Tin sulphide

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:

2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

GLP and guideline compliant study with good documentation,

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Qualifier:

according to guideline

Guideline:

EU Method C.11 (Biodegradation: Activated Sludge Respiration Inhibition Test)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: 3 litre of deionized water were spiked with weighed amount of the test item equal to 300 mg. Sample (on flask) was incubated at temperature 20.0 – 22ºC for 24 h with constant agitation and stirring. This process was on magnetic stirrer with magnet for mixing. Sample was filtered through 0.45 μm nitrocellulose membrane. According to chemical analysis of solubility in deionized water the concentration of test material in such prepared stock solution was equal to 0.024 mg/L.

Test organisms (species):

activated sludge

Details on inoculum:

- Origin: biological sewage refinery in Pszczyna. Activated sludge was immediately transported to laboratory in a period of time shorter than 60 minutes.
- Preparation of inoculum for exposure: After transport the decantation of activated sludge was made for at least 60 minutes followed by draining of supernatant. The remaining sludge was rinsed with tap water for three times. After the last rinsing, the sediment was carefully poured from the vessel to two tall beakers with a volume of 5 L and 50 ml of synthetic sewage feed were added per 1 L of activated sludge. Activated sludge was intensively aerated in temperature of 20°C to keep circulation of sludge suspended solids in the volume of the vessel. The compressed air came from aquarius aeration pump and were inflated through a glass frit.
- Initial biomass concentration: 1.6 g dw/L

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Hardness:

not applicable

Test temperature:

20.0 - 22.0°C

pH:

6.78

Dissolved oxygen:

not applicable

Salinity:

not applicable

Nominal and measured concentrations:

No analytical measurements were performed during the test

Details on test conditions:

TEST SYSTEM
- Test vessel: Beakers, 0.6 L
- Biomass loading rate: 1.6 g dw/L

TEST CONCENTRATIONS:
- Spacing factor for test concentrations: 1.1
- Range finding study
- Test concentrations: 11, 10, 9.1, 8.3, 7.5 µg/L (nominal concentrations calculated based on the measured Tin Sulfide solubility (20 µg/L, with regard to a pretest that is documented in the study plan)) + control

In an additional experiment, the test item directly weighted into test vessels. Test item concentrations were 1000, 500, 250, 125, 62.5 mg/L (nominal) + control

Reference substance (positive control):

yes

Remarks:

3.5-dichlorophenol

Duration:

3 h

Dose descriptor:

other: EC20

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Remarks on result:

other: 2. Experiment, direct weight

Results with reference substance (positive control):

1. Experiment: EC50 = 12.3 mg/L
2. Experiment: EC50 = 7.3 mg/L

Percentage of activated sludge respiration inhibition for tested material (1st test):

Concentration [µg/L]	Inhibition [%]
11	-0.80
10	-6.63
9.1	-7.16
8.3	-7.69
7.5	-8.22

 

Percentage of activated sludge respiration inhibition for tested material (additional test, directly weighing in):

Concentration [mg/L]	Inhibition [%]
1000	14.98
500	9.41
250	3.14
125	12.20
62.5	9.76

 

Validity criteria fulfilled:

yes

Conclusions:

In a test on respiration inhibition of activated sludge according to OECD 209, no effects were observed at a nominal concentration of 11 µg/L. In an additional experiment, no effects were observed at concentrations up to 1000 mg/L with directly weighing in.

Executive summary:

In a test on respiration inhibition of activated sludge according to OECD 209, no effects were observed at a nominal concentration of 11 µg/L. In an additional experiment, no effects were observed at concentrations up to 1000 mg/L with directly weighing in.

Reference 2

Endpoint:

activated sludge respiration inhibition testing

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 209 (Activated Sludge, Respiration Inhibition Test (Carbon and Ammonium Oxidation))

Version / remarks:

OECD.OECD Guidelines for Testing of Chemicals, 209 Activated Sludge, Respiration Inhibition Test（Carbon and Ammonium Oxidation）[S]. Paris: OECD. Adopted 22th July, 2010.

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method:
Since the test substance is insoluble in the water under the test condition, the method of directly addition was adopted for the study.
Each 5 mg of the test substance was respectively weighed into flasks FT1 and F1, resulting in a final concentration of 10 mg a.i./L in the test solutions.
Each 52 mg of the test substance was respectively weighed into flasks FT2 and F2, resulting in a final concentration of 100 mg a.i./L in the test solutions.
Each 518 mg of the test substance was respectively weighed into flasks FT3-5, FA1-3 and F3, resulting in a final concentration of 1001 mg a.i./L in the test solutions.


- Controls: blank control + reference substance controls as described in the guidance document

- Chemical name of vehicle (organic solvent, emulsifier or dispersant): none

- Test concentration separation factor: 10

- Evidence of undissolved material (e.g. precipitate, surface film, etc.): test item is insoluble

Test organisms (species):

activated sludge

Details on inoculum:

Near the exit of the aeration tank from Datansha Water Purification Plant of Guangzhou
Address No.3 Tanwei Street, Middle Pearl River Bridge, Guangzhou
- Laboratory culture:

- Name and location of sewage treatment plant where inoculum was collected: Near the exit of the aeration tank from Datansha Water Purification Plant of Guangzhou Address: No.3 Tanwei Street, Middle Pearl River Bridge, Guangzhou

- Method of cultivation:
After collection, any coarse particles and impurities were removed from the sludge by sieving of a strainer with the aperture of 80 meshes, then washed and re-suspended in chlorine free tap water. This was cultivated for one day by 50 mL of synthetic sewage feed per litre of activated sludge was fed and aerated under the test temperature of 20°C±2°C. Before the study, the solids dry weight of the activated sludge suspension was determined, followed by adjusting the initial concentration of the suspended solids dry weight to 3.0 g/L with the chlorine free tap water, and adjusting its pH value to 7.29 before being used.

- Preparation of inoculum for exposure: see above

- Pretreatment: see above

- Initial biomass concentration: 3.0 g dw /L

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test temperature:

19.4°C - 21.7°C during the sludge sensitivity test and 20.0°C - 22.0°C during the range-finding test

pH:

the pH values of test mixtures at the start and the end of the test were in the range of 7.57 - 7.59 and 7.82 - 8.12, the pH values of abiotic control at the start were in the range of 7.25 - 7.27, and the end of the test were in the range of 7.20 - 7.21.

Dissolved oxygen:

initial DO: 8.72 to 8.99
initial DO at measurement for calculation: 5.23 to 8.47
terminal DO after meaurement: 2.05 to 7.42
(the values include all controls including the positive controls and the test solutions)

Nominal and measured concentrations:

10, 100, 1001 1001, 1001 mg test item /L
Blank controls 1 - 4 (0 mg test item/L)
5 reference substance test groups (0 mg test item/L)

Details on test conditions:

TEST SYSTEM
- Test vessel: 500 mL vessels with ventilating pipes;
- Typ: open
- Material, size, headspace, fill volume: 500 mL
- Aeration: yes
- No. of vessels per concentration (replicates): 1 for 10 and 100 mg/L 3 for 1001 mg/L
- No. of vessels per control (replicates): 4
- No. of vessels per vehicle control (replicates): not applicable
- No. of vessels per abiotic control (replicates): 3
- Sludge concentration (weight of dry solids per volume): 1.5 g/L
- Nutrients provided for bacteria: Synthetic sewage feed
- Nitrification inhibitor used (delete if not applicable): N-allylthiourea
- Biomass loading rate: 1.5 g/L
TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: dechlorinated tap water

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: not applicable
- Light intensity: not reported
- Details on termination of incubation: measurement of DO decline
EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : rate of DO consumption EC50 and NOEC
TEST CONCENTRATIONS
- Spacing factor for test concentrations: 10
- Justification for using fewer concentrations than requested by guideline: highest test concentration tested in triplicate and no effects were observed. Hence, only the range finding test was performed.
- Range finding study: yes
- Test concentrations: 10, 100, 1001 mg/L
- Results used to determine the conditions for the definitive study: no defiinitive test needed.

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol, Allyl thiourea (ATU)

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 1 001 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Key result

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

>= 1 001 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Results with reference substance (positive control):

- Results with reference substance valid? yes

Validity criteria fulfilled:

yes

Conclusions:

The 3h-EC50 of the test substance for the total oxygen uptake was higher than 1001 mg a.i./L, and NOEC was 1001 mg a.i./L.

Executive summary:

In the K1-study from Deng Guirong (2021), the effect of tin sulfide on the respiration of sewage sludge was investigated according to OECD 209. The 3h-EC₅₀ of the test substance for the total oxygen uptake was higher than 1001 mg a.i./L, and NOEC was 1001 mg a.i./L, the highest test concentration.

The results of that study are considered robust and reliable for the risk assessment of the registered substance.

Description of key information

Tin sulfide causes no adverse effects on respiration of microorganisms up to 1000 mg/L which is above the limit of water solubility. 

Key value for chemical safety assessment

EC50 for microorganisms:

1 000 mg/L

EC10 or NOEC for microorganisms:

1 000 mg/L

Additional information

Tin sulfide, at used concentrations, caused no inhibition of respiration of activated sludge. Based on the results obtained during additional test EC50 is above the highest nominal concentration – 1000 mg/L. The concnetration of this suspension was above water solubility limit.