4,4,13,13-tetraethoxy-3,14-dioxa-8,9-dithia-4,13-disilahexadecane

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:

1999-06-24 to 1999-11-26

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, with acceptable restrictions. The restrictions were that HCO was used as dispersant, and the concentrations of the test substance were above the predicted water solubility (0.01 mg/l, see section 4.8). In addition, the analysis was performed by AA for Si and so it was not possible to determine whether parent or degradation product was measured.

Qualifier:

according to guideline

Guideline:

other: Method for Testing the Degree of Accumulation of Chemical Substances in Fish Body (MITI)

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 305 C (Bioaccumulation: Test for the Degree of Bioconcentration in Fish)

Deviations:

yes

Remarks:

HCO used as dispersant. Analysis performed by AA for Si so not possible to determine whether parent or degradation products measured.

GLP compliance:

yes (incl. QA statement)

Radiolabelling:

no

Details on sampling:

- Sampling intervals/frequency for test organisms: Concn in test fish analysed in weeks 2, 4, 6 and 8. Concn in control fish analysed at initiation and termination of exposure.

- Sampling intervals/frequency for test medium samples: Concn in water analysed twice a week.

Test organisms (species):

Cyprinus carpio

Details on test organisms:

TEST ORGANISM

- Source: Sugishima fish farm, Kumamoto 866-0024, Japan.

- Length at study initiation (lenght definition, mean, range and SD): av. 10.6cm

- Weight at study initiation (mean and range, SD): av. 25.7g

- Feeding during test
- Food type: Pelleted feed for Carp
- Amount: 2% total body weight twice a day in halves. On day before sampling, no feed given



ACCLIMATION
- Acclimation period: After rearing for one day, the fish were medicated to eliminate parasites and transferred to an acclimatizing aquarium, then to the test tanks and reared at 25 degC for 44d.

Route of exposure:

aqueous

Test type:

flow-through

Water / sediment media type:

natural water: freshwater

Total exposure / uptake duration:

8 wk

Test temperature:

25 ± 2 °C

Dissolved oxygen:

Level 1 7.1-7.8 mg/l
Level 2 7.4-8.0 mg/l
Control 6.9-7.7 mg/l

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Material, size, headspace, fill volume: 100 l glass tank

- Renewal rate of test solution (frequency/flow rate): 2 ml/min for stock solution; 800 ml/min for dilution water

- No. of organisms per vessel: 16 (2 in control)

Reference substance (positive control):

yes

Key result

Type:

BCF

Value:

49 - 347

Remarks on result:

other: Conc.in environment / dose:1 mg/l

Key result

Type:

BCF

Value:

146 - 715

Remarks on result:

other: Conc.in environment / dose:0.1 mg/l

Details on results:

No abnormality in behaviour or appearance of fish was noted.

 

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

	Duration of exposure	2 weeks	4 weeks	6 weeks	8 weeks
High concentration level	Concentration in the water (mg/l; two samples)	1.03; 1.3	1.01; 1.01	1.00; 1.00	1.01; 1.01
	Concentration in fish (µg/g; two samples)	357; 77.8	83.5; 103	87.1; 93.6	57.2; 50.0
	Bioconcentration factor	347; 76	83; 103	87; 93	56; 49
Low concentration level	Concentration in the water (mg/l; two samples)	0.0931; 0.0931	0.0905; 0.0905	0.0897; 0.0897	0.0883; 0.0883
	Concentration in fish (µg/g; two samples)	17.6; 13.6	23.6; 34.3	25.3; 64.1	14.4; 16.1
	Bioconcentration factor	189; 146	260; 380	282; 715	163; 183

 

Conclusions:

A mean BCF value of 290 for the lowest concentration tested was determined in a reliable study conducted according to an appropriate test protocol, with acceptable restrictions. The restrictions were that HCO was used as dispersant, and the concentrations of the test substance were above the predicted water solubility (0.01 mg/l, see section 4.8). In addition, the analysis was performed by AA for Si and so it was not possible to determine whether parent or degradation product was measured.

Description of key information

BCF = 146 to 715 measured at 2-8 weeks, 290 (mean of values at each sampling point for lower test concentration) (Method equivalent to or similar to OECD 305 C)

Key value for chemical safety assessment

BCF (aquatic species):

715 dimensionless

Additional information

A fish bioaccumulation study is available which used a method that is similar to OECD Test Guideline 305 C, with restrictions. Dispersant was used, and the concentrations of the test substance were above the predicted water solubility. Therefore, the results at the lowest concentration are likely to be most reliable.

 

A BCF value of 146 to 715 measured at 2-8 weeks, mean BCF value of 290 for the lowest concentration tested was determined in a reliable study conducted according to an appropriate test protocol, with acceptable restrictions. The restrictions were that a dispersant was used, and the concentrations of the test substance were above the predicted water solubility (0.014 mg/l, see section 4.8). In addition, the analysis was performed by atomic absorption for silicon and so it was not possible to determine whether the measured BCF is for the parent or degradation product. As a worst-case, the higher measured BCF of 715 is used for assessment purposes.

 

4,4,13,13-Tetraethoxy-3,14-dioxa-8,9-dithia-4,13-disilahexadecane (S2) hydrolyses at a moderate rate (half-life 40 - 80 h at pH 7 and 20-25°C, predicted) in contact with water to the corresponding silanol hydrolysis product and ethanol.

 

The silanol hydrolysis product and ethanol have low log Kow values (-3 and -0.3 respectively), and thus have low potential for bioaccumulation.