(3E)-dec-3-en-2-one

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

10 January 2011 to 14 November 2011

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

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Aerobic activated sludge (micro-organisms from a domestic wastewater treatment plant) was supplied by the sewage works of Darmstadt, Germany.
- Pretreatment: The aerobic activated sludge used for this study was washed by centrifugation and the supernatant liquid phase
was decanted. The solid material was re-suspended in tap water and centrifuged again. This procedure was done three times. The sediment was re-suspended in test water and aerated overnight.
- Concentration of sludge: 1.5 g d.w./L

Duration of test (contact time):

28 d

Initial conc.:

305 mg/L

Based on:

ThOD

Remarks:

105 mg/L corresponding to an oxygen demand of about 305 mg/L (ThODNH4)

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: Analytical grade salts were added to deionised water to prepare the following stock solutions:
a) 8.5 g KH2P04, 21.75 g K2HPO4, 33.4 g Na2HPO4 x 2 H2O, 0.5 g NH4Cl filled up with deionised water to 1000 mL volume
b) 22.5 g MgSO4 x 7 H2O filled up with deionised water to 1000 mL volume
c) 36.4 g CaCl2 x 2 H2O filled up with deionised water to 1000 mL volume
d) 0.25 g FeCl3 x 6 H2O filled up with deionised water to 1000 mL volume
In order to avoid precipitation of iron hydroxide in the stock solution d) after storage and before use, one drop of concentrated HCl per litre was added.
10 mL of stock solution a) and 1 mL of the stock solutions b) to d) were combined and filled up to a final volume of 1000 mL with deionised water.


- Additional substrate:
- Solubilising agent (type and concentration if used):
- Test temperature: 21-22°C
- pH: 7.5 (measured at the start of the test), 7.3-7.7 (measured at the end of the test)
- pH adjusted: no
- Suspended solids concentration: 1.5 g d.w./L (final concentration: 21 g/L)
- Continuous darkness: yes

TEST SYSTEM
Manometric Test System with test flasks containing a volume of approximately 500 mL. The pressure decrease in the reaction vessels was measured over complete experimental phase of 28 days using the BSB Sensomat system, Aqualytic Dortmund. The test flasks were closed gas-tight by a measuring head.
The amounts of test item and reference item were directly weighed into the test flasks. No emulsifiers or solvents were used, but the solutions were dispersed by stirring to achieve a homogeneous solution of the test item. The closed test flasks were incubated in a climatised room
under continuous stirring. The consumption of oxygen was determined by measuring the change of pressure in the flasks. Evolved carbon dioxide was absorbed in an aqueous solution (45%) of potassium hydroxide.
Temperature was measured each working day in the climatised room.
pH-values were measured in control, procedure control and a separately prepared test flask with test item at test start (to prevent loss of test item in the test flasks) and in all flasks at the end ofthe test using a pH-electrode WTW pH 340i.

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes, 2 replicates
- Abiotic sterile control: Yes, 1 replicate
- Toxicity control: Yes, 1 replicate
- Other: Reference: 2 replicates

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (O2 consumption)

Value:

60

Sampling time:

28 d

Details on results:

The mean percentage biodegradation at the end of the 28-day exposure period was 60% (ThODNH4). The 10 day window was not passed. The results are represented in Tables 2 (see "Any other information on results incl. tables") and Figure 1.

Results with reference substance:

The reference item sodium benzoate was sufficiently degraded to 93% after 14 days and to 93% after 28 days of incubation. Therefore, percentage biodegradation of the reference item confirms the suitability of the used aerobic activated sludge inoculum.

Table 2. Percentage Biodegradation of Test Item, of Sodium Benzoate and of the Toxicity Control based on ThODNH4

Time (days)	Percentage Biodegradation
	3-Decene-2-one^1		Sodium Benzoate^2	Toxicity control^1,2
	Flask 1 [%]	Flask 2 [%]	Flask 5 [%]	Flask 7 [%]
1	0	0	32	6
2	-2	-2	41	21
3	12	17	54	25
4	20	23	64	25
5	26	29	80	26
6	28	31	84	27
7	32	34	87	28
8	35	38	90	29
9	38	41	90	30
10	41	42	92	31
11	42	43	90	32
12	43	44	93	33
13	45	46	93	34
14	45	46	93	34
15	46	49	93	36
16	46	49	93	36
17	50	51	93	38
18	50	51	93	39
19	53	51	93	41
20	53	51	93	42
21	55	53	93	42
22	55	53	93	42
23	56	54	93	44
24	56	54	93	44
25	58	56	93	45
26	58	56	93	45
27	58	57	93	45
28	60	59	93	46
^1ThODNH4 of 3-Decene-2-one: 2.904 mg O2/mg ^2ThODNH4 of sodium benzoate: 1.666 mg O2/mg

Conclusions:

- Sodium Benzoate: The reference item sodium benzoate was sufficiently degraded to 93% after 14 days and also to 93% after 28 days of incubation. Therefore, percentage biodegradation of the reference item confirms the suitability of the used aerobic activated sludge inoculum.

- Toxicity control: In the toxicity control containing both the test item and reference 34% biodegradation was noted within 14 days and 46% biodegradation was determined after 28 days of incubation. According to the test guidelines the test item can be assumed to be not inhibitory on the aerobic activated sludge micro organisms because degradation was >25% within 14 days. Nevertheless, the toxicity control shows that the test item has an inhibitory effect on the biotic degradation.

- Validity Criteria of the Study:

- Inoculum Control: The oxygen demand of the inoculum control (medium and inoculum) was 30 mg O2/L and thus not greater than 60 mg O2/L within 28 days as required by the test guideline.

- pH-value: The pH-value of the test item flasks at the end of the test was 7.5 — 7.6 and therefore within the range of pH 6.0 to 8.5 as required by the test guideline.

- Reference Item: The percentage degradation of the reference item should reach the level for ready biodegradability (> 60%) within l4 days as required by the test guideline. The reference item sodium benzoate was degraded to more than 60% after 4 days of incubation.

- Test Item: The difference of duplicate values for the degradation of the test item at the plateau and at the end of the test was less than 20%. The difference on day 28 was zero. The validity criterion was fulfilled.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable, but failing 10-day window

Conclusions:

The degradation of the test item within 28 days was 60 % of ThOD. The 10 day window was not passed. Therefore, (3E)-dec-3-ne-2-one is considered to be readily biodegradable, but failing the 10 day window. The degradation of the toxicity control after 14 days was >25%. The test item had no inhibitory effect on the inoculum according to the criterion of the guideline. No abiotic degradation could be detected. The test is valid according to OECD 301 F (July 1992).

Executive summary:

A manometric respirometry test according to OECD 301 F (July 1992) was conducted in order to investigate the ready biodegradability of (3E)-dec-3-ne-2-one. The biodegradation of (3E)-dec-3-ne-2-one was studied in reconstituted water inoculated with activated sludge from a domestic wastewater treatment plant with a concentration corresponding to 1.5 g dry solids per litre. The manometric respirometry test determines the ready biodegradability of test items following their oxygen consumption in closed flasks at a constant temperature (±1 °C) in a range of 18–22°C. The consumption of oxygen is determined by measuring the negative pressure in the flasks after absorption of the evolved carbon dioxide in potassium hydroxide. A solution or suspension of the test item in a mineral medium, corresponding to 105 mg/L test item giving at least 305 mg/L of theoretical oxygen demand (ThOD), is inoculated with activated sludge for 28 days. The amount of oxygen taken up by the microbial population during the biodegradation of the test item (corrected for uptake by blank inoculum, run in parallel) is expressed as a percentage of the ThOD. The pass level for ready biodegradability is 60 % of ThOD and must be reached within a 10-d window. The 10-d window begins when the degree of biodegradation reaches 10 %. The test method is suitable for water soluble and non-soluble test items that are non-volatile and not toxic under the test conditions.

The mean degradation rate of the test item was 60 % at the end of 28 days of exposure. The 10-day window was not passed. Therefore, (3E)-dec-3-ne-2-one is considered to be readily biodegradable, but failing the 10-day window based on ThOD.

According to the test guideline, the test item can be assumed to be not inhibitory to the aerobic activated sludge microorganisms because degradation was >25% within 14 days. Though a degradation of 34 % in the toxicity control at day 14 compared to a degradation of 93 % at day 14 in the positive control indicates that the test item inhibited the activity of the microorganisms.

The test is valid according to OECD Test Guideline 301F (July 1992):

• The oxygen uptake of the inoculum blank was 30 mg O2/L and did not exceed 60 mg O2/L in 28 days.

• The pH value in the test and blank bottles was 7.5–7.6.

• The difference of extremes of replicate values was less than 20 %.

• The biodegradation of the reference item reached the pass level of 60 % ThOD by day 28.

• The degradation extent in the toxicity control was above 25 %, i.e. 34 % in 14 days based on ThOD.

• The degradation extent in the positive control was 93 % after 14 days based on ThOD.

Description of key information

A manometric respirometry test according to OECD 301 F (July 1992) was conducted in order to investigate the ready biodegradability of (3E)-dec-3-en-2-one.

The degradation of the test item within 28 days was 60 % of ThOD. The 10 day window was not passed. Therefore, (3E)-dec-3-en-2-one is

considered to be readily biodegradable, but failing the 10 day window.

The degradation of the toxicity control after 14 days was > 25 %. The test item had no inhibitory effect on the inoculum according to the criterion of the guideline. No abiotic degradation could be detected.

The test is valid according to OECD 301 F (July 1992).

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable but failing 10-day window

Type of water:

freshwater

Additional information

105 mg test item/L were applied in the OECD 301 F test. Although the test is valid with a degradation of 34 % in 14 days in the toxicity control, the result also shows an inhibitory effect of the substance on the microorganisms. The positive control without test item was degraded to 93 % after 14 days based on ThOD.