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

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:

10 Oct 2000 to 09 April 2001

Reliability:

1 (reliable without restriction)

Qualifier:

according to guideline

Guideline:

OECD Guideline 305 (Bioaccumulation in Fish: Aqueous and Dietary Exposure) -I: Aqueous Exposure Bioconcentration Fish Test

Version / remarks:

June 1996

Deviations:

yes

Remarks:

See deviations to guidelines in 'Any other information on materials and methods incl. tables'

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

October 18, 1982

Deviations:

yes

Remarks:

See deviations to guidelines in 'Any other information on materials and methods incl. tables'

GLP compliance:

yes (incl. QA statement)

Radiolabelling:

yes

Details on sampling:

- Water: O2 and temperature were measured at least 3 times, pH and conductivity once a week, directly in the aquaria. Water specimens of 10 mL from each test aquarium and the control were taken for analysis of total radioactivity in water at days -4, -1, 0, 1, 2, 3, 7, 9, 13,14,17,21, 24 and 28 of the exposure phase and at days 1, 2, 3, 7, 10 and 14 of the depuration phase.
For the identification of the test item, specimens of up to 500 mL were taken at days -4, -1, 0, 1, 3, 7, 14, 17, 21, 24 and 28 of the exposure phase, and at day 1 and 14 of the depuration phase. Specimens from the control tank were taken at day 0 and 28 of the exposure phase and at day 14 of the depuration phase. Aliquots of 250 mL of the specimens at these days were passed through a extraction column, which had been preconditioned with about 5 mL of acetonitrile and about 5 mL of bidistilled water. Specimens were eluted with at least 2 mL of acetonitrile and made up to a specified volume with bidistilled water.
- Fish: For analysis of radioactivity in edible and non-edible portions of fish specimens, 4 fish were taken from each test tank at days 0, 1, 3, 7, I4, 17, 21, 24 and 28 of the exposure phase and at days 1, 3, 7, 10 and 14 of the depuration phase and placed into a tricaine solution for euthanasia. At day 0 and 28 of the exposure phase and at day 14 the depuration phase, 4 fish of the control tank were taken for background radioactivity measurements. Thereafter, the fish were dissected into edible (body muscle, skin and skeleton) and non-edible head and organs). The corresponding portions were pooled, placed into glass vials and exactly 43 g of tissue solubilizer were added. After the complete digesting of the tissues, aliquots of the solutions were submitted to LSC.
For the analysis of the amount of parent, metabolites and lipid content in fish, a total amount of 32 fish (2 portions of 16 fish each) were taken from each test tank at day 28 of exposure. For the analysis of the lipid content and determination of the storage stability, I6 additional fish specimens were taken from the control tank at day 0 of the study. For the determination of the lipid content at the end of the study, 8 additional fish were taken from the control tank at day 42.
- Storage of specimens: Specimens not directly needed for analysis were stored at -18°C in the dark. If specimens were stored before analysis, stability data were collected to show that the subsequent analysis are valid. At the completion of the study all biological and analytical specimens were destroyed, as their storage stability cannot be guaranteed for longer time periods.

Vehicle:

yes

Remarks:

acetonitril

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

For the preparation of the stock solution 1, about 390 mg of 14C labelled test substance were dissolved in accurately 20 mL of acetonitril (= SLl). Thereafter, the amount of radioactive material present was determined by Liquid Scintillation Counting (LSC) to be 793 MBq (= 387 mg) by using the specific radioactivity of 2.05 MBq/mg of the batch. For the preparation of the stock solution 2, about 1540 mg of the unlabelled test substance were dissolved in accurately 25 mL of acetonitril. Thereafter, the amount of the unlabelled test substance present was determined by HPLC-analysis to be 1605 mg. For the preparation of the stock solution 3. Stock solution 1 was mixed with stock solution 2 and made up with acetonitril to exactly 50 ml. The amount of labelled and unlabelled test item was determined by HPLC to be 1887 mg. The amount of radioactive material was determined by LSC to be 783 MBq resulting in a specific activity of 0.415 MBq/mg test item in stock solution 3. Amounts of 795 µL SL3 for the higher and 79.5µL SL3 for lower concentration, respectively, were needed for the preparation of 1 L of application solution (deion. Water/DMF : 4/1). 1056 mL of application solution were needed for 24 h. Application solutions were prepared for 2 - 10 days at a time and used up until next renewal. The concentration of active ingredient in these application solutions was determined by LSC.

Test organisms (species):

Lepomis macrochirus

Details on test organisms:

TEST ORGANISM
- Common name: Bluegill sunfish
- Age: Juvenile
- Length at study initiation: Fish length, measured at the beginning of the study, was on average 5.3 ± 0.2 cm and the smallest and largest fish were 4.9 and 5.9 cm, respectively (for 30 fish).
- Weight: The average weight of the used fish (day -11) was 1.9 ± 0.2 grams for 300 fish.
- Handling: All transfers of fish were performed taking care to minimize possible stress due to the handling. No fish were damaged or dropped during transfer.
- Feeding: The fish were fed commercially prepared discus fish food on working days prior to and during the bioconcentration study. The feeding rate was 2% of the total biomass daily. The fish were not fed 24 hours prior to each sampling.

ACCLIMATION
- Origin and Acclimation: The fish were obtained from a commercial fish hatchery and gradually acclimated to the test conditions. They were held for at least 14 days prior to testing in water of similar quality as used in the study at the required test temperature.
- Mortality: Less than 5% mortality was observed during the acclimatization period and 3 fish died during the course of exposure.

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

Hardness:

9.7 mg/L as CaCO3

Test temperature:

22.1 °C

pH:

8.1

Dissolved oxygen:

94% saturation

TOC:

32.9 mgC/L

Conductivity:

407 μS/cm

Details on test conditions:

TEST SYSTEM
- Test vessel: Three 153 L clear glass aquaria were used as test chambers.
- Material, size, headspace, fill volume: The water depth was maintained at 40 cm. The water volume in tank was 128 L.
- Diluter: A continuous flow chemical delivery system was used. The flow of the system was adjusted to 1056 L per day and aquarium during exposure (44 L per hour, corresponding to about 8.25 aquarium volumes per day). One aquarium served as and control and received water with 0.1 mL DMF (dimethylformamide) per L dilution water, the other two aquaria continuously received the test item from the application solution (also containing DMF). Dosing pumps were used to deliver the appropriate amount of the application solutions into a mixing flask where it was diluted with water to produce the test solution. During the depuration phase, only dilution water (without DMF) was used for all three aquaria. The flow of the system was the same as during the exposure phase.
- No. of organisms per vessel: 100
- No. of vessels per concentration: 1
- No. of vessels per control: 1
- Biomass loading: The fish biomass to water ratio did not exceed 0.2 gram per litre passing through the test system during 24 hours.

TEST MEDIUM / WATER PARAMETERS
- Water parameters: The water was specified for physical parameters as total hardness, total alkalinity and conductivity before the start of the experiment.
- Dilute water pH: 7.5 - 7.6
- Dilute water dissolved oxygen: 7.5 - 7.6 mg O2/L
- Dilute water TOC: 0.4 mg/L
- Dilute water conductivity: 480 - 490 μS/cm


OTHER TEST CONDITIONS
- Photoperiod: 16 hours light and 8 hours darkness with 30 mins transition period
- Light intensity: Fluorescent light

Nominal and measured concentrations:

- Nominal concentrations: 0.0015 and 0.015 mg/L

Reference substance (positive control):

no

Lipid content:

1.53 %

Time point:

start of exposure

Remarks on result:

other: edible part

Lipid content:

3.98 %

Time point:

start of exposure

Remarks on result:

other: non-edible part

Lipid content:

2.8 %

Time point:

start of exposure

Remarks on result:

other: whole fish

Lipid content:

3.26 %

Time point:

end of exposure

Remarks on result:

other: whole fish, 0.015 mg/L

Lipid content:

3.42 %

Time point:

end of exposure

Remarks on result:

other: whole fish, 0.0015 mg/L

Lipid content:

2.2 %

Time point:

end of exposure

Remarks on result:

other: edible part, 0.0015 mgL

Lipid content:

1.9 %

Time point:

end of exposure

Remarks on result:

other: edible part, 0.015 mg/L

Lipid content:

4.6 %

Time point:

end of exposure

Remarks on result:

other: non-edible part, 0.0015 mgL

Lipid content:

4.4 %

Time point:

end of exposure

Remarks on result:

other: non-edible part, 0.015 mg/L

Key result

Conc. / dose:

0.015 mg/L

Temp.:

22 °C

pH:

8.1

Type:

BCF

Value:

185 L/kg

Basis:

whole body w.w.

Time of plateau:

28 d

Calculation basis:

kinetic

Remarks on result:

other: 5% lipid normalized, calculated outside of the study

Key result

Conc. / dose:

0.002 mg/L

Temp.:

22 °C

pH:

8.1

Type:

BCF

Value:

193 L/kg

Basis:

whole body w.w.

Time of plateau:

28 d

Calculation basis:

kinetic

Remarks on result:

other: 5% lipid normalized, calculated outside of the study

Conc. / dose:

0.015 mg/L

Temp.:

22 °C

pH:

8.1

Type:

BCF

Value:

112 L/kg

Basis:

whole body w.w.

Time of plateau:

28 d

Calculation basis:

kinetic

Remarks on result:

other: originally reported in the study

Conc. / dose:

0.002 mg/L

Temp.:

22 °C

pH:

8.1

Type:

BCF

Value:

120 L/kg

Basis:

whole body w.w.

Time of plateau:

28 d

Calculation basis:

kinetic

Remarks on result:

other: originally reported in the study

Elimination:

yes

Parameter:

DT90

Depuration time (DT):

2 d

Remarks on result:

other: whole fish, 0.015 mg/L

Elimination:

yes

Parameter:

DT90

Depuration time (DT):

3.7 d

Remarks on result:

other: whole fish, 0.0015 mg/L

Elimination:

yes

Parameter:

DT90

Depuration time (DT):

1.8 d

Remarks on result:

other: non-edible and edible tissues, 0.015 mg/L

Elimination:

yes

Parameter:

DT90

Depuration time (DT):

4 d

Remarks on result:

other: non-edible tissues, 0.0015 mg/L

Elimination:

yes

Parameter:

DT90

Depuration time (DT):

1.3 d

Remarks on result:

other: edible tissues, 0.0015 mg/L

Remarks on result:

not determinable

Metabolites:

- Metabolism Phase: Edible and non-edible fish specimens of both exposure concentrations (C1 and C2) from day 28 of the accumulation phase were analysed to determine the amount and nature of metabolites. The extractability of radioactivity with organic and aqueous solvents at ambient temperature of the fish parts was high, 97% and 96% of the edible parts of higher and lower exposure concentration, respectively, and 93% of the non-edible parts. The extractability was therefore independent of the exposure concentration. Analysis of the extracts showed that the metabolite pattern was qualitatively and almost quantitatively independent of the exposure concentration of the test substance in the fish tank and that it was qualitatively comparable in the edible and non-edible fish parts. In total, 8 metabolites were isolated by chromatographic techniques such as solid phase extraction, HPLC und TLC and were identified by H-NMR, MS techniques and/or by chromatographic comparison with reference substances.
No unidentified metabolite fraction exceeded 2.7% of the total residues in edible and non-edible fish parts. Microwave assisted treatment of the non-extractable residues of fish exposed to higher concentration (C1) additionally released 1.4% and 5.7% of the radioactivity from the edible and non-edible fish parts, respectively. From the lower exposure concentration (C2), microwave assisted treatment additionally released 5.5% of the radioactivity from the non-edible fish parts. Analysis of these extracts revealed a qualitatively similar metabolite pattern compared to the extracts obtained at ambient temperature. One major metabolite fraction was observed accounting for 0.4% and 2.3% of the radioactivity in the edible and non-edible fish parts of higher exposure concentration (Cl), respectively and for 3.2% of the radioactivity in the non-edible fish parts of lower exposure concentration (C2). Based on the metabolites identified the metabolism of the test substance in Bluegill Sunfish proceeds via oxidation reactions at various positions, followed by conjugation with acid, glucuronic acid or taurine.

Details on results:

- Purity of the stock solutions: An aliquot of the stock solution 1 (SL1) of 14C-labelled test substance was submitted to HPLC analysis 12 days before start of the accumulation phase. No impurities (UV-LOQ = 0.02 mg/L) were detected, using UV/VlS-detection; the content of the test item was 100.4% of the nominal concentration (19250 mg/L). The analysis of the radio signal (C14-LOQ = 800 dpm/injection) showed a radiochemical purity of 100 %.
An aliquot of the stock solution 2 (SL2) of unlabelled the test substance was submitted to HPLC-analysis 12 days before start of the accumulation. No impurities ( LOQ = 0.02 mg/L) were detected; the content of the test item was 104.2 % of the nominal concentration.
An aliquot of the stock solution 3 (SL3 = mixture of SL1 and SL2) was submitted to HPLC-analysis 12 days before start of the accumulation phase. No impurities (UV-LOQ = 0.02 mg/L) were detected using UV/VIS-detection; the content of the test item was 98% of the nominal concentration (38500 mg/L). The analysis of the radio signal (C14-LOQ = 800 dpm/injection) showed a radiochemical purity of ≥ 100%. The 2d-TLC chromatogram showed a radiochemical purity of 100% 6 days after start of accumulation.

- Distribution of Radioactivity in Water: The concentration of the test substance equivalents in water during the accumulation phase ranged from to 0.0160 mg equiv./L with an average of 0.0145 ± 0.00077 mg for the higher concentration (C1). For the lower concentration (C2) the concentration of the test substance ranged from 0.00134 to 0.00159 mg with an average of 0.00144 ± 0.00008 mg equiv./L. The levels of radioactivity measured the first day of depuration rapidly dropped to 150 ng equiv./L for the higher and < 10 ng equiv./L for the lower concentration, respectively. From the third day of depuration, no radioactivitity could be measured in both test concentrations.

- Identification of Substances in Water: The nature of the test item and its concentrations in water specimens of the treated tanks was demonstrated by HPLC-analysis at sampling days -4, -l, 0, l, 3, 7, 14, 17, 21, 24 and 28 of the exposure phase. The HPLC-chromatograms of the test specimens showed no interference with other peaks. The identity of the parent molecule was proven by co-chromatography. The composition of water specimens was also tested by two dimensional thin layer chromatography (2d-TLC)-analysis for C1 at sampling days 7 and 28. The content of 14C-labelled test substance in both specimens was 100% in relation to the total radiolabelled material in the specimen. As shown by 2d-TLC, there was no interference of the parent molecule with the main metabolites M1. M2 and M3.

- Distribution of Radioactivity in Fish: Based on the total radioactivity found in the different fish tissues, the kinetic data were evaluated using a steady-state approach.
The test substance residues were rapidly concentrated in edible and non-edible portions of the fish as well as in the whole fish. The concentrations reached a constant plateau after approximately 17 days for both the higher (C 1) and the lower concentration (C2).
At steady state, the concentration of the test item in the whole fish was within 20% of the mean steady state concentration for at least 4 successive specimens at intervals of at least 3 days for both, the higher (C1) and the lower concentration (C2).
At steady state, the measured concentrations of the test substance equivalents in the non-edible and edible tissues and in the whole fish were 11.3, 1.71 and 6.86 mg equivalents/kg tissue fresh weight for the higher concentration (C1) and 1.39, 0.169 and 0.825 mg equivalents/kg tissue fresh weight for the lower concentration (C2), respectively.
After termination of exposure, the test substance residues were rapidly eliminated from the non-edible and edible tissues and the whole fish with DT90 values of 1.8, 1.8 and 2.0 days for the higher concentration (C1) and 4.0, 1.3 and 3.7 days for the lower concentration (C2). The data of the exposure- and depuration phase indicate that, under constant exposure, the test substance will be bioconcentrated mainly in non-edible fish tissues. Elimination of the bioconcentrated residues is ≥ 89% after 3 days and 95% after 10 days in the test substance free water.

- Lipid Determination: The lipid content of the fish was determined gravimetrically after solvent extraction of the edible and non-edible tissues days 0, 28 and 42. The lipid amount of the whole fish was calculated from the results of the edible and non-edible parts. The lipid content (% of weight) of the edible parts was within the range of 1.5% (day 0, control) to 3.7% (day 42, control) for all, control fish, low dose fish and high dose fish. The lipid content of the non-edible parts was
within the range of 4.0% (day0, control) to 7.2% (day 42, control) for all, control fish, low dose fish and high dose fish.
The calculated lipid content (% of weight) of total fish at days 0, 28 and 42, was within the range of 2.8% to 5.6% for control fish and 3.3% to 3.4% for both, low dose and high dose fish.
At day 28 the lipid content (% of weight) was 1.9% and 4.4% in the edible and non-edible parts, respectively, for the high dose (C1) fish and 2.2% and 4.6% for the low dose (C2) sh. Therefore the lipid content was independent of the exposure dose.

- Estimation of Bioconcentration factors: Bioconcentration factors (BCFs) were determined by calculating the ratio of the steady-state concentration of the test substance equivalents in fish tissues and whole fish to the average concentration of the test substance in water during steady-state (measured BCF, based on total radioactivity). In addition, bioconcentration factor for the same tissues were estimated calculating the ratio of the uptake rate constant to the depuration rate constant (calculated BCF). The measured bioconcentration factor for the test substance equivalent residues in non-edible portions, edible portions and the whole fish were 769, 116 and 467 for the higher, and 959, 117 and 569 for the lower concentration, respectively. Thus, the mean measured BCF for the test substance is 518 for the whole fish. The BCFs from the kinetic data for the same tissues were 823, 117 and 495 for the higher concentration (C1) and 1030, 110 and 591 for the lower concentration (C2), respectively, giving a mean calculated BCF of 543 for the whole fish. Bioconcentration factors, calculated for parent compound were based on the metabolite pattern in fish tissues at day 28 of the accumulation. The bioconcentration factors for parent compound in non-edible portions, edible portions and the whole fish were 138, 80 and 112, for the higher (C1), and 151, 70 and 120 for the lower concentration (C2), respectively. Thus, the mean BCF for parent compound is 116 for the whole fish. The course of the accumulation and depuration and the BCF’s determined in the present experiment indicate only a limited bioconcentration of the test substance in the bluegill, Lepomis macrochirus.

Table 1. Level of Radioactivity in Water During Exposure and Depuration

A. Nominal concentration: 0.015 mg/L

Period	Incubation (days)	Test substance (mg/L)
	-4	0.015
	-1	0.0163
	0	0.0142
	1	0.0148
	2	0.015
	3	0.0144
	7	0.016
	9	0.0143
	13	0.013
	14	0.0138
	17	0.0138
	21	0.0149
	24	0.0149
	28	0.015
	Average accumulation	0.0145
	Average steady state	0.0147
Depuration	29	0.00015
	30	0.00003
	31	0.00000
	35	0.00000
	38	0.00000
	42	0.00000

 

B. Nominal concentration: 0.0015 mg/L

Period	Incubation (days)	Test substance (mg/L)
	-4	0.00150
	-1	0.00153
	0	0.00139
	1	0.00144
	2	0.00150
	3	0.00136
	7	0.00159
	9	0.00143
	13	0.00136
	14	0.00134
	17	0.00145
	21	0.00150
	24	0.00149
	28	0.00137
	Average accumulation	0.00144
	Average steady state	0.00145
Depuration	29	0.00000
	30	0.00000
	31	0.00000
	35	0.00000
	38	0.00000
	42	0.00000

 

 

Table 2.Level of Radioactivity in Fish Tissues

A. Nominal concentration: 0.015 mg/L

	Time	Edibles (mg/kg)	non-edibles (mg/kg)	Total (mg/kg)
Accumulation	0	0.49	1.05	0.766
	1	1.31	9.14	5.23
	3	1.33	9.61	5.76
	7	1.9	11.3	6.55
	14	1.73	16.7	10
	17	1.51	11	6.54
	21	1.7	11.6	7.34
	24	1.58	10.9	6.52
	28	2.05	11.8	7.04
Depuration	29	0.36	3.02	1.8
	31	0.11	0.85	0.5
	35	0.09	0.64	0.38
	38	0.07	0.55	0.33
	42	0.06	0.43	0.25
Average at steady-state (Sampling days 17 -28)		1.71	11.3	6.86
Bioaccumulation factors
Steady-state from day 17 to day 28
Average concentration in water: 0.0147 mg/L
	Edibles	Non-edibles	Total
Measure (Ctissue/Cwater)	116	769	467

 

B. Nominal concentration: 0.0015 mg/L

	Time	Edibles (mg/kg)	non-edibles (mg/kg)	Total (mg/kg)
Accumulation	0	0.054	0.105	0.079
	1	0.132	0.783	0.491
	3	0.130	1.06	0.600
	7	0.145	1.50	0.848
	14	0.152	1.89	0.998
	17	0.133	1.29	0.741
	21	0.166	1.45	0.860
	24	0.179	1.54	0.915
	28	0.196	1.27	0.782
Depuration	29	0.021	0.37	0.200
	31	0.014	0.15	0.087
	35	0.01	0.08	0.046
	38	0.009	0.07	0.042
	42	0.007	0.06	0.033
Average at steady-state (Sampling days 17 -28)		0.169	1.39	0.825
Bioaccumulation factors
Steady-state from day 17 to day 28
Average concentration in water: 0.00145 mg/L
	Edibles	Non-edibles	Total
Measure (Ctissue/Cwater)	117	959	569

  

Table 3. Bioconcentration Factors

A. Nominal concentration : 0.015 mg/L

Steady-state from day 7 to day 28
Average concentration in Edible portions:	1.17 mg/kg
Average concentration in non-Edible portations:	11.3 mg/kg
Average concentration in fish:	6.86 mg/kg
Average Concentration in Water (day 17 - 28)	0.147 mg/L
BCF based on the test substance equivalents	Edibles	non-edibles	Total
Measured (Ctissue/Cwater):	116	769	467
Calculated (Ku/Kd):	117	823	495
BCF calculated for parent compound, on day 28	Edibles	non-edibles	Total
BCF on day 28	80	138	112

 

B. Nominal concentration : 0.0015 mg/L

Steady-state from day 7 to day 28
Average concentration in Edible portions:	0.169 mg/kg
Average concentration in non-Edible portations:	1.39 mg/kg
Average concentration in fish:	0.825 mg/kg
Average Concentration in Water (day 17 - 28)	0.00145 mg/L
BCF based on the test substance equivalents	Edibles	non-edibles	Total
Measured (Ctissue/Cwater):	117	959	569
Calculated (Ku/Kd):	110	1030	591
BCF calculated for parent compound, on day 28	Edibles	non-edibles	Total
BCF on day 28	70	151	120

C. Mean from both test concentrations

Mean BCF based on the test substance equivalents	Edibles	non-edibles	Total
Measured (Ctissue/Cwater):	117	864	518
Caclulcated (Ku/Kd):	113	927	543
Mean BCF calculated for parent compound, on day 28	Edibles	non-edibles	Total
BCF on day 28	75	145	116

 

Table 4. Calculated Depuration Times

A. Nominal Concentration: 0.015 mg/L

Depuration time based on the test substance equivalents (days)
	Edibles	Non-Edibles	Total
DT-50	0.53	0.53	0.62
DT-90	1.8	1.8	2.0

 

B. Nominal Concentration: 0.0015 mg/L

Depuration time based on the test substance equivalents (days)
	Edibles	Non-Edibles	Total
DT-50	0.40	1.2	1.1
DT-90	1.3	4.0	3.7

 

C. Mean from both test concentrations

Depuration time based on the test substance equivalents (days)
	Edibles	Non-Edibles	Total
DT-50	0.47	0.87	0.87
DT-90	1.6	2.9	2.9

 

Validity criteria fulfilled:

yes

Remarks:

See validity of the study in 'Any other information on materials and methods incl. tables'

Conclusions:

In a bioaccumulation study in bluegill sunfish, in accorfdance with EPA165-4 and under GLP, based on the findings, the kinetic BCFs were determined to be 112 and 120 L/kg in whole fish for 0.015 mg/L and 0.0015 mg/L treatments, respectively. The 5% normalized BCFs were calculated to be 185 and 193 L/kg in whole fish for 0.015 mg/L and 0.0015 mg/L treatments, respectively. The DT90 of the substance was 2.0 - 3.7 days, depending on the treated concentration.

Executive summary:

The bioaccumulation potential of the 14C-labelled test substance was investigated in a flow-through study in accordance with EPA165-4 guideline and in compliance with GLP criteria. In this study, bluegill sunfish (Lepomis macrochirus) were exposed to radiolabelled test substance at concentrations of 0.0015 and 0.015 mg/L for 28-day (uptake phase, 100 fish per concentration). Afterwards, fish were transferred to aquaria without the test substance in a 14-day depuration phase. Specific activities were confirmed by using HPLC. The test condition was maintained at average pH 8.1 and 22.1 °C. The water hardness was 9.7 mg/L (as CaCO3) and the O2 concentration at 94% saturation level.

The test substance residues were rapidly concentrated in the edible and non-edible portions of the fish, reaching a constant plateau after 17 days for the higher and the lower concentration. At steady state, the measured concentrations of the test substance equivalents in the non-edible and edible tissues and in the whole fish were 11.3, 1.71 and 6.86 mg equivalents/kg tissue fresh weight for the higher concentration and 1.39, 0.169 and 0.825 mg equivalents/kg tissue fresh weight for the lower concentration, respectively. The measured bioconcentration for the test substance equivalent residues in non-edible portions, edible portions and the whole fish were 769, 116 and 467 for the higher, and 959, 117 and 569 for the lower concentration, respectively. Thus, the mean measured BCF for the test substance was 518 for the whole fish. The calculated BCFs from the kinetic data for the same tissues were 823, 117 and 495 for the higher concentration (C1) and 1030, 110 and 591 for the lower concentration (C2), respectively, giving a mean calculated BCF of 543 for the whole fish. The bioconcentration factors, taking into account the analysed residues on day 28 of uptake, in non-edible portions, edible portions and the whole fish were 138, 80 and 112, for the higher (C1), and 151, 70 and 120 for the lower concentration (C2), respectively. Thus, the mean BCF for parent was 116 for the whole fish. For lipid normalization of the kinetic BCF, mean lipid content was calculated using the values determined at the start and the end of the study. The mean lipid content of the whole fish at the start of the study was 2.80%. At the end of the study, the mean lipid contents of the whole fish were 3.26% and 3.42% for high and low exposed concentrations, respectively. Thus, the 5% normalized BCFs were calculated to be 185 and 193 L/kg in whole fish for 0.015 mg/L and 0.0015 mg/L treatments, respectively. In addition, the test substance residues were rapidly eliminated from the whole fish with DT90 values of 2.0 days and 3.7 days for the high and low tested concentrations. In conclusion, the test substance showed only limited bioconcentration in bluegill, and elimination of the bioconcentrated residues was 89% after 3 days and 95% after 10 days in the test substance free water.

Description of key information

BCF = 193 L/kg, whole fish, Lepomis macrochirus, aqueous, freshwater, EPA 165 -4, Volz 2001

Key value for chemical safety assessment

BCF (aquatic species):

193 L/kg ww

Additional information

The bioaccumulation potential of the 14C-labelled test substance was investigated in a flow-through study in accordance with EPA165-4 guideline and in compliance with GLP criteria. In this study, bluegill sunfish (Lepomis macrochirus) were exposed to radiolabelled test substance at concentrations of 0.0015 and 0.015 mg/L for 28-day (uptake phase, 100 fish per concentration). Afterwards, fish were transferred to aquaria without the test substance in a 14-day depuration phase. Specific activities were confirmed by using HPLC. The test condition was maintained at average pH 8.1 and 22.1 °C. The water hardness was 9.7 mg/L (as CaCO3) and the O2 concentration at 94% saturation level.

The test substance residues were rapidly concentrated in the edible and non-edible portions of the fish, reaching a constant plateau after 17 days for the higher and the lower concentration. At steady state, the measured concentrations of the test substance equivalents in the non-edible and edible tissues and in the whole fish were 11.3, 1.71 and 6.86 mg equivalents/kg tissue fresh weight for the higher concentration and 1.39, 0.169 and 0.825 mg equivalents/kg tissue fresh weight for the lower concentration, respectively. The measured bioconcentration for the test substance equivalent residues in non-edible portions, edible portions and the whole fish were 769, 116 and 467 for the higher, and 959, 117 and 569 for the lower concentration, respectively. Thus, the mean measured BCF for the test substance was 518 for the whole fish. The calculated BCFs from the kinetic data for the same tissues were 823, 117 and 495 for the higher concentration (C1) and 1030, 110 and 591 for the lower concentration (C2), respectively, giving a mean calculated BCF of 543 for the whole fish. The bioconcentration factors, taking into account the analysed residues on day 28 of uptake, in non-edible portions, edible portions and the whole fish were 138, 80 and 112, for the higher (C1), and 151, 70 and 120 for the lower concentration (C2), respectively. Thus, the mean BCF for parent was 116 for the whole fish. For lipid normalization of the kinetic BCF, mean lipid content was calculated using the values determined at the start and the end of the study. The mean lipid content of the whole fish at the start of the study was 2.80%. At the end of the study, the mean lipid contents of the whole fish were 3.26% and 3.42% for high and low exposed concentrations, respectively. Thus, the 5% normalized BCFs were calculated to be 185 and 193 L/kg in whole fish for 0.015 mg/L and 0.0015 mg/L treatments, respectively. In addition, the test substance residues were rapidly eliminated from the whole fish with DT90 values of 2.0 days and 3.7 days for the high and low tested concentrations. In conclusion, the test substance showed only limited bioconcentration in bluegill, and elimination of the bioconcentrated residues was 89% after 3 days and 95% after 10 days in the test substance free water.