Dichlobenil

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:

29 September 1986 to 02 June 1987; January 1987 to 04 January 1988

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPP 72-6 (Aquatic Organism Accumulation Tests)

Deviations:

no

GLP compliance:

yes

Radiolabelling:

yes

Details on sampling:

Water and fish were sampled throughout the uptake period on days 0.17, 1, 3, 7, 14, 21 and 28 and were radio-assayed.

Vehicle:

yes

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

PREPARATION AND APPLICATION OF TEST SOLUTION
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): dimethylformamide

Test organisms (species):

Lepomis macrochirus

Details on test organisms:

TEST ORGANISM
- Common name: Bluegill sunfish
- Source: Osage Catfisheries Inc, Osage Beach, Missouri, USA
- Length at study initiation: 50 ± 4.6 mm
- Weight at study initiation: 40 ± 1.2 g
- Feeding during test: Yes
- Food type: standard commercial fish food
- Frequency: daily

ACCLIMATION
- Acclimation period: 14 days

Route of exposure:

aqueous

Test type:

flow-through

Water / sediment media type:

natural water: freshwater

Total exposure / uptake duration:

28 d

Total depuration duration:

14 d

Details on test conditions:

TEST SYSTEM
- Test vessel: 100 L aquaria
- Material, size, headspace, fill volume: fill volume - 70 L
- Aeration: yes
- Type of flow-through: proportional diluter
- Renewal rate of test solution (frequency/flow rate): 7.1 times per 24 hour period
- No. of organisms per vessel: 120
- No. of vessels per concentration (replicates): 1
- No. of vessels per control / vehicle control (replicates): 1

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: well water

Nominal and measured concentrations:

0.15 mg/L (nominal)

Reference substance (positive control):

no

Details on estimation of bioconcentration:

BASIS FOR CALCULATION OF BCF
- Estimation software: BIOFAC computer program

Key result

Type:

BCF

Value:

56 other: ppm fish/ppm water

Basis:

whole body w.w.

Time of plateau:

1 d

Calculation basis:

steady state

Key result

Elimination:

yes

Parameter:

DT50

Depuration time (DT):

0.3 d

Details on kinetic parameters:

A non-linear two-compartment kinetics modelling computer program (BIOFAC) was used for analysis of the uptake/depuration whole fish data. This method estimated an uptake rate constant (K1) of 130 (± 16) ppm fish/ppm water/day, clearance rate constant (K2) of 2.3 (± 0.28) days, time for 50 % clearance of 0.30 (± 0.04) days, bioconcentration factor (BCF) of 56 (± 9.7) ppm fish/ppm water and time to reach 90 % of steady-state of 1.0 (± 0.12) days.

The BIOFAC calculated BCF value was 98 % of the average observed whole fish bioconcentration factor (57) for [14C]-dichlobenil fish residues for days 3, 7, 14, 21, and 28.

Metabolites:

The two water samples analysed showed only one [14C]-Iabelled compound in the chromatogram with the same retention time as the test material.

Four bluegill sunfish extracts were analysed. Because of the complex biological matrices of the fish samples UV-detection gave no definite identification. The radioactivity detector, however, showed only one unequivocal peak, which had the same retention as dichlobenil for all four samples.

In this way it was demonstrated that fish extracts and aquarium water contained only one major radioactive component. This component was identified by GC-MS as the test material. In the fish extracts and aquarium water no other radioactivity components were found that represented more than 1 % of the radioactivity content.

Details on results:

Daily bioconcentration factors ranged from 18 to 32x, 33 to 63x, and 48 to 110x for fillet, whole fish and viscera, respectively.

Uptake tissue concentrations of [14C]-dichlobenil ranged from 2.3 to 4.4 ppm for fillet, 4.3 to 8.8 ppm for whole fish, and 6.3 to 14 ppm for viscera.

Radioanalysis throughout the depuration period indicated >96, >97, and 97 % depuration from fillet, whole fish and viscera, respectively.

The fillet concentration of [14C]-dichlobenil dropped from a day 28 uptake value of 3.9 ppm to less than minimum quantifiable limits (MQL) by day 14 of the depuration period.

Whole fish levels decreased from 6.5 ppm on day 28 uptake to less than MQL by the end of the study; whereas, viscera concentration dropped from 9.3 ppm on day 28 uptake to 0.29 ppm by day 14 depuration.

Validity criteria fulfilled:

not specified

Conclusions:

Under the conditions of the test, the following were estimated using a non-linear two-compartment kinetics modelling computer program: an uptake rate constant (K1) of 130 (± 16) ppm fish/ppm water/day, clearance rate constant (K2) of 2.3 (± 0.28) days, time for 50 % clearance of 0.30 (± 0.04) days, bioconcentration factor (BCF) of 56 (± 9.7) ppm fish/ppm water and time to reach 90 % of steady-state of 1.0 (± 0.12) days. The [14C]-residue in the two water samples as well as in the two edible tissue samples and the two viscera samples consisted only of [14C]-dichlobenil.

Executive summary:

In a GLP compliant bioaccumulation study conducted in line with standardised guidelines EPA OPP 165 -4 and EPA OPP 72 -6, the bioaccumulation of the test material was determined. Bluegill sunfish was exposed to the test material for 28 days at a nominal test material concentration of 0.15 mg/L with a depuration phase of 14 days. Residues were subsequently identified in water, viscera and fillet samples.

Under the conditions of the test, a Bioconcentration factor of 56 ppm fish/ppm water was determined. In addition, an uptake rate constant (K1) of 130 (± 16) ppm fish/ppm water/day, clearance rate constant (K2) of 2.3 (± 0.28) days, time for 50 % clearance of 0.30 (± 0.04) days and time to reach 90 % of steady-state of 1.0 (± 0.12) days were calculated using non-linear two-compartment kinetics modelling computer program. The [¹⁴C]-residue in the two water samples as well as in the two edible tissue samples and the two viscera samples consisted only of [¹⁴C]-dichlobenil.

Description of key information

The BCF of the test material was determined to be 56 ppm fish/ppm water according to a study performed in line with EPA Guidelines 72-6 and 165.4.

Additional information

In a GLP compliant bioaccumulation study conducted in line with standardised guidelines EPA OPP 165 and EPA OPP 72-6, the bioaccumulation of the test material was determined. Bluegill sunfish was exposed to the test substance for 28 days at a nominal test material concentration of 0.15 mg/L with a depuration phase of 14 days. Residues were subsequently identified in water, viscera and fillet samples. Under the conditions of the test, a Bioconcentration factor of 56 ppm fish/ppm water was determined. In addition, an uptake rate constant (K1) of 130 (± 16) ppm fish/ppm water/day, clearance rate constant (K2) of 2.3 (± 0.28) days, time for 50 % clearance of 0.30 (± 0.04) days and time to reach 90 % of steady-state of 1.0 (± 0.12) days were calculated using non-linear two-compartment kinetics modelling computer program. The [¹⁴C]-residue in the two water samples as well as in the two edible tissue samples and the two viscera samples consisted only of [¹⁴C]-dichlobenil