Ethanone, 1-(4-methoxyphenyl)-2-[(3-methoxyphenyl)thio]-

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Jul 2006 to Feb 2008

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2008

Report date:

2008

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

-

EC Number:

469-300-0

EC Name:

-

Cas Number:

63675-73-0

Molecular formula:

Hill Empirical Formula: C16H16O3S CAS Empirical Formula: C16H16O3S

IUPAC Name:

1-(4-methoxyphenyl)-2-[(3-methoxyphenyl)sulfanyl]ethan-1-one

Test material form:

solid: particulate/powder

Details on test material:

Lot no: 151105Purity - 101.39%

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

A sample of activated sludge was collected from one of the return lines at Burley Menston sewage treatment works (West Yorkshire, UK), a treatment works with a waste-water catchment that is predominantly domestic. On arrival at the laboratory, the sample was aerated by means of a compressed air supply delivered through a diffuser block.

Duration of test (contact time):

56 d

Initial test substance concentration

Initial conc.:

15 mg/L

Based on:

IC (inorganic carbon)

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

Four treatment groups were established:Controlinoculated mineral salts mediumReferenceinoculated mineral salts medium plus sodium benzoate at 15 mgC/LTestinoculated mineral salts medium plus test substance at 15 mgC/LToxicity controlinoculated mineral salts medium plus both the test and reference substances each at 15 mgC/L.The purpose of the toxicity control was to assess the biodegradation of the reference substance in the presence of the test substance.Duplicate vessels were established in the test, reference and control groups. A single vessel was established for the toxicity control.

Reference substance

Reference substance:

benzoic acid, sodium salt

Results and discussion

% Degradation

% Degradation 1

Parameter:

% degradation (CO2 evolution)

Value:

0

Sampling time:

1 d

% Degradation 2

Parameter:

% degradation (CO2 evolution)

Value:

0

Sampling time:

2 d

% Degradation 3

Parameter:

% degradation (CO2 evolution)

Value:

0

Sampling time:

3 d

% Degradation 4

Parameter:

% degradation (CO2 evolution)

Value:

0

Sampling time:

5 d

% Degradation 5

Parameter:

% degradation (CO2 evolution)

Value:

0

Sampling time:

8 d

% Degradation 6

Parameter:

% degradation (CO2 evolution)

Value:

0

Sampling time:

11 d

% Degradation 7

Parameter:

% degradation (CO2 evolution)

Value:

0

Sampling time:

14 d

% Degradation 8

Parameter:

% degradation (CO2 evolution)

Value:

0

Sampling time:

18 d

% Degradation 9

Parameter:

% degradation (CO2 evolution)

Value:

0

Sampling time:

22 d

% Degradation 10

Parameter:

% degradation (CO2 evolution)

Value:

0

Sampling time:

26 d

% Degradation 11

Parameter:

% degradation (CO2 evolution)

Value:

1

Sampling time:

27 d

% Degradation 12

Parameter:

% degradation (CO2 evolution)

Value:

6

Sampling time:

28 d

% Degradation 13

Parameter:

% degradation (CO2 evolution)

Value:

16

Sampling time:

32 d

% Degradation 14

Parameter:

% degradation (CO2 evolution)

Value:

21

Sampling time:

35 d

% Degradation 15

Parameter:

% degradation (CO2 evolution)

Value:

26

Sampling time:

39 d

% Degradation 16

Parameter:

% degradation (CO2 evolution)

Value:

28

Sampling time:

42 d

% Degradation 17

Parameter:

% degradation (CO2 evolution)

Value:

30

Sampling time:

46 d

% Degradation 18

Parameter:

% degradation (CO2 evolution)

Value:

31

Sampling time:

49 d

% Degradation 19

Parameter:

% degradation (CO2 evolution)

Value:

32

Sampling time:

53 d

% Degradation 20

Parameter:

% degradation (CO2 evolution)

Value:

33

Sampling time:

56 d

BOD5 / COD results

Results with reference substance:

See below for results of test substance compared to reference and toxicity control

Any other information on results incl. tables

Overall results

	% Biodegradation
Days	1	2	3	5	8	11	14	18	22	26
Test *	0	0	0	0	0	0	0	0	0	0
Reference**	16	34	43	53	62	68	74	79	84	87
Toxicity Control *** (% total ThCO2)	10	20	25	28	31	32	34	35	38	44
Toxicity Control *** (% sodium benzoate ThCO2)	19	40	49	57	61	64	67	71	76	88
	% Biodegradability
Day	27	28	32	35	39	42	46	49	53	56
Test*	1	6	16	21	26	28	30	31	32	33
Reference**	88	89	90	91	92	92	93	94	94	96
Toxicity control*** (% total ThCO2)	48	50	54	56	59	61	62	63	64	66
Toxicity control *** (% sodium benzoate ThCO2)	95	100	107	113	118	121	124	126	128	133

* = Beta ketosulfide (15 mgC/L)

** = Sodium Benzoate (15mgC/L)

***= Beta Ketosulfide (15 mgC/L) plus Sodium Benzoate (15mgC/L)

Beta ketosulfide

The test substance showed no evident of biodegradation until Day 28 of the test, when a sharp increase in the rate of CO2 evolution from the test vessels was noted. The duration of the test was extended beyond 28 days. Biodegradation of the test substance was considered to have attained a plateau by Day 56. The final mean % degradation for vessels containing Beta Ketosulfide was 33%. To be considered to be readily biodegradable,a test substance must achieve 60% biodegradation by the end of the test. Additionally, the rate of biodegradation must be sufficient to reach 60% biodegradation within ten days of reaching 10%. Consequently, Beta Ketosulfide cannot be considered to be readily biodegradable.

Sodium benzoate

Rapid biodegradation commenced immediately and declined to a more gradual rate after approximately 8 days. Biodegradation had achieved 60% in both vessels by day 8. Mean biodegradation in the reference vessels was 73% on day 14, 89% on day 28 and 96% at the end of the test.

Toxicity control

Vigorous CO2 production began immediately in the toxicity control. The rate of CO2 production generally followed that observed in the two reference vessels containing sodium bezoate alone but at a slightly reduced absolute amount. The onset of biodegradation of the test substance in the vessel is evident from day 28 onwards where a sharp increase in CO2 evolution is noted as in the test vessels.

Biodegradation of sodium benzoate in the vessel, based on the theoretical yield of the reference and test substances, achieved 34% on Day  14 of the test. The calculated result for biodegradation in this vessel was 66% on Day 56. Biodegradation of sodium benzoate in the vessel,  based on the teoretical  yield of the reference substance alone, achieved 67% on Day 14 of the test. The calculated result for biodegradation in this vessel was  100% on Day 28 and exceeded  100% thereafter. This  is because  the calculation is based upon the maximwn theoretical amount of carbon dioxide evolution possible through biodegradation of the reference substance alone. Consequently, the calculation does not make allowance for the contribution to the carbon dioxide evolution in this vessel resulting from biodegradation of the test substance. The absence  of any significant suppression  ofbiodegradation when compared  to the

performance of sodium  benzoate alone demonstrates that the Beta Ketosulfide present was not toxic to the test system. This is further supported by the level of biodegradation of the test substance  observed.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

Beta Ketosulfide cannot be considered to be readily biodegradable. Beta Ketosulfide is considered to have shown significant evidence of mineralisation over 56 days.

Executive summary:

The study was carried out in accordance with the method described in Annex V of EU Directive 67/548/ EEC: Part C4: Biodegradation: determination of 'ready' biodegradability, method C - Carbon Dioxide Evolution test.The method is identical to the1992 revision of OECD Guideline 301B and that in section (m) of US EPA OPPTS method 835.3110. The test was extended beyond the standard 28 day incubation period on the basis of the results obtained.

After a lag period of 28days, biodegradation of Beta Ketosulfide attained a plateau by Day 56.The final mean % biodegradation value for vessels containing Beta Ketosulfide was 33%.

 

As 60% biodegradation of Beta Ketosulfide was not achieved by the end of the test,Beta ketosulfide cannot be considered to be readily biodegradable