Diisooctyl 2,2'-[(dioctylstannylene)bis(thio)]diacetate

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

27 July 1992 to 11 December 1992

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Remarks:

Study generally followed guideline, and met validity criteria. However, due to the insolubility of the test substance in the test medium, a constant factor between the test concentrations could not be achieved. It was not possible to determine an absolute EC50 (result is ≥ 100 mg/L) given that no inhibition was observed over the concentrations tested.

Reason / purpose for cross-reference:

other: read-across target

Qualifier:

according to guideline

Guideline:

other: Directive 87/302/EEC, part C, p. 118 (Biodegradation: Activated sludge respiration inhibition test)

Deviations:

yes

Remarks:

Instead of a centrifuged sludge a settled sludge was used. Due to the poor solubility of the test substance at test concentrations, no stock solution was prepared. The test substance was given directly into the medium. Therefore, a constant factor between

GLP compliance:

yes

Analytical monitoring:

no

Details on sampling:

No samples were taken for analysis of the test material concentration. Only oxygen concentration was measured.

Vehicle:

no

Details on test solutions:

20.1, 8.6, 3.9, 1.3, 0.6 and 0.3 mg of the test material were weighed and added to the test medium. The volume was adjusted to 200 mL with water and aerated for 3 hours. This produced test solutions of nominal concentrations of 100.5, 43.0, 19.5, 6.5, 3.0 and 1.5 mg/L. The sludge concentration in the test bottles was 1.60 g/L (dry weight) .

A reference compound (3,5-dichlorophenol) was also tested at 3 concentrations (32.0, 10.0, and 3.2 mg/L).

Test organisms (species):

activated sludge

Details on inoculum:

Activated sludge collected from the sewage treatment plant of CH-4153 Reinach On 28/09/92. The pH after collection was 7.0. The preparation was carried out according to the method described in the guideline. The sludge was separated from the aqueous layer by settling instead of centrifugation. The pH of the sludge before use was 7.8.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Post exposure observation period:

none.

Hardness:

Not stated

Test temperature:

Temperature was maintained at 20 ± 2°C

pH:

pH of the sluge before use was 7.8. After 3 hours aeration the pH was 8.3 in all blank, reference and test concentration samples except blank sample 1 which was 7.8.

Dissolved oxygen:

Not stated

Salinity:

Not applicable

Nominal and measured concentrations:

Test material: 100.5, 43.0, 19.5, 6.5, 3.0 and 1.5 mg/L

20.1, 8.6, 3.9, 1.3, 0.6 and 0.3 mg of the test material were weighed and added to the test medium. The volume was adjusted to 200 mL with water and aerated for 3 hours.

Reference substance: 32, 10 and 3.2 mg/L.

Details on test conditions:

DESIGN AND PROCEDURE
Vessels: 250 mL BOD flasks with gas inlet
Water: Dechlorinated drinking water
Temperature: 20 ± 2 °C
Nutrient solution: 16 g Peptone, 11 g Meat extract, 3.0 g Urea, 0.7 g NaCl, 0.4 g CaCl2.2H2O, 0.2 g MgSO4.7H2O, 2.8 g K2HPO4 are dissolved and made up to one litre with dechlorinated drinking water.

Deviations from guideline: Instead of a centrifuged sludge a settled sludge was used. Due to the poor solubility of the test material at test concentrations, no stock solution was prepared: The test material was given directly into the medium. Therefore, a constant factor between the test concentrations could not been achieved.

MEASUREMENTS
Oxygen comsumption per hour in mg/litre with a ORION - Electrode Type 97-08, ORION Microprocessor Ionalizer 901 and plotted on a recorder.

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Key result

Duration:

3 h

Dose descriptor:

other: EC20

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Key result

Duration:

3 h

Dose descriptor:

other: EC80

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Details on results:

Compared to control oxygen consumption rates of  53.1 and 56.5 mg/L/hour, consumptions rates for the test concentrations of 100.5, 43.0, 19.5, 6.5, 3.0, and 1.5 mg/L were 50.5, 50.4, 52.6, 55.4, 54.8, and 58.0 mg oxygen/L/h respectively.

Results with reference substance (positive control):

The calculated EC50 for the reference substance, based on nominal  concentrations, was 12.3 mg/L.  

Reported statistics and error estimates:

The inhibitions were calculated on the basis of the measured time depend oxygen consumption of a Blank and Test solution. The Results ( ECxx Values ) were calculated with linear regression.

Table 1. Rates of inhibition (%) in control and test concentrations.

Sample	Conc (mg/l)	Consumption rate (mg/l/h)	Inhibition (%)
Blank 1	0.0	53.1	3
Blank 2	0.0	56.5	-3
Reference 1	32.0	11.1	80
Reference 2	10.0	31.4	43
Reference 3	3.2	50.0	9
Test conc. 1	100.5	50.5	8
Test conc. 2	43.0	50.4	8
Test conc. 3	19.5	52.6	4
Test conc. 4	6.5	55.4	-1
Test conc. 5	3.0	54.8	0
Test conc. 6	1.5	58.0	6

Validity criteria fulfilled:

yes

Conclusions:

Study met the validity (quality) criteria of the guideline, though it deviated from the method in some minor ways (used settling instead of centrifugation for sludge, and test concentrations were not spaced by an equal factor). Because no significant inhibition of oxygen consumption was found over the test concentrations compared to the controls, resulting EC50 was ≥ 100 mg/L (the highest test concentration). Study provides no direct discussion of whether solubility prevented testing higher concentrations, though this is likely given that elsewhere in the report the poor solubility of the test compound is noted.

Executive summary:

The determination of the inhibitory concentration of the test material on the respiration of aerobic waste water bacteria was performed in accordance with the 87/302/EEC directive.

The test was performed using activated sludge from a sewage treatment plant for a duration of 3 hours in an activated sludge respiration inhibition test.

Under the conditions of this study the LC50 of the test material was greater than 100 mg/L.

Reference 2

Endpoint:

activated sludge respiration inhibition testing

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study conducted on read-across material

Justification for type of information:

Read-across to structurally similar substance Dioctyltin bis (2-ethylhexylmercaptoacetate) (DOTE) (CAS No. 15571-58-1), see attached justification.

Reason / purpose for cross-reference:

read-across source

Key result

Duration:

3 h

Dose descriptor:

other: EC20

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Key result

Duration:

3 h

Dose descriptor:

other: EC80

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Description of key information

Read-across to structurally similar substance

Under the conditions of this study the LC50 of DOTE (CAS No 15571-58-1) was greater than 100 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:

100 mg/L

Additional information

Read-across to structurally similar substance Dioctyltin bis (2-ethylhexylmercaptoacetate) (DOTE) (CAS No. 15571-58-1).

The determination of the inhibitory concentration of the test material on the respiration of aerobic waste water bacteria was performed in accordance with the 87/302/EEC directive.

The test was performed using activated sludge from a sewage treatment plant for a duration of 3 hours in an activated sludge respiration inhibition test

Under the conditions of this study the LC50 of the test material was greater than 100 mg/L.