1-[(4-chlorophenyl)sulfanyl]propan-2-one

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

18 December 2014 - 15 January 2015

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge: aeration tank of Sewage Treatment Plant ”Czajka” , Warsaw. Such prepared sludge was washed in the medium and was placed in laboratory-scale unit where the aerobic conditions were maintained by means of an intense aeration with compressor and aerators.
- Preparation of inoculum for exposure: the concentrated sludge was suspended in mineral medium and it was aerated until application. After complete re-suspension was achieved, a sample was withdrawn just before use for the determination of the dry weight of the suspended solids.
- Pretreatment: inoculum was pre-conditioned to the experimental conditions. Pre-conditioning consisted of aerating activated sludge in mineral medium for 2 days at the test temperature of 22 °C.
- Concentration of sludge: 30 mg/L SS.

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium:
The following stock solutions were prepared using analytical grade reagents:
(a) Monopotassium dihydrogen orthophosphate, KH2PO4 8.50 g
Dipotassium monohydrogen orthophosphate, K2HPO4 21.75 g
Disodium monohydrogen orthophosphate dihydrate Na2HPO4 · 2 H2O 33.40 g
Ammonium chloride, NH4Cl 0.50 g
Dissolve in water and make up to 1 litre The pH of the solution should be 7.4.
(b) Calcium chloride, anhydrous, CaCl2 27.50 g
Dissolve in water and make up to 1 litre
(c) Magnesium sulphate heptahydrate, MgSO4 · 7 H2O 22.50 g
Dissolve in water and make up to 1 litre.
(d) Iron(III) chloride hexahydrate, FeC13 · 6H2O 0.25 g
Dissolve in water and make up to 1 litre.
Mix 10 ml of solution (a) with 800 ml dilution water, add 1 mL of solutions (b) to (d) and make up to 11 with dilution water.
- Test temperature: 22 ± 2°C
- pH: 7.4 ± 0.2
- pH adjusted: no
- Suspended solids concentration: 30 mg/L SS

TEST SYSTEM
- Culturing apparatus: thermo-cabinet WTW TS 606 CZ-G/3-VAR.
- Number of culture flasks/concentration:
Flasks 1, 2, 3: Test suspension containing test item (100 mg/L) and inoculum 30 mg/L SS.
Flasks 13, 14 and 15: Inoculum blank containing only inoculum 30 mg/L SS.
Flask 16, 17 and 18: Procedure control containing reference item (sodium acetate 100 mg/l) ) and inoculum 30 mg/SS.
Flask 4, 5 and 6: Toxicity control: containing test item, reference item at the same concentrations as in the individual solutions and inoculum 30 mg/L SS.
- Measuring equipment:
Consumption of oxygen: closed WTW OxiTop OC 110 respirometer for BOD determination. The consumption of oxygen was determined from the change in pressure in the apparatus. The carbon dioxide, evolved during test item degradation, was absorbed in a solution of potassium hydroxide.

SAMPLING
The oxygen uptake from the readings taken at regular and frequent intervals was calculated, using the methods given by the manufacturer of the equipment. The data were read out every 112 min during the 28 day test (40 320 min that is 360 readings) and were recoded and stored in the measuring heads of the sample bottles. These collected data, using the controller, were infrared read out from the heads and stored in the controller.

CONTROL AND BLANK SYSTEM
- Inoculum blank: 3 flasks containing only inoculum (30 mg/L SS).
- Procedure control: 3 flasks containing reference item (sodium acetate 100 mg/l) and inoculum (30 mg/L SS).
- Toxicity control: 3 flasks containing test item, reference item at the same concentrations as in the individual solutions and inoculum 30 mg/L SS.

Reference substance:

acetic acid, sodium salt

Key result

Parameter:

% degradation (O2 consumption)

Value:

0

Sampling time:

28 d

Details on results:

At the 28th day of the test the aerobic biodegradation of the testing:
The test item attained 0.0% of biodegradation;
In the toxicity test the biodegradation was equal to 17.1%;
The oxygen uptake of the inoculum blank was equal to 44.6 mg/L in 28 days;
The pH values of all flasks were inside the range 6.98-8.60.

Results with reference substance:

At the 28th day of the test the aerobic biodegradation of the testing:
The reference item reached 65.5% of biodegradation. The percentage degradation of the reference substance (69.8%) reached the level for ready biodegradability on 14 day.

The mineral medium solution pH was equal to 7.20.

The preconditioned suspension of inoculum pH was equal to 7.38.

The initial concentration of test item in test flasks was equal to 100 mg/L.

Table 1. pH values of test flasks.

Flask #	1	2	3	13	14	15	16	17	18	4	5	6
	Test item			Control			Reference item			Toxicity test
Initial	7.39	7.40	7.40	7.51	7.47	7.45	7.43	7.42	7.41	7.49	7.48	7.47
Final	6.98	7.02	7.02	7.21	7.11	7.10	8.05	8.27	8.01	8.60	8.28	8.23

No adjustment of pH was conducted.

Table 2. Sample oxygen uptake: biodegradability.

		Time, Days
		3	5	7	9	12	14	16	18	21	23	25	28
Test item O2 uptake, mg/L	a1	0.3	2.0	5.0	4.9	8.9	10.6	12.3	17.0	24.3	28.2	30.6	33.7
	a2	34.6	39.0	33.2	0.0	0.0	0.0	12.4	19.9	0.0	38.3	47.4	24.6
	a3	4.9	5.9	6.5	7.9	12.3	14.4	17.7	20.6	27.3	33.3	37.0	39.5
	am·avg	13.2	15.6	14.9	4.3	7.0	8.3	14.1	19.2	17.2	33.3	38.3	32.6
Blank test O2 uptake. mg/L	b1	17.6	20.4	24.5	27.9	30.9	33.4	34.5	36.6	39.9	40.1	42.2	44.8
	b2	17.5	20.5	23.0	28.4	31.0	30.9	33.2	33.8	36.6	38.3	39.4	42.6
	b3	20.2	22.7	28.3	31.0	34.7	36.6	37.6	39.4	42.2	42.8	45.3	46.5
	bm·avg	18.4	21.2	25.2	29.1	32.2	33.6	35.1	36.6	39.6	40.4	42.3	44.6
Reference item O2uptake. mg/L	w1	33.6	35.2	44.7	48.3	50.6	47.8	47.8	48.8	46.6	47.8	49.5	49.1
	w2	47.5	63.1	72.6	76.1	82.1	82.1	83.2	84.3	83.4	82.9	84.5	84.2
	w3	52.6	67.5	79.7	85.7	91.6	94.0	95.7	99.1	100.5	101.0	103.6	107.2
	wm·avg	50.0	65.3	76.1	80.9	86.9	88.1	89.4	91.7	92.0	91.9	94.1	95.7
Toxicity control O2uptake. mg/L	tox1	38.6	50.2	55.2	59.4	66.4	68.9	72.8	76.3	83.3	84.1	84.4	86.7
	tox2	37.7	45.1	51.0	57.0	62.4	66.9	73.3	79.3	81.6	82.5	83.7	84.3
	tox3	40.4	46.6	54.8	60.1	68.8	73.9	79.4	85.0	97.6	100.3	104.2	110.4
	toxm·avg	38.9	47.3	53.7	58.8	65.9	69.9	75.2	80.2	87.5	88.9	90.8	93.8
Corrected test item O2 uptake, mg/L	(a1-bm)	-18.1	-19.2	-20.2	-24.2	-23.3	-23.0	-22.8	-19.6	-15.2	-12.2	-11.7	-10.9
	(a2-bm)	16.2	17.8	8.0	-29.1	-32.2	-33.6	-22.7	-16.7	-39.6	-2.1	5.1	-20.0
	(a3-bm)	-13.6	-15.3	-18.8	-21.2	-19.9	-19.2	-17.4	-16.0	-12.3	-7.2	-5.3	-5.2
Reference item % degradation (BOD / (ThODr x Cr)) x 100 ThODr = 0.78 mgO2/mg Cr = 100 mg/L	R1(w1)	19.4	18.0	25.0	24.6	23.6	18.1	16.3	15.6	9.0	9.5	9.3	5.7
	R1(w2)	37.2	53.7	60.7	60.3	64.0	62.1	61.7	61.2	56.2	54.5	54.1	50.8
	R1(w3)	43.8	59.4	69.8	72.5	76.1	77.4	77.7	80.1	78.1	77.7	78.6	80.2
	Rtoxavg	40.5	56.6	65.2	66.4	70.0	69.8	69.7	70.6	67.2	66.1	66.4	65.5
Toxicity test % degradation (BOD / (ThODt x Ct + ThODr x Cr)) x 100 ThODr = 0.78 mgO2/mg Cr = 100 mg/L ThODt = 2.70 mgO2/mg Ct = 100 mg/L	Rtox1	7.0	10.1	10.4	10.5	11.9	12.2	13.1	13.8	15.2	15.2	14.6	14.6
	Rtox2	6.7	8.3	8.9	9.7	10.5	11.6	13.3	14.8	14.6	14.6	14.4	13.8
	Rtox3	7.6	8.8	10.3	10.8	12.7	14.0	15.4	16.8	20.2	20.8	21.5	22.8
	Rtoxavg	7.1	9.1	9.9	10.3	11.7	12.6	13.9	15.1	16.7	16.9	16.8	17.1
Test item % degradation (BOD / (ThODt x Ct)) x 100 ThODt = 2.10 mgO2/mg Cr = 100 mg/L	R1(a1)	0	0	0	0	0	0	0	0	0	0	0	0
	R2(a2)	0	0	0	0	0	0	0	0	0	0	0	0
	R3(a2)	0	0	0	0	0	0	0	0	0	0	0	0
	Ravg	0	0	0	0	0	0	0	0	0	0	0	0

The final biodegradation of test item on 28th test day was 0.0%.

In the toxicity test, containing both the test item and a reference item less than 25% of biodegradation (12.6% based on ThOD) occurred in 28 days and the test item probably can be assumed to be inhibitory.

Validity criteria fulfilled:

no

Remarks:

(the test item is inhibitory, biodegradation of 12.6% based on ThOD)

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

At the 28th day of the test the aerobic biodegradation of the testing item was 0%. The substance cannot be deemed to be readily biodegradable.

Executive summary:

The study of ready biodegradability of test substance in aerobic aqueous medium with manometric respirometry method was carried out in accordance with OECD Guideline 301F and EU Method C.4-D, following the Principles of GLP. 30 mg/L of activated sludge were exposed to 100 mg/L of test item during 28 days under aerobic conditions at 22 ºC. The blank tests were run in parallel with only inoculum but without test item. A reference item (sodium acetate) was run in parallel to check the operation of the procedures. The degradation was followed by the determination of oxygen uptake and measurements were taken at sufficiently frequent intervals to allow the identification of the beginning and end of biodegradation. At the 28th day of the test the aerobic biodegradation of the testing item was 0%. The substance is therefore, not readily biodegradable under test conditions. In the toxicity test, containing both the test item and a reference item less than 25% of biodegradation (12.6% based on ThOD) occurred in 28 days and the test item probably can be assumed to be inhibitory.

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH
The analogue substance 7-chloro-3-methyl-1-benzothiophene (SER-4) which shares the aryl functional group chlorophenyl with the substance 1-[(4-chlorophenyl)sulfanyl]propan-2-one (SER-3) also has comparable values for the relevant molecular properties.
See attached the reporting format.

Reason / purpose for cross-reference:

read-across source

Key result

Parameter:

% degradation (O2 consumption)

Value:

0

Sampling time:

28 d

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

Based on the available information for the read-across approach, the target substance is not readily biodegradable.

Description of key information

Read-across from analogue substance.

Key study: Test method according to OECD Guideline 301F. GLP study. At the 28th day of the test the aerobic biodegradation of the testing item was 0%.  The substance cannot be deemed to be readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Type of water:

freshwater

Additional information

Read-across from analogue substance.

Key study: The study of ready biodegradability of test substance in aerobic aqueous medium with manometric respirometry method was carried out in accordance with OECD Guideline 301F and EU Method C.4-D (GLP study). 30 mg/L of activated sludge were exposed to 100 mg/l of test item during 28 days under aerobic conditions at 22 ºC. At the 28th day of the test the aerobic biodegradation of the testing item was 0%. The substance is therefore, not readily biodegradable under test conditions. In the toxicity test, containing both the test item and a reference item less than 25% of biodegradation (12.6% based on ThOD) occurred in 28 days and the test item probably can be assumed to be inhibitory.