3-anilino-5-methyl-5-(4-phenoxyphenyl)-1,3-oxazolidine-2,4-dione;famoxadone (ISO)

Bioaccumulation: aquatic / sediment

Link to relevant study record(s)

Reference

Endpoint:

bioaccumulation in aquatic species: fish

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 305 E (Bioaccumulation: Flow-through Fish Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPP 165-4 (Laboratory Studies of Pesticide Accumulation in Fish)

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

Substance ID: [14-C-POP]DPX-JE874
Lot #: 2675-268
Radiochemical purity: >97%
Specific activity: 59.63 µCi/mg

Substance ID: [14-C-PA]DPX-JE874
Lot #: 2868-107
Radiochemical purity: >97%
Specific activity: 54.89 µCi/mg

Radiolabelling:

yes

Details on sampling:

- Sampling intervals/frequency for test organisms: Total [14C]residue levels for whole fish were determined by direct radioassay on eight sampling days during the uptake phase and on six sampling days during the depuration phase. Additional fish were sampled on the last day of the uptake (exposure) and depuration phase for total [14C]residues in the fillet and remaining carcass.
- Sampling intervals/frequency for test medium samples: Water was sampled daily in each of the three exposure groups for the determination of total [14C] residues by direct radioassay. During the depuration phase, water samples were taken daily from the low dose [14C-POP] test substance group, and on Day 15, 16, 17, 21, 24, and 28 from the high dose [14C-PA] test substance group.
- Details on sampling and analysis of test organisms and test media samples: The amount of total [14C]test substance equivalent residues in the whole fish, fillet and remaining carcass was determined by direct oxygen combustion and LSC. Radioactivity in water samples was measured by direct LSC. Radioactivity in whole fish, fillet and remaining carcass was measured by combusting the samples (approximately 0.12 to 1.3 g wet weight) in a Harvey biological material oxidizer and collecting the 14CO2 in 15 mL of liquid scintillation cocktail.
HPLC was used for confirmation of the radiochemical purity of [14C-POP] and [14C-PA]test substance, and for analysis of water and fish samples. The detection of radioactive components was made by either an in-line radiochemical detector, or, in cases of low sample radioactivity, by fraction-collection and LSC.

Vehicle:

yes

Remarks:

Dimethylformamide (DMF)

Details on preparation of test solutions, spiked fish food or sediment:

PREPARATION AND APPLICATION OF TEST SOLUTION
a. [14C-POP]Test Substance Stock Solution Preparation
Eighty mg of [14C-POP] test substance were dissolved in acetone and the resulting solution was divided equally among five 500-mL Wheaton bottles. After the acetone was evaporated to dryness, the Wheaton bottles were stored in the freezer. A stock solution of [14C-POP] test substance (0.040 mg/mL nominal concentration) was prepared by dissolving the contents of a Wheaton bottle in 400 mL of DMF. A second stock solution of 0.004 mg/mL nominal concentration was prepared by ten-fold dilution of the 0.040 mg/mL stock solution.
b. [14C-PA] Test Substance Stock Solution Preparation
A stock solution of [14C-PA] test substance (0.040 mg/mL nominal concentration) was prepared by dissolving 38.08 mg of [14C-PA] test substance in 952 mL of DMF. Equal portions of the stock solution were transferred to each of two bottles.
c. Stock Solution Delivery
The [14C] test substance stock solution delivery system consisted of an infusion syringe pump calibrated to deliver a target volume of 45 mL of [14C] test substance stock solution or DMF (equivalent to a DMF concentration of 0.06 mL/L) to approximately 750 L of water on each day during the uptake phase.

Test organisms (species):

Lepomis macrochirus

Details on test organisms:

TEST ORGANISM
- Common name: Bluegill Sunfish
- Strain: Lepomis macrochirus
- Source: Northeastern Biologists in Rhinebeck, New York
- Description of housing/holding area: Fish were held in 242- to 545-L fiberglass circular tanks (49-cm water depth)
- Feeding during test
- Food type: Frozen brine shrimp
- Frequency: Once daily

ACCLIMATION
- Acclimation period: 118 to 139 days
- Type and amount of food: Live, newly-hatched brine shrimp or frozen brine shrimp
- Feeding frequency: Generally twice a day on weekdays, and once a day on weekends and holidays

Route of exposure:

aqueous

Justification for method:

aqueous exposure method used for following reason: A steady-state approach with two-compartment model (water and fish) was used to determine the BCF

Test type:

flow-through

Water / sediment media type:

other: Dilution water from well

Total exposure / uptake duration:

>= 14 - <= 28 d

Total depuration duration:

14 d

Test temperature:

20.7-23.0°C

pH:

6.5-7.7

Dissolved oxygen:

6.0-8.6 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: Test chambers were 54-L stainless steel aquaria equipped with an overflow drain that maintained a water volume of 45-L (25-cm liquid depth).
- Renewal rate of test solution (frequency/flow rate): The [14C] test substance stock solution delivery system consisted of an infusion syringe pump calibrated to deliver a target volume of 45 mL of [14C] test substance stock solution or DMF (equivalent to a DMF concentration of 0.06 mL/L) to approximately 750 L of water on each day during the uptake phase.
- No. of organisms per vessel: 100
- Biomass loading rate: 0.09 and 0.11 g/L/day for [14C-POP]test substance and [14C-PA]test substance, respectively.

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Dilution water used for the studies originated from the Test Facility well, a 360-foot well cased and sealed to bedrock to prevent contamination from surface run-off. The water was aerated, filtered through 50-цш and 10-ц.ш filters to remove particulates, and then distributed to the exposure system through aged PVC pipes.
- Chlorine: 7 mg/L

OTHER TEST CONDITIONS
- Adjustment of pH: Yes, by using an infusion syringe pump to deliver 45 mL of 21.3% phosphoric acid (1:3 v/v 85% phosphoric acid/water) to approximately 750 L of water per day for the duration of the exposure phase. The pH of the water was not adjusted during the depuration phase.
- Photoperiod and light: A 16-hour light (62 - 82 Lux) and an 8-hour dark photoperiod with 25 minutes of transitional lighting (1 Lux) was used throughout the study.
RANGE-FINDING / PRELIMINARY STUDY
- Exposure concentrations for the bioconcentration study were selected on the basis of the results of a flow-through, acute toxicity study using bluegill sunfish. The 96-hour median lethal concentration (LC50) for the test substance was 13 µg/L, and the 96-hour no observable effect concentration (NOEC) was 9.3 µg/L, based on the following toxicity observations: dark coloration, gasping for air and lying on bottom of test chamber. The exposure concentrations, 0.240 and 2.40 µg/L, for the bioconcentration study represent approximately 1/50 and 1/5 of the 96-hour LC50 value, and are approximately equal to 7 and 70 times the detection limit of the test substance in the water.

Nominal and measured concentrations:

[14C-POP]test substance: 0.240 µg/L and 2.40 µg/L (nominal)
[14C-PA]test substance: 2.40 µg/L (nominal)

Details on estimation of bioconcentration:

A steady-state approach was used to determine the BCF, the uptake rate constant (k1), and the depuration rate constant (K2). This is a two-compartment model (water and fish) used to describe the movement of the test substance into and out of the test fish.
The observed BCF was determined as the ratio of [14C]residue concentration in fish tissue (Cf) and the mean concentration of radioactivity in water (Cw) during the uptake phase. The observed BCF at steady state was calculated from the average of individual whole fish [14C]residue concentrations at plateau and the mean concentration of radioactivity in water. BCFs for fillet and remaining carcass were also calculated at the end of the uptake phase. Steady state was defined as three consecutive sampling days for which Cf values showed no statistically significant differences (p≤0.05).

Key result

Conc. / dose:

2.4 µg/L

Temp.:

>= 20.7 - <= 23 °C

pH:

6.5

Type:

BCF

Value:

3 400 dimensionless

Basis:

other: whole fish

Calculation basis:

steady state

Remarks on result:

other: [14C-PA]test substance

Key result

Conc. / dose:

0.24 µg/L

Temp.:

>= 20.7 - <= 23 °C

pH:

6.5

Type:

BCF

Value:

2 800 dimensionless

Basis:

other: whole fish

Calculation basis:

steady state

Remarks on result:

other: [14C-POP]test substance

Rate constant:

overall uptake rate constant (L kg-1 d-1)

Value:

970

Remarks on result:

other: [14C-POP]test substance

Rate constant:

overall uptake rate constant (L kg-1 d-1)

Value:

1 056

Remarks on result:

other: [14C-PA]test substance

Rate constant:

overall depuration rate constant (d-1)

Value:

0.373

Remarks on result:

other: [14C-POP]test substance

Rate constant:

overall depuration rate constant (d-1)

Value:

0.314

Remarks on result:

other: [14C-PA]test substance

Details on kinetic parameters:

- Uptake rate constant (k1): 970±23 and 1056±7.2 for 0.240 µ/L [14C-POP] and 2.40 µg/L [14С-РА], respectively
- Depuration rate constant (k2): 0.373±0.007 and 0.314±0.002 for 0.240 µ/L [14C-POP] and 2.40 µg/L [14С-РА], respectively

Details on results:

- Mortality of test organisms: No adverse effects were noted among the control or test fish due to exposure to either 0.240 µg/L [14C-POP]test substance or 2.40 µg/L [14C-PA] test substance. No mortality was seen in the control chamber from Day 10 to 42 of the [14C-POP] test substance group. Six percent of the fish were either dead or unaccounted for in the low dose chamber at the end of 42 days. No mortality was observed in the control or exposure chambers of the 2.40 µg/L [14C-PA] test substance group.
- Other: On Day 9 of the uptake phase in the [14C-POP] test substance group, fish in the 2.40 µg/L and control chambers were accidentally exposed to bleach during cleaning. The exposure phase of the high dose [14C-POP] test substance group was discontinued, and the DMF control chamber was restocked on Day 10 with an additional 80 unexposed fish. Since the uptake of [14C-POP] test substance had reached steady state, a repeat of the high dose exposure with this radiolabel was not warranted.

Reported statistics:

The statistical method used to analyze the data was analysis of variance (ANOVA). Time to steady state was determined by analyzing uptake data from fish exposed to the test substance
The uptake rate constant (K1) and depuration rate constant (K2) were determined by using SimuSolv, a non-linear kinetic modeling software program that provides optimal parameter estimates for K1 and k2 by using actual bioconcentration study data.

Conclusions:

The steady-state bioconcentration factor (BCF) for [14C] test substance in whole fish ranged from 2400 to 3400 with an average of approximately 2800.

Executive summary:

The bioconcentration potential of the test substance was evaluated by exposing juvenile bluegill sunfish (Lepomis macrochirus) under flow-through conditions to [14C] test substance. Exposures were conducted with 0.240 µg/L and 2.40 µg/L nominal [14C-POP] test substance, and 2.40 µg/L nominal, [14C-PA] test substance. Exposure to 0.240 µg/L [14C-POP] test substance was carried out for 28 days followed by 14 days of depuration, and exposure to 2.40 µg/L [14C-PA] test substance was carried out for 14 days followed by 14 days of depuration. Exposure to 2.40 µg/L [14C-POP] test substance was terminated after nine days. The study controls consisted of fish exposed under flow-through conditions to water containing 0.06 mL/L of dimethylformamide (DMF).

Water was sampled daily in each of the three exposure groups for the determination of total [14C] residues by direct radioassay. During the depuration phase, water samples were taken daily from the low dose [14C-POP] test substance group, and on Day 15, 16, 17, 21, 24, and 28 from the high dose [14C-PA] test substance group. Total [14C]residue levels for whole fish were determined by direct radioassay on eight sampling days during the uptake phase and on six sampling days during the depuration phase. Additional fish were sampled on the last day of the uptake (exposure) and depuration phase for total [14C]residues in the fillet and remaining carcass. Characterization of [14C]residues in fillet and carcass extracts was based on fish sampled on the last day of the uptake phase. Water samples were also taken during the uptake phase for [14C]residue characterization.

Average concentrations of total radioactivity (expressed in µg/L [14C] test substance equivalents), as determined by direct radioassay, measured between 85 and 102% of nominal concentrations during the uptake phase. Average concentrations of parent test substance, as determined by HPLC, ranged from 82 to 94% of nominal concentrations during the uptake phase. Total [14C]residue concentrations were used in the calculation of bioconcentration factors.

Under the conditions of exposure, the uptake of radioactivity was rapid. Whole fish [14C]residue concentrations reached steady state after 7 to 9 days. The majority (approximately 75%) of the [14C]residues were localized in the carcass at the end of the uptake phase. The steady-state bioconcentration factor (BCF) for [14C] test substance in whole fish ranged from 2400 to 3400 with an average of approximately 2800. Depuration of radioactivity was rapid following transfer of the exposed fish to clean, flowing water. Greater than 96% of the [14C]residues in whole fish, fillet and remaining carcass were eliminated at the end of the 14-day depuration period. Parent [14C] test substance was the primary radioactive component recovered from the fish tissues at the end of the uptake phase.

Description of key information

Study Type	Study Details	Value	Guideline	Reliability
Bioaccumulation: aquatic / sediment	Flow through test time in Juvenile bluegill sunfish	BCF in whole fish ranged from 2400 to 3400 with an average of approximately 2800	OECD 305E; EPA 165-4	1

Key value for chemical safety assessment

BCF (aquatic species):

2 800 L/kg ww