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Environmental fate & pathways

Bioaccumulation: aquatic / sediment

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Reference
Endpoint:
bioaccumulation in aquatic species: fish
Remarks:
The bioconcentration test was conducted solely to comply with non-EU national registration requirements.
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From 12 September 2013 to 22 October 2013
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 305 (Bioconcentration: Flow-through Fish Test)
GLP compliance:
yes (incl. certificate)
Radiolabelling:
no
Details on sampling:
Water samples were collected daily during the equilibration phase and during the first eight days of the uptake phase. Thereafter water samples were taken every two days. Additionally, a sample was taken at the end of the exposure phase after the exchange of the water before adding the fish (sample day 14 without test item). During the depuration phase water samples were taken on days 15 and 17. Representative control water samples were analyzed for test item (day -7, 0, and 14).
Vehicle:
yes
Details on preparation of test solutions, spiked fish food or sediment:
Considering the low solubility of the test item in purified water, stock solution and application solution were prepared in dimethylformamide (DMF).
Stock solution: 200 mg of the test item was dissolved in 100 mL of DMF (target concentration 2.0 mg/mL).
The application solution (0.2 mg/mL) was then prepared by diluting 84 mL of the stock solution to 840 ml DMF. The remaining stock solution was stored at approximately -20°C.
Appropriate portions (3-day and 4-day portions) of the application solution corresponding to 5 mg/day (20 μg/L) were stored at approximately -20°C. The application solution was renewed every Tuesday and Friday of the exposure phase.
Test organisms (species):
Lepomis macrochirus
Details on test organisms:
Species: Bluegill sunfish (Lepomis macrochirus)
Source: Osage Catfisheries, Inc., Osage Beach, Missouri, USA
Acclimatisation period: At least three weeks.
Treatment for disease: N one reported
Weight and length of fish prior to exposure period: Mean weight: 2.39 g
Mean length: 5.4 cm
Feeding: T etraMin, Tetra GmbH, D-49304 Melle, containing 8.0% lipid and 48.0% total protein, once daily at a rate of 2 % of the average fish body weight per day taking into account increasing body weights and decreasing number of fish per tank.
Route of exposure:
aqueous
Test type:
flow-through
Total exposure / uptake duration:
14 d
Total depuration duration:
7 d
Hardness:
174.9 mg/L as CaCO3 (measured once on day 19 of exposure).
Test temperature:
19.7 – 24.6 oC
pH:
8.1 – 8.3
Dissolved oxygen:
5.5 – 9.4 mg/L
TOC:
<0.2(depuration period) – 33.5 – 41.3 mg/L (accumulation period)
Details on test conditions:
TEST SYSTEM
- Test vessel: tanks
- Material, size, headspace, fill volume:
- Aeration: yes
- Renewal rate of test solution (frequency/flow rate): 250 L/24hours
- No. of organisms per vessel: 118
- No. of vessels per concentration (replicates): one
- No. of vessels per control / vehicle control (replicates): one



OTHER TEST CONDITIONS
- Light intensity: 16 hours light and 8 hours dark, light intensity at light period approximately 500 Lux.

Nominal and measured concentrations:
Nominal concentration: 20 µg subst./L.
During the equilibration phase of 7 days, test item levels in the treated tank ranged from 19.11 to 22.01 µg subst./L (95.6 and 110.1% of nominal). During the accumulation period (days 0 to 14) in the exposure tank, the test item concentrations amounted on average to 17.50 ± SD 2.24 µg subst./L (79% to 114% of the mean measured concentration).
Reference substance (positive control):
no
Conc. / dose:
17.5 µg/L
Temp.:
>= 19.7 - <= 24.6 °C
Type:
BCF
Value:
111 dimensionless
Calculation basis:
steady state
Conc. / dose:
17.5 µg/L
Temp.:
>= 19.7 - <= 24.6 °C
Type:
BCF
Value:
111 dimensionless
Calculation basis:
kinetic
Conc. / dose:
17.5 µg/L
Temp.:
>= 19.7 - <= 24.6 °C
Type:
BCF
Value:
114 dimensionless
Calculation basis:
kinetic, corrected for growth
Elimination:
yes
Parameter:
DT50
Depuration time (DT):
1.4 d
Rate constant:
growth-corrected depuration rate constant (d-1)
Value:
0.508
Details on kinetic parameters:
- Uptake rate constant k(s):
- Depuration rate constant k(e):
Validity criteria fulfilled:
yes
Conclusions:
The measured BCFss and BCFk values obtained for whole fish were 111 and 111, respectively. The lipid normalised (to 5%) BCFL based on BCFSS and BCFk were 74 and 73, respectively.
Depuration half-life (t0.50) was calculated to be 1.4 days based on k2a. The time to achieve 99 % depuration (t0.99) was calculated to be 9.1 days.
Executive summary:

The bioconcentration and depuration characteristics of the test item in the Bluegill Sunfish were investigated by means of a dynamic flow-through system. The bioconcentration in whole fish was calculated.

The fish were continuously exposed under flow-through conditions to the test item at a mean measured concentration of 17.50 μg/L for 14 days. After the exposure, the fish were transferred to flowing untreated water and the depuration of the material was monitored for a further 7 days. Temperature, pH and oxygen concentrations were monitored from day 0 to day 21; measurements ranged from 19.7-24.6 °C, 8.1-8.3 and 5.5-9.4 mg/L, respectively.

The overall temperature variation was slightly outside the limit of ± 2 °C. At the start of depuration the temperature was recorded as 19.7 °C. No other measurements were below 20.5 °C. It can be assumed that this short temperature deviation had no adverse effect on the study results.

Concentration of the test item during exposure in whole fish increased rapidly to levels ranging from 1.620 to 2.299 μg/g for time intervals day 4 to day 10. Fish concentrations decreased slightly to 1.781 and 1.647 μg/g on day 12 and 14 respectively. Concentration of the test item during depuration rapidly decreased to 0.150 μg/g on day 15 (day 1 of depuration) to below the limit of detection level on day 17 (day 3 of depuration).

A steady state plateau level (CfSS) based on time intervals 7, 10, 12 and 14 was calculated to be 1.936 ± 0.286 μg/g. The plateau level obtained by non-linear parameter estimation amounted to 1.934 μg/g.

The results can be summarized as follows:


Parameter   Description  Values
 kg  growth rate constant; day-1  0.016
 k1  overall uptake rate constant L kg-1 day-1  57.9
k2a  overall depuration rate constant; day-1, based on accumulation data  0.524
 k2d  overall depuration rate constant; day-1, based on depuration data  2.369
 k2g  growth-corrected depuration rate constant; day-1  2.353
 Cfss  chemical concentration in fish at steady-state: μg g-1  1.936
 Cw  chemical concentration in the water mg L-1  17.50
 Ln  lipid normalisation factor  0.664
 BCFss  steady-state BCF; L kg-1  111
 BCFssl  lipid-normalised steady-state BCF; L kg-1  74
 BCFk  kinetic BCF; L kg-1  111
 BCFkl  lipid-normalised kinetic BCF; L kg-1  73
 BCFkg  growth-corrected kinetic BCF; L kg-1  114
 BCFklg  lipid-normalised growth-corrected kinetic BCF; L kg-1  76
 t0.5g  growth-corrected half-life; day  1.4

Description of key information

The fish embryo acute toxicity study was conducted solely to comply with a non-EU national registration requirements.

The measured BCFss and BCFk values obtained for whole fish were 111 and 111, respectively. The lipid normalised (to 5%) BCFL based on BCFSS and BCFk were 74 and 73, respectively.

Depuration half-life (t0.50) was calculated to be 1.4 days based on k2a. The time to achieve 99 % depuration (t0.99) was calculated to be 9.1 days.

Key value for chemical safety assessment

BCF (aquatic species):
111 dimensionless

Additional information