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Environmental fate & pathways

Biodegradation in water: screening tests

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Administrative data

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
9th November 2016 to 7th December 2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
Guideline study to GLP standards with no deviations

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2017
Report date:
2017

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Deviations:
no
Principles of method if other than guideline:
Not applicable
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Chemical structure
Reference substance name:
5-chloropentan-2-one
EC Number:
227-565-8
EC Name:
5-chloropentan-2-one
Cas Number:
5891-21-4
Molecular formula:
C5H9ClO
IUPAC Name:
5-chloropentan-2-one
Test material form:
liquid
Remarks:
dark brown
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch number of test material:
5-Chloropentan-2-one (CAS-No.: 5891-21-4) Batch number 6U01818
- Purity test date:
06/09/2016
- Purity: 95.9%

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material:
At 20 ± 5 °C, in the dark

Study design

Oxygen conditions:
aerobic/anaerobic
Inoculum or test system:
activated sludge, domestic (adaptation not specified)
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Rossdorf, Germany
- Method of cultivation: Aerobic activated sludge, microorganisms from a domestic waste water treatment plant was supplied by the sewage treatment plant
- Pretreatment: coarse particles were removed by settling for a short period (30 minutes) and then the upper layer decanted. The resulting activated sludge was aerated overnight until use.
- Concentration of sludge: 3.5 g/l
Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
103.1 mg/L
Based on:
ThOD
Remarks:
NH4
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: standard mineral medium as per guideline
- Test temperature: 22°C ± 1°C
- pH: 7.6 (measured at the start of the test); 7.1 to 7.7 (measured at the end of the test)
- pH adjusted: no
- Continuous darkness: yes


TEST SYSTEM
- Culturing apparatus: test flasks containing a volume of approximately 500 ml
- Number of culture flasks/concentration: 2
- Measuring equipment: BSB/BOD-Sensor-System, Aqualytic Dortmund, Germany
- Test performed in open system: No, according to test guidelines
- Details of trap for CO2 and volatile organics if used: Potassium hydroxide solution (45%) was used for trapping the produced carbon dioxide.

SAMPLING
- Sampling frequency: Daily
- Sampling method: The change of pressure in the test flasks was measured by means of a manometric method (BSB/BOD-Sensor-System, Aqualytic Dortmund, Germany) each day.

CONTROL AND BLANK SYSTEM
- Inoculum blank: One flask
- Abiotic sterile control: One flask
- Toxicity control: One flask
- Other: Procedure control: One flask
Reference substance
Reference substance:
benzoic acid, sodium salt

Results and discussion

Preliminary study:
None
Test performance:
Test criteria were all validated
% Degradationopen allclose all
Key result
Parameter:
% degradation (O2 consumption)
Value:
76
Sampling time:
28 d
Parameter:
% degradation (O2 consumption)
Value:
66
Sampling time:
13 d
Parameter:
% degradation (O2 consumption)
Value:
23
Sampling time:
3 d
Details on results:
5-Chloropentan-2-one did reach a mean biodegradation of at least 10% at day 3, when the degradation was 23%. At the end of the 10-day window at day 13, the degradation was 66%. At the end of the test, the
degradation of 5-Chloropentan-2-one was 76% (ThODNH4).

In the toxicity control containing both, the test item and the reference item sodium benzoate, the biodegradation based on ThODNH4 was 61% after 14 days and 71% biodegradation after 28 days of incubation. According to the test guidelines the test item can be assumed to be not inhibitory to the aerobic activated sludge microorganisms because degradation was >25% within 14 days.

The oxygen demand in the abiotic control was 0 mg/L during the test duration.

BOD5 / COD results

Results with reference substance:
The reference item sodium benzoate was sufficiently degraded to 89% after 14 days and to 97% after 28 days of incubation. The percentage biodegradation of the reference item confirms the suitability of the used aerobic activated sludge inoculum.

Any other information on results incl. tables

Cumulative Biochemical Oxygen Demand (mg O2/L) in Test Flasks during the Test Period

of 28 Days

Time (days) Flask No.
1 2 3 4 5 6 7
1 0 0 0 0 55 0 55
2 0 5 5 0 80 0 75
3 45 45 5 5 95 0 95
4 70 65 10 5 120 0 130
5 80 75 10 5 130 0 135
6 95 85 10 5 135 0 145
7 105 95 10 5 145 0 155
8 115 105 10 5 150 0 165
9 120 110 10 5 150 0 175
10 125 110 10 5 155 0 185
11 125 115 10 10 155 0 195
12 130 120 10 10 160 0 210
13 130 125 10 10 160 0 220
14 135 130 10 10 160 0 225
15 135 130 10 10 165 0 235
16 135 135 10 10 165 0 245
17 140 135 10 10 165 0 250
18 140 140 10 10 165 0 255
19 140 140 10 10 165 0 255
20 145 140 10 10 165 0 255
21 145 145 10 10 170 0 260
22 145 145 10 10 170 0 260
23 145 145 10 10 170 0 260
24 145 145 10 10 170 0 260
25 145 145 10 10 175 0 260
26 145 145 10 10 175 0 260
27 145 145 10 10 175 0 260
28 145 145 10 10 175 0 260

Flasks 1 and 2: 5-Chloropentan-2-one

Flasks 3 and 4: inoculum control

Flask 5: reference (procedure control)

Flask 6: abiotic control

Flask 7: toxicity control

Percentage Biodegradation of the Test Item, of the Toxicity Control and of Sodium Benzoate

based on ThODNH4

Time (days) Percentage Biodegradation 1
5-Chloropentan-2-one 1 Sodium Benzoate 2 Toxicity control 1,2
Flask 1 [%] Flask 2 [%] Flask 5 [%] Flask 7 [%]
1 0 0 32 16
2 0 1 46 21
3 22 23 53 26
4 35 33 66 35
5 40 38 72 36
6 49 44 75 39
7 54 50 81 42
8 60 55 84 45
9 63 58 84 48
10 65 58 87 50
11 64 60 86 53
12 67 62 89 57
13 67 65 89 60
14 70 68 89 61
15 70 68 92 64
16 70 71 92 67
17 72 71 92 68
18 72 74 92 70
19 72 74 92 70
20 75 74 92 70
21 75 77 94 71
22 75 77 94 71
23 75 77 94 71
24 75 77 94 71
25 75 77 97 71
26 75 77 97 71
27 75 77 97 71
28 75 77 97 71

1 ThODNH4 of 5-Chloropentan-2-one: 1.725 mg O2/mg test item

2 ThODNH4 of sodium benzoate: 1.666 mg O2/mg reference item

pH-Values at the End of the Test

Flask No. Treatment pH-value
1 5-Chloropentan-2-one 7.1
2 5-Chloropentan-2-one 7.1
3 Inoculum control 7.6
4 Inoculum control 7.6
5 Reference item (procedure control) 7.7

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
The reliable OECD 301F Guideline study on ready biodegradability reported a degradation rate of 5-Chloropentan-2-one of 60% within the 10-day window and 76% after 28 days. Therefore, 5-Chloropentan-2-one is considered to be readily biodegradable.
Executive summary:

The reliable OECD 301F Guidleine study on ready biodegradability was undertaken to GLP standards. Inoculum used was activated domestic sludge. Test conditions included test material, inoculum control, procedural control (sodium benzoate), abiotic control (CuSO4) and toxicity control (test material + sodium benzoate). Oxygen degradation was measured daily in sealed flasks using a BOD sensor.

The following results were determined:

5-Chloropentan-2-one reached a mean biodegradation of at least 10% at day 3, when the degradation was 23%. At the end of the 10-day window at day 13, the degradation was 66%. At the end of the test, the degradation of 5-Chloropentan-2-one was 76% (ThODNH4). Therefore, 5-Chloropentan-2-one is considered to be readily biodegradable based on ThODNH4.

Biodegradation of Sodium Benzoate: The reference item sodium benzoate was sufficiently degraded to 89% after 14 days and to 97% after 28 days of incubation, thus confirming the suitability of the aerobic activated sludge inoculum used.

Biodegradation of the Toxicity Control: In the toxicity control containing both the test item and the reference item sodium benzoate, 61% biodegradation was noted within 14 days and 71% biodegradation after 28 days of incubation (based on ThODNH4). According to the test guidelines, the test item can be assumed to be not inhibitory to the aerobic activated sludge microorganisms because degradation was >25% within 14 days.

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