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Environmental fate & pathways

Bioaccumulation: aquatic / sediment

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Reference
Endpoint:
bioaccumulation in aquatic species: fish
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
The study was conducted according to an appropriate OECD test guideline. It was not compliant with GLP.
Qualifier:
according to
Guideline:
OECD Guideline 305 (Bioconcentration: Flow-through Fish Test)
GLP compliance:
no
Radiolabelling:
yes
Details on sampling:
Water was removed from the aquaria using 32-oz glass amber bottles, by submerging the bottle to approximately one-third depth of the water column, and allowing 500 ml of water to enter. Liquid Scintillation Counting carried out on triplicate 10-ml samples.
Fish were sampled one fish from each aquarium and treated as whole fish samples. On days 28 and 56 of the uptake phase, three additional fish, one from each aquarium in both control and treated levels, were pooled and dissected into fillet/edible and viscera/non edible. Fish were processed and homogenised. Triplicate analysis of samples using sample combustion followed by Liquid Scintillation Counting.
Details on preparation of test solutions, spiked fish food or sediment:
Stock solutions in acetone prepared.
High treatment: 10 000 mg/l
Low treatment: 1000 mg/l
Stock solutions were poured into a graduated cylinder directly hooked up to the Hamilton injector.
Test organisms (species):
Cyprinus carpio
Details on test organisms:
TEST ORGANISM
- Common name: Carp

- Source: Osage Catfisheries, Inc., in Osage Beach, Missouri.

- Length at study initiation (length definition, mean, range and SD): 98 ±5.9 mm

- Weight at study initiation (mean and range, SD): 28.7 ±6.0 g

- Weight at termination (mean and range, SD): High treatment level: 44.5 ±4.0 g; Low treatment group 53.0 ±9.5 g
Route of exposure:
aqueous
Test type:
flow-through
Water / sediment media type:
natural water: freshwater
Total exposure / uptake duration:
56 d
Total depuration duration:
14 d
Test temperature:
24 - 25 °C
pH:
High treatment 7.4 - 8.1; Low treatment 7.6 - 8.1
Dissolved oxygen:
High treatment 5.3 - 8.0 mg/l saturation; Low treatment 5.0 - 8.0 mg/l
Details on test conditions:
TEST SYSTEM
- Test vessel: 70-L glass aquaria

- Type: closed

- Type of flow-through (e.g. peristaltic or proportional diluter): proportional diluter

- Renewal rate of test solution (frequency/flow rate): 904-905 ml/minute/aquarium

- No. of organisms per vessel: Nine groups of 20 fish

- No. of vessels per concentration (replicates): Three

- No. of vessels per control / vehicle control (replicates): Three

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Aerated hard-blended water

RANGE-FINDING / PRELIMINARY STUDY
- Test concentrations: Nominal: 0.6, 1.3, 2.5, 5.0, 10 mg/l

- Results used to determine the conditions for the definitive study: no effects
Nominal and measured concentrations:
Nominal water concentrations: 1 mg/l; 0.1 mg/l

Mean measured water concentrations: 0.166 mg/l (±0.037); 0.0141 mg/l (±0.00339)
Reference substance (positive control):
no
Details on estimation of bioconcentration:
A nonlinear two-compartment kinetic modelling computer program (BIOFAC) was used to analyse the uptake/depuration whole fish data.
Key result
Type:
BCF
Value:
1 670 dimensionless
Basis:
whole body w.w.
Calculation basis:
kinetic
Remarks on result:
other: ±143
Remarks:
Conc.in environment / dose:0.166 mg/l
Key result
Type:
BCF
Value:
1 980 dimensionless
Basis:
whole body w.w.
Calculation basis:
kinetic
Remarks on result:
other: ±318
Remarks:
Conc.in environment / dose:0.0141 mg/l
Type:
BCF
Value:
1 450 dimensionless
Basis:
whole body w.w.
Calculation basis:
steady state
Remarks on result:
other: Conc.in environment / dose:0.166 mg/l
Type:
BCF
Value:
1 890 dimensionless
Basis:
whole body w.w.
Calculation basis:
steady state
Remarks on result:
other: Conc.in environment / dose:0.0141 mg/l
Key result
Parameter:
other: DT 50 (high treatment)
Depuration time (DT):
5.71 d
Key result
Parameter:
other: DT 50 low treatment
Depuration time (DT):
3.01 d
Details on kinetic parameters:
- Uptake rate constant (k1): High treatment: 203 (±13.5) mg/kg fish/mg/L water/day; Low treatment: 456 (±54.0) mg/kg fish/mg/L water/day
- Depuration (loss) rate constant (k2): High treatment: 0.121 (± 0.0065) day-1; Low treatment: 0.230 ( High treatment:0.0248) day-1
T (50%) for clearance, Day: High treatment: 5.71 (± 0.307); Low treatment: 3.01 (± 0.325)
Details on results:
High treatment tissue concentrations ranged from 134 to 1940 for whole fish. Low treatment tissues concentrations ranged from 2.13 to 30.2 mg/l for whole fish.

Table 1: Bioconcentration factors at different time points and concentrations in water

 

Duration of exposure (days)

0

0.17

1

3

7

14

21

28

35

42

49

56

High concentration level

Concentration in the water(mg/l)

0.148

0.152

0.155

0.119

0.219

0.197

0.164

0.188

0.180

0.119

0.158

0.193

Concentration infish (mg/kg)

N/A

10.9

45.2

101

205

302

209

226

282

208

212

272

Bioconcentration factor

-

72.7

297

701

1290

1830

1270

1350

1670

1270

1300

1640

Low concentration level

Concentration in the water(mg/l)

0.0166

0.0152

0.0165

0.0164

0.0152

0.0149

0.0136

0.0122

0.0139

0.0107

0.0087

0.0159

Concentration infish (mg/kg)

N/A

2.13

9.07

19.4

28.7

30.2

28.5

26.8

26.3

22.4

22.5

27.5

Bioconcentration factor

-

134

563

1200

1790

1910

1840

1770

1770

1540

1610

1940

 

 Table 2: Depuration

 

Days

1

3

7

10

14

High concentration level

Concentration in the water(mg/l)

<MQL

<MQL

<MQL

<MQL

<MQL

Concentration infish (mg/kg)

228

154

150

110

67.7

Bioconcentration factor

-

-

-

-

-

Low concentration level

Concentration in the water(mg/l)

<MQL

<MQL

<MQL

<MQL

<MQL

Concentration infish (mg/kg)

20.7

16.7

11.6

10.6

7.35

Bioconcentration factor

-

-

-

-

-

 

Validity criteria fulfilled:
yes
Conclusions:
BCFss values of 1450 (0.166 mg/l) and 1890 (0.0141 mg/l) and BCFk values of 1670 (0.166 mg/l) and 1980 (0.0141 mg/l) were determined in a reliable study conducted according to an appropriate test protocol, and in compliance with GLP.

Description of key information

Bioaccumulation [triethoxy(octyl)silane]: aquatic/sediment: BCFss 1450 (0.166 mg/L) and 1890 (0.0141 mg/L); BCFk 1670 ±143 (0.166 mg/L) and 1980 ±318 (0.0141 mg/L). The silanol hydrolysis product has a low potential for bioaccumulation.

Key value for chemical safety assessment

BCF (aquatic species):
1 890 dimensionless

Additional information

Steady-state BCF (BCFss) values of 1450 (0.166 mg/L) and 1890 (0.0141 mg/L), and kinetic BCF (BCFk) values of 1670 ±143 (0.166 mg/L) and 1980 ±318 (0.0141 mg/L) were determined in a reliable study conducted according to an appropriate test protocol, and in compliance with GLP.

Triethoxy(octyl)silane hydrolyses moderately (half-life approximately 30 h at 20-25°C and pH 7) to substances which have low log Kow values (<3) and thus have low potential for bioaccumulation.

Though the silanol hydrolysis product is expected to be surface active, the surface activity is weak and non-ionic. Therefore, it is considered appropriate to assume low potential for bioaccumulation based on log Kow.