2-chloro-N-[[[4-(trifluoromethoxy)phenyl]amino]carbonyl]benzamide

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

Study period:

15-May-1990 to 15-Nov-1990

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

The study was conducted to GLP

Qualifier:

according to guideline

Guideline:

other: U.S. EPA Pesticide Assessment Guideline Subdivision E

Version / remarks:

1982

Qualifier:

according to guideline

Guideline:

EPA OPP 72-6 (Aquatic Organism Accumulation Tests)

Version / remarks:

1982

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

1982

GLP compliance:

yes (incl. QA statement)

Radiolabelling:

yes

Details on sampling:

Fish
Four fish from each chamber were collected and processed individually. The fish were dissected into edible (body, muscle, skin, skeleton) and viscera / nonedible (head, internal organs, fins). The samples were treated and measured.

Water
On each sampling day, 3 samples of 7 mL of water were removed from each aquarium using 10 mL pipettes. The concentrations of 14C calculated as [14C]-Triflumuron in water were calculated by liquid scintillation counting of triplicate 7-ml samples pipetted directly from each control and test tank. To each sample 7 mL scintillation cocktail (United Technologies Packard Instant Scint. Gel) were added.

Vehicle:

no

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

The stock solutions for the treatment of the fish were prepared as follows:
The radioactive material (ca. 13.73 MBq, 2.3 MBq/mg, 6.16 mg delivered in 20 mL Acetonitrile) was combined with 43.8 mg "cold" test substance and diluted in 2 1 acetone p.a. by adding the solvent. Thus the concentration in the stock solution was 25 mg/L with a specific radioactivity of 275 kBq/mg or 16500 dpm/µg (equivalent to 289 dpm per 7 mL sample). At the same time, a stock solution of "cold" Triflumuron in acetone was prepared (25 mg/L) and kept under similar conditions for stability analysis

The nominal concentration used in this study was 2.5 µg/L. It was less than 1% of the acute LC50 for Bluegill Sunfish (9 mg/L) but higher concentrations could not be tested due to the very low water solubility of Triflumuron.
A dosing system comprising a Hamilton RMicrolab MT dispenser with a 250 µL-syringe for each aquarium controlled by an EPSON HX20 computer (for dosing of stock solution), and flow-meters (for water flow control) was used for the introduction of [14C]-Triflumuron and diluent water into the 100 liter test aquaria. Aerated reconstituted water was delivered to the glass aquaria at an average rate of approximately 25 L/hour/aquarium during the exposure period (28 days), an amount sufficient to replace the approximately 100 liter test volume about 6 times in a 24 hour period and stock solution ([14C]-Triflumuron in acetone) was dosed at a rate of 50 µL every 72 seconds ( = 2.5 mL/h).
Water (continuously 25 L/h) and aliquots of [14C]-Triflumuron stock solution (25 mg/L, 0.05 mL every 72 sec) were delivered to a 2000 mL-mixing cell to yield a nominal exposure concentration of 2.5 µg/L. The mixture was running continuously from the mixing vessel into the respective aquarium.
The control aquaria also received an amount of acetone solvent (0.1 mL/L) as the exposure aquaria.
The exposure system consisted of one 2.5 µg/L nominal concentration aquarium and one control aquarium. The aquaria were labelled with the study number and treatment level.
The test aquaria arranged in a lab room were kept at 22°C (± 1) by adding diluent water electronically thermostated to that temperature. Temperature was measured once daily on working days and the range of temperature deviations was followed by a mercury-minimum-maximum-thermometer, which was reset after each reading.
The diluter system was calibrated by volumetric measurements of syringe dispenser aliquots and flow-rate of flow meters.

Test organisms (species):

Lepomis macrochirus

Details on test organisms:

The bluegill sunfish (Lepomis macrochirus) were used in the bioconcentration study. The fish were identified to species by the supplier. Confirmation of species identification was performed when necessary using the taxonomic keys. All test fish were held in culture tanks on a 16-hour daylight photoperiod and observed for at least 14 days prior to testing. No mortality was noted 14 days prior to the test initiation and all unsuitable fish (i.e., injured, deformed, etc.) were eliminated from inclusion in the test prior to assignment to test groups. A continuous record of fish observations during the holding period, along with any prophylactic and therapeutic disease treatments, is included in the raw data.

Length 5.28 ± 0.4 cm (mean ± SD), bodyweight 2.09 ± 0.6 g.

Route of exposure:

aqueous

Test type:

flow-through

Water / sediment media type:

natural water: freshwater

Remarks:

Distilled water

Total exposure / uptake duration:

28 d

Total depuration duration:

14 d

Hardness:

48 mg CaCO3/L

Test temperature:

21-23 °C (22.0 ± 0.5)

pH:

6.9 - 7.7. (7.5 ± 0.2)

Dissolved oxygen:

8.1 - 9.2 mg/L

TOC:

<2 mg/L

Details on test conditions:

Samples were taken at least at times as described in "Hazard Assessment Guidelines, Subdivision E, Hazard Evaluation Wildlife and Aquatic Organisms, §72-6, 1982" to determine the time course of accumulation and the time to reach steady state.

Uptake phase
The uptake phase was initiated by transferring groups of 56 randomly selected and previously acclimated fish (length 5.28 ± 0.4 cm (mean ± SD), body weight 2.09 ± 0.6 g) to each of the control and test chambers. The initial loading was 1.2 g fish/L and 0.20 g fish/L/day. The fish were observed initially and every 24 hours on working days thereafter during the exposure period of 28 days for mortality and/or adverse behaviour. At the same intervals pH and dissolved oxygen were measured in all aquaria. The temperature was recorded hourly in the control tank. Water and fish were sampled throughout the uptake period.

Depuration Phase
On day 28 of theexposure period, the addition of the [14C]-Triflumuron test material ceased. At the beginning of the depuration phase, the aquaria were cleaned mechanically, emptied by suction to a water height of ca. 5 cm, and filled with uncontaminated diluent water (22°C). During that procedure the fish remained in the aquaria. The fish were then exposed to flowing uncontaminated diluent water (22°C) for 14 days. During the depuration period, water and fish were sampled and radioassayed. The fish were observed initially and every 24 hours on working days during the depuration period of 14 days for mortality and/or adverse behaviour. At the same intervals pH and dissolved oxygen were measured in all aquaria. The temperature was recorded hourly in the control tank.

Nominal and measured concentrations:

The nominal concentration used in this study was 2.5 µg/L. It was less than 1% of the acute LC50 for Bluegill Sunfish (9 mg/L) but higher concentrations could not be tested due to the very low water solubility of Triflumuron.
The average water concentration (using the mean value for each sample) during the uptake phase was 2.10(± 0.30) mg/L. These concentrations compared very well with the expected nominal concentration of 2.5 µg/L for [14C]-Triflumuron.

Details on estimation of bioconcentration:

BASIS INFORMATION
The log octanol/water partition coefficient (log pow) is 4.91.

BIOCONCENTRATION FACTOR
Bioconcentration factors (BCFs) were calculated for total [14C]-residues. BCFs for whole fish were calculated from BCFs of edible and non-edible portions. The kinetic data were calculated using a computer program (BIOFAC, 2) which models a two compartment system.

Key result

Conc. / dose:

2.1 µg/L

Temp.:

22 °C

Type:

BCF

Value:

612 dimensionless

Basis:

whole body d.w.

Key result

Conc. / dose:

2.1 µg/L

Temp.:

22 °C

Type:

BCF

Value:

296 dimensionless

Basis:

edible fraction

Key result

Conc. / dose:

2.1 µg/L

Temp.:

22 °C

Type:

BCF

Value:

1 033 dimensionless

Basis:

non-edible fraction

Key result

Elimination:

yes

Parameter:

DT50

Depuration time (DT):

1.36 d

Remarks on result:

other: whole fish

Key result

Elimination:

yes

Parameter:

DT50

Depuration time (DT):

0.73 d

Remarks on result:

other: edible part

Key result

Elimination:

yes

Parameter:

DT50

Depuration time (DT):

0.96 d

Remarks on result:

other: Viscera

Details on kinetic parameters:

- Uptake rate constant k(1)(L/day):
Whole fish: 312 (±22)
Edible: 282 (±46)
Viscera: 743 (±37)

- Depuration rate constant k(2) (L/day)
Whole fish: 0.51 (±0.03)
Edible: 0.95 (±0.15)
Viscera: 0.72 (±0.03)
:
The BIOFAC calculated BCF values corresponded well with the average steady-state bioconcentration factors of 288, 1031, and 622 X for total [14C]-radioactivity (Triflumuron plus metabolites) in edible tissue, nonedible tissue and whole fish, respectively on days 7 to 28.

Details on results:

Water concentrations ranged from 1.76 µg/L to 2.80 µg/L through 28 days of the bioconcentration (uptake) phase. The average water concentration (using the mean value for each sample) during the uptake phase was 2.10(± 0.30) mg/L. These concentrations compared very well with the expected nominal concentration of 2.5 µg/L for [14C]-Triflumuron.
The specific radioactivity of [14C]-Triflumuron was 16500 dpm/µg.

In terms of parent compound equivalents, the absolute mean tissue residue concentration in fresh biological matrix at steady state was calculated to be 624 µg/kg for edible tissue, 2175 µg/kg for viscera, and 1288 µg/kg for whole fish. These values corresponded steady state (days 7 to 28) bioconcentration factors of 288, 1031 and 622 X, respectively.

An analysis of depuration rates by day 3 of the elimination period showed 93, 87 and 89 percent depuration in edible tissue, nonedible tissue and whole fish, respectively. The depuration data indicated a very rapid decrease in tissue concentration.

Reported statistics:

The uptake rate constant (K1), depuration rate constant (K2), time to onehalf clearance, and steady-state bioconcentration factor (BCF) for whole fish were determined using the BIOFAC non-linear kinetic modeling computer programme for the bioconcentration study with [14C]-Triflumuron.

Conclusions:

This study was performed to investigate the bioconcentration of triflumuron in bluegill sunfish exposed for 28-days under flow-through conditions at a concentration of 2.10 µg/L. Triflumuron is accumulated very rapidly by bluegill sunfish with a total residue bioconcentration factor of 612 X for whole fish. When exposure ceases, the residues are depurated quickly with a half-life of about 33 hours. Accumulation in edible parts is much less (296 X) than in whole fish (612 X). The bioconcentration factor for Triflumuron may be overestimated in this study
because all calculations refer to radioactivity. Thus the BCFs given in this report refer to total residues form exposure to a constant concentration of Triflumuron.

Description of key information

This study was performed to investigate the bioconcentration of triflumuron in bluegill sunfish exposed for 28-days under flow-through conditions at a concentration of 2.10 µg/L. Triflumuron is accumulated very rapidly by bluegill sunfish with a total residue bioconcentration factor of 612 X for whole fish. When exposure ceases, the residues are depurated quickly with a half-life of about 33 hours. Accumulation in edible parts is much less (296 X) than in whole fish (612 X). The bioconcentration factor for Triflumuron may be overestimated in this study because all calculations refer to radioactivity. Thus, the BCFs given in this report refer to total residues form exposure to a constant concentration of Triflumuron.

Key value for chemical safety assessment

BCF (aquatic species):

612 dimensionless