picoxystrobin (ISO); methyl (2E)-3-methoxy-2-[2-({[6-(trifluoromethyl)pyridin-2-yl]oxy}methyl)phenyl]acrylate

Bioaccumulation: aquatic / sediment

Link to relevant study record(s)

Reference

Reference 1

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 C (Bioaccumulation: Test for the Degree of Bioconcentration in Fish)

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

99.8% purity

Radiolabelling:

yes

Details on sampling:

The sample of radiolabelled test substance used for the definitive study was received at Brixham Environmental Laboratory on 22 August 1997 and assigned the Brixham test substance number AD0575. The radiochemical data sheet stated that the sample's total activity was 326.67 MBq. The specific activity of the sample was quoted to be 1.1 GBq mmol/L (3000 Bq/μg). The solubility of the technical test substance in purified water is quoted to be 3.1 mg/L at 20°C.

Vehicle:

yes

Remarks:

trigol

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

A single nominal radiolabelled test substance concentration, 5.0 μg/L , and a solvent control were used in the study. The radiolabelled test substance was continuously dosed into the test vessel from a stock solution made up in trigol. The sample of radiolabelled test substance (specific activity 3000 Bq/μg) was dissolved in 100 mL of a 1:1 v/v ratio mix of methyl-tert-butyl ether: hexane. Stock solutions for the nominal 5.0 μg/L test concentration required 60 MBq of radiolabelled test substance which was equivalent to 18.4 mL of the prepared solution (determined from known specific activity and the required stock solution concentration - 50 mg/L). The required quantity of this stock solution was pipetted into a 500 mL glass jar and the solvent evaporated under nitrogen. The residue was redissolved in 400 ml trigol (equivalent to 450 g trigol, calculated from density of 1.125 g/mL). The total activity of the final stock solution was then determined accurately using the exact trigol addition weights and measured specific activity determinations (liquid scintillation counting). The stock solution was placed in a 500 mL glass jar. Similarly 400 mL trigol was added to a glass jar to act as the solvent control stock solution. A magnetic follower was added to each jar. The jars were then weighed and placed on the test rig and the magnetic stirrers started. The stock solutions were delivered at a nominal flow rate of 0.0360 mL/min to the mixing chambers. The flow rates of the stock solutions and of the dilution water were measured on day 0 and thereafter three times per week. The first stock solution was prepared on day 5. Subsequently new stock solutions were prepared every 7 days, a total of five times during the study. The solvent control test solution contained 100 μL/L of trigol, which was the level used in the treated test concentration.

Test organisms (species):

Lepomis macrochirus

Details on test organisms:

The fish were obtained from Aquatic Research Organisms, 1, Lafayette Road, Hampton, New Hampshire 03842, USA and arrived at Brixham Environmental Laboratory on 11 September 1997. The pretest diet used for the fish was Keystart 1200, a proprietary product fed daily. The fish were fed the same diet (batch Ref FF400) during the exposure and depuration periods of the study. The batch of fish used for this study (batch Ref 97 /64) was held at 22 ± 1°C since arrival at Brixham Environmental Laboratory. The fish were held in glass aquaria under artificial lighting. No medication was given to the fish prior to the study. The fish were considered to be in good condition as the last, single, mortality took place on 2 October 1997, six days before exposure day 0. 128 Bluegill sunfish were used in the treated and solvent control tanks. On day 0 the mean weight and length of the stock population was determined by measurement of 4 individuals prior to introduction to the tanks. The range in weight was 0.75 to 1.75 g with a mean of 1.21 g and the range in length was 37.0 to 41.1 mm with a mean of 39.0 mm. Half of the fish (64) in each tank were also bulk weighed after introduction to determine the feeding rates. The mean weight in the solvent control tank was 1.56 g, in the exposure tank it was 1.59 g.

Route of exposure:

aqueous

Justification for method:

aqueous exposure method used for following reason: Determination of bioaccumulation and depuration

Test type:

flow-through

Water / sediment media type:

natural water: freshwater

Total exposure / uptake duration:

28 d

Total depuration duration:

14 d

Hardness:

45.2 as CaCO3 (Mean; Range 39.3 to 53.3)

Test temperature:

22 ± l°C (Mean; Ranged 21.8 to 22.4°C)

pH:

Minimum 7.53 and Maximum 7.76

Dissolved oxygen:

Dissolved oxygen levels ranged from 7.0 to 8.6 mg/L

Conductivity:

210 µs/cm (Mean; Range 199-221 µs/cm)

Details on test conditions:

The test was conducted at 22 ± 1°C with a photoperiod of 16 hours light:8 hours dark with 20 minute dawn and dusk transition periods. The test system was illuminated by "cool" white fluorescent lights situated above the tanks. The light intensity was measured by cosine receptor. These measurements were made midway between the front and back of the apparatus, using a Skye Instruments unit SKL300 photometer with a matching sensor head type SKL310. Readings were taken at the centre and near the two ends of the apparatus to determine the range of values along the length of the apparatus.

The population of fish in each tank were fed Keystart 1200 (FF400), a proprietary fish food at a rate of 2% of the total fish weight per day. The total weight of fish in each tank was estimated from the weight of sampled fish on exposure days 0, 14 and 28 after which an adjustment was made to the quantity of food dispensed. The product Keystart 1200 is described by the suppliers as containing 55.0% protein, 16.0% oil and 8.5% ash and 1 % fibre. The batch of food was analysed for pesticides by Trouw Nutrition, Wincham, Northwich, Cheshire, CW9 6DF, UK, which is a non Good Laboratory Practice (GLP) compliant laboratory but is registered to BS5750 and IS09000. The reports of their analytical results are archived at Brixham Environmental Laboratory. The food was also analysed for heavy metals, at Brixham Environmental Laboratory where the results are archived.

Nominal and measured concentrations:

5.0 µg/L (Nominal) and 4.6 µg/L (Analytical; Range 4.4 to 4.9 µg/L)

Reference substance (positive control):

no

Details on estimation of bioconcentration:

The BCFs were calculated for each separate tissue and for whole fish as follows:

BCF concentration of radiolabeled test substance equivalents in tissue (wet weight)/concentration of radiolabeled test substance equivalents in water

The calculations were based on measured tissue concentrations and mean measured concentration in the single 5.0 μg/L test solution. The BCF values were also calculated on the basis of the lipid content of the whole fish.

Lipid content:

15 745 µg/kg bw w.w.

Time point:

other: Mean of concentration recorded on days 7, 14, 21, and 28

Remarks on result:

other: Whole body

Key result

Conc. / dose:

5 µg/L

Temp.:

22.1 °C

pH:

7.53

Type:

BCF

Value:

1 400 dimensionless

Basis:

other: Viscera

Time of plateau:

5 d

Key result

Conc. / dose:

5 µg/L

Temp.:

22.1 °C

pH:

7.53

Type:

BCF

Value:

110 dimensionless

Basis:

other: Flesh

Time of plateau:

5 d

Key result

Conc. / dose:

5 µg/L

Temp.:

22.1 °C

pH:

7.53

Type:

BCF

Value:

170 dimensionless

Basis:

other: Carcass

Time of plateau:

5 d

Key result

Conc. / dose:

5 µg/L

Temp.:

22.1 °C

pH:

7.53

Type:

BCF

Value:

290 dimensionless

Basis:

whole body w.w.

Time of plateau:

5 d

Key result

Elimination:

yes

Parameter:

other: 55%

Depuration time (DT):

24 h

Key result

Elimination:

yes

Parameter:

other: 86%

Depuration time (DT):

14 d

Key result

Rate constant:

overall depuration rate constant (d-1)

Value:

0.63

Validity criteria fulfilled:

yes

Conclusions:

The mean plateau BCF value for the whole body was 290.

Executive summary:

Bluegill sunfish were exposed for 28 days to 5.0 µg/L of the radiolabeled test substance with a depuration period of 14 days. The test was conducted according to OECD guideline 305C. BCF values were 1400 for the viscera, 110 for flesh, 170 for carcass, and 290 for whole body. The depuration of accumulated residues from the whole body was rapid with approximately 55% depuration within 24 hours and 86% depuration within 14 days. The uptake rate constant was calculated to be 181/day and the depuration rate constant was calculated to be 0.63/day.

Reference 2

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 (Bioconcentration: Flow-through Fish Test)

Deviations:

no

GLP compliance:

yes

Radiolabelling:

yes

Remarks:

14C-Phenylacrylate labelled

Details on sampling:

- Sampling intervals/frequency for test organisms: Fish samples were collected on Day 21 and 28 of Acculmulation phase and Day 14 of Depuration phase (20 fish samples at each time-point)
- Sampling intervals/frequency for test medium samples: Water samples were collected on Day 24, 25, 26, 27 and 28 of Acculmulation phase
- Details on sampling and analysis of test organisms and test media samples: Sampled fish were killed by placing them in a solution of 500 μg/L solution of MS-222 (a proprietary fish anesthetic). Any excess solution on the surface of the fish was removed by blotting dry and the fresh weight and length of individual fish were recorded. The samples were stored in freezer at -22.5 ± 2.5°C.

Test organisms (species):

Lepomis macrochirus

Details on test organisms:

TEST ORGANISM
- Common name: Bluegill sunfish
- Strain: Lepomis macrochirus
- Source: Aquatic Research Organisms, 1, Lafayette Road, Hampton, New Hampshire 03842, U.S.A.
- Length at study initiation: 37.0 to 41.1 mm with a mean of 39.0 mm
- Weight at study initiation: 0.75 to 1.75 g with a mean of 1.21 g

Route of exposure:

aqueous

Justification for method:

aqueous exposure method used for following reason: Determination of bioaccumulation and depuration

Test type:

flow-through

Water / sediment media type:

natural water: freshwater

Total exposure / uptake duration:

28 d

Total depuration duration:

14 d

Nominal and measured concentrations:

4.1 µg/L (concentration of total radioactivity)

Reference substance (positive control):

no

Key result

Conc. / dose:

4.1 µg/L

Type:

BCF

Value:

740 dimensionless

Basis:

other: Viscera

Remarks on result:

other: Plateau residues: 3034 µg/Kg (mean of 21 and 28 day exposure residues)

Key result

Conc. / dose:

4.1 µg/L

Type:

BCF

Value:

70 dimensionless

Basis:

other: Muscle

Remarks on result:

other: Plateau residues: 289 µg/Kg (mean of 21 and 28 day exposure residues)

Key result

Conc. / dose:

4.1 µg/L

Type:

BCF

Value:

131 dimensionless

Basis:

other: Remainder

Remarks on result:

other: Plateau residues: 536 µg/Kg (mean of 21 and 28 day exposure residues)

Key result

Conc. / dose:

4.1 µg/L

Type:

BCF

Value:

162 dimensionless

Basis:

other: Whole fish

Remarks on result:

other: Plateau residues: 665 µg/Kg (mean of 21 and 28 day exposure residues)

Key result

Elimination:

yes

Parameter:

other: % depuration of degradates: 96.1%

Depuration time (DT):

14 d

Remarks on result:

other: Viscera

Key result

Elimination:

yes

Parameter:

other: % depuration of degradates: 73.3%

Depuration time (DT):

14 d

Remarks on result:

other: Muscle

Key result

Elimination:

yes

Parameter:

other: % depuration of degradates: 78.6%

Depuration time (DT):

14 d

Remarks on result:

other: Remainder

Key result

Elimination:

yes

Parameter:

other: % depuration of degradates: 85.1%

Depuration time (DT):

14 d

Remarks on result:

other: Whole fish

Conclusions:

From this residue information it was concluded that for 14 day depuration tissues:
• No residues of 14C-test substance or its degradate compounds (previously identified in plateau phase exposure tissues) were detected indicating their complete elimination from exposure fish tissues during the 14 day depuration period.
• Only trace levels of identified compounds ZA1963/12 (≤0.8% TRR; ≤0.001 mg/kg) and ZA1963/14 (≤2.7% TRR; ≤0.003 mg/kg) were detected in all tissues.
• The nature of the remaining radioactive residues in all tissues comprised a complex mixture of predominantly very polar water soluble unassigned radio-degradate components or fractions, no individual associated residue of which accounted for greater than 44.9% TRR (0.059 mg/kg).

Executive summary:

Bluegill sunfish (Lepomis macrochirus) were exposed to 14C-test substance dissolved in water. The concentration of total radioactivity in the water was 4.6 µg/L and for 14C-test substance was 4.1 µg/L. Radioactive residues of 14C-test substance in viscera, muscle, remainder and whole fish were found to bio-concentrate to plateau levels as summarized in the table below. 

Tissue Type	Plateau Residue of 14C-test substance in Tissue (µg/kg)	Bio-concentration Factor (BCF 14C-test substance)
Viscera	3034	740
Muscle	289	70
Remainder	536	131
Whole Fish	665	162

BCF 14C-test substance = Plateau residue of 14C-test substance in tissue / Concentration of 14C-test substance in exposure water.

After transfer of the fish to water only, for a period of 14 days, 100% depuration of 14C-test substance was effected (i.e. no residues of 14C-test substance were detected in any of the tissues of depuration fish).

14C-test substance was the largest individual radio-component present in fish tissues during the plateau phase of exposure, accounting for at least 37.4% of the total radioactive residue (%TRR) in all tissues (44.0%TRR in viscera, 37.4%TRR in muscle, 45.6%TRR in remainder and 42.5%TRR in whole fish; the means of 21 day and 28 day exposure fish values).

The remainder of the radioactive residue present in these tissues comprised a very complex mixture of 14C-test substance degradate radio-components which were almost totally eliminated during the subsequent 14-day depuration period as demonstrated in the summary table below.

	Exposure Tissues		Depuration Tissues
Tissue Type	Percentage of Tissue TRR Attributable to 14C-test substance Degradates	Radioactive Residue Attributable to 14C-test substance Degradates (mg/Kg) A	Total Radioactive Residue in Tissues After 14 Days Depuration (mg/kg) B	% Depuration of 14C-test substance Degradates ([A-B]/A)x100
Viscera	56.2	3.842	0.150	96.1
Muscle	62.7	0.486	0.130	73.3
Remainder	54.7	0.641	0.137	78.6
Whole Fish	57.7	0.902	0.134	85.1

Bluegill sunfish (Lepomis macrochirus) tissues therefore bio-accumulate 14C-test substance to plateau concentration levels when the fish are exposed to the compound in water over a 28 day period, but after transfer to water containing no 14C-test substance for 14 days:

• total depuration of accumulated residues of 14C-test substance is effected from all tissues and

• almost total depuration of 14C-test substance degradate residues to very low terminal residue levels is effected in all tissues.

Description of key information

The BCFs (based on total radioactive residue) in fish viscera, muscle, remainder, whole body and lipid content were 1400, 110, 170, 290 and 3400 respectively. The uptake rate constant for 14C-test substance by bluegill sunfish was 181/day and the depuration rate constant was 0.63/day.

Key value for chemical safety assessment

BMF in fish (dimensionless):

290