marine Fish, Mollusk, or Shrimp Acute Toxicity Test)

GLP compliance:

yes

Test organisms (species):

other aquatic mollusc: Crassostrea virginica

Test type:

flow-through

Water media type:

saltwater

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

0.52 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mortality

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

0.18 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

The measured concentrations were 0.18, 0.33, 0.46, 0.64 and 1.0 mg/L at test initiation (representing 25 - 33% of nominal), and 0.18, 0.30, 0.50, 0.68 and 1.1 mg/L at the end of exposure (representing 28-31% of nominal). Endpoints were based on mean measured concentrations, which is acceptable. Water quality parameters (pH, oxygen concentration, temperature and salinity) were in accordance with the EPA 72-3 guideline.

Table 1. The acute toxicity of the test substance to aquatic invertebrates.

Species	Test type and duration. (purity of test substance)	Actual concn. (as % of nominal)	EC50 in mg/L	NOEC mg/L
Crassostrea virginica(marine organism)	Flow-through 96 hours (97.8%)	25-33	96 h: 0.52(A)	96 h: 0.18(A)

(A) Based on mean measured concentrations

Validity criteria fulfilled:

yes

Conclusions:

In an acute aquatic toxicity test performed in accordance with EPA 72-3, exposure of oysters to the test substance resulted in a 96 hour median effective concentration of 0.52 mg/L test substance, with a 95 % confidence interval of 0.49 to 0.55 mg/L. The 96 hour no observed effect concentration was 0.18 mg/L.

Executive summary:

The acute toxicity of the test substance to the Crassostrea virginica, as judged by the deposition of new shell, was determined in the study performed following the EPA 72-3 guidance and in compliance with GLP. The test was performed under flow-through conditions with five concentrations of test substance, a dilution water control, and a solvent control at a temperature of 22±1°C. The dilution water was natural sea water. The test performed at and above the apparent water solubility of the test substance, as evidenced by the observation of white in the diluter's toxicant mixing vessel and all non-control test vessels (nominal concentration of the stock solution was 4.0 mg/L). Nominal concentrations of 0 (control and solvent control), 0.6, 1.0, 1.6, 2.4 and 4 mg/L and measured of: ND (<0.02 mg/L; control and solvent control), 0.18, 0.32, 0.48, 0.66, and 1.0 mg/L. Concentrations were stable during the 96 hour testing period. Mean measured concentrations were used for all calculations. Oysters used in the test were obtained from a commercial supplier and acclimated to test conditions for 10 days. Animals were in good condition at the beginning of the study. Exposure of oysters to the test substance resulted in a 96 hour median effective concentration of 0.52 mg/L test substance, with a 95 % confidence interval of 0.49 to 0.55 mg/L. The 96 hour no observed effect concentration was 0.18 mg/L.

Description of key information

All available data was assessed and the studies representing the worst-case effects are included here as key. The results can be considered worst-case and are selected for the CSA. Other studies are included as supporting information.

Freshwater 48-h EC50 = 0.6 mg/L, flow-through, Daphnia magna, mortality, EPA 72 -2; Ward 1993f

Marine water, 96-h LC50 = 0.35 mg/L, flow-through, Mysidopsis bahia, mortality, EPA 72-3, Ward 1993g

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

EC50

Effect concentration:

0.6 mg/L

Marine water invertebrates

Marine water invertebrates

Dose descriptor:

LC50

Effect concentration:

0.35 mg/L

Additional information

EPA 72 -2, Ward 1993f, Daphnia

The acute toxicity of the test substance to daphnid, Daphnia magna was tested in a study conducted according to the EPA 72-2 guideline and in compliance with GLP. The test was performed under flow-through conditions with five concentrations of test substance, a dilution water control, and a solvent control at a temperature of 20 ± 1°C. The dilution water was filtered dechlorinated tap water adjusted to a hardness of 160 to 180 mg/L. The test was performed at and above the apparent water solubility of the test substance as evidenced by the observation of white particles floating on the water surface in the diluter's toxicant mixing vessel (nominal concentration of the stock was 2.5 mg/L). Nominal concentrations of 0 mg/L (control and solvent control), 0.38, 0.62, 1.0, 1.5, and 2.5 mg/L. measured concentrations of in centrifuged test media were: (<0.02 mg/L, control and solvent control), 0.16, 0.26, 0.39, 0.60, and 0.84 mg/L and concentrations were stable during the 48 hour testing period. Mean measured concentrations were used for all calculations. Organisms used in the test were produced from in house cultures maintained and acclimated at the testing laboratory under test conditions. After 48 hours of exposure the control had an average wet weight (blotted dry) of 0.16 mg. All animals were in good condition at the beginning of the study. Exposure of daphnids to the test substance resulted in a 48 hour median lethal concentration EC50 of 0.60 mg/L, with a confidence interval of 0.51 to 0.73 mg/L. The 48-hour no observed effect concentration was 0.26 mg/L.

EPA 72 -3, Ward 1993g, Mysid

The acute toxicity of the test substance to the mysid, Mysidopsis bahia was tested in a study conducted following the EPA 72-3 guideline and in compliance with GLP. The test was performed under flow-through conditions with five concentrations of test substance, a dilution water control, and a solvent control at a temperature of 22 ± 1°C. The dilution water was filtered natural sea water adjusted to a salinity of 16 to 17 parts per thousand. The test was performed at and above the apparent water solubility of the test substance, as evidenced by the observation of white in the diluter's toxicant mixing vessel and all non-control test vessels (nominal concentration of the stock solution was 1.0 mg/L). Nominal concentrations of the test substance were: 0.15, 0.25, 0.40, 0.60, and 1.0 mg/L. Mean measured concentrations of the test substance in centrifuged test media were: 0.14, 0.22, 0.34, and 0.53 mg/L and concentrations were stable during the 96 hour testing period. Mean measured concentrations were used for all calculations. All organisms used in the test were produced by an in-house culture that was maintained at test conditions for more than 10 days at the testing facility. After 96 hours of exposure the control organisms had an average wet weight (blotted dry) of 0.76 mg. All animals were in good condition at the beginning of the study. Exposure of mysids to the test substance resulted in a 96-hour lethal concentration (LC50) of 0.35 mg/L with a 95 % confidence interval of 0.22 to 0.53 mg/L. The 96-hour no observed effect concentration was 0.22 mg/L.

Supporting study

EPA 72 -3, Ward 1993h, Oyster

The acute toxicity of the test substance to the Crassostrea virginica, as judged by the deposition of new shell, was determined in the study performed following the EPA 72-3 guidance and in compliance with GLP.  The test was performed under flow-through conditions with five concentrations of test substance, a dilution water control, and a solvent control at a temperature of 22±1°C. The dilution water was natural sea water. The test performed at and above the apparent water solubility of the test substance, as evidenced by the observation of white in the diluter's toxicant mixing vessel and all non-control test vessels (nominal concentration of the stock solution was 4.0 mg/L). Nominal concentrations of 0 (control and solvent control), 0.6, 1.0, 1.6, 2.4 and 4 mg/L and measured of: ND (<0.02 mg/L; control and solvent control), 0.18, 0.32, 0.48, 0.66, and 1.0 mg/L. Concentrations were stable during the 96 hour testing period. Mean measured concentrations were used for all calculations. Oysters used in the test were obtained from a commercial supplier and acclimated to test conditions for 10 days. Animals were in good condition at the beginning of the study. Exposure of oysters to the test substance resulted in a 96 hour median effective concentration of 0.52 mg/L test substance, with a 95 % confidence interval of 0.49 to 0.55 mg/L. The 96 hour no observed effect concentration was 0.18 mg/L.