Octane-1,2-diol

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: According to international guideline(s), GLP-compliant, performed in recognized contract research organization, no restrictions, fully adequate for assessment.

Qualifier:

according to guideline

Guideline:

EU Method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 D (Ready Biodegradability: Closed Bottle 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 activated sludge: municipal activated sludge plant of Pforzheim/Germany
- Method of cultivation / Preparation of inoculum for exposure: The effluent was kept under aerobic conditions in the period between sampling and application. The inoculum was filtered through a coarse filter (Macherey & Nagel), the first 200 mL being discarded, and was shaken one hour for starvation. The initial number of micro organisms in the test vessels was determined separately for each study group (blank, test item, reference and toxicity control).

Duration of test (contact time):

28 d

Initial conc.:

2 mg/L

Based on:

test mat.

Initial conc.:

5 mg/L

Based on:

ThOD/L

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: mineral salts medium according to guideline, prepared from individual stock solutions using ultra pure grade water.
- Test temperature: 20 ± 2 °C
- pH: not indicated
- Aeration of dilution water: strong aeration for at least 60 minutes
- Suspended solids concentration: Test solutions were inoculated with 0.02 mL of inoculum per litre of final volume. The cell numbers for each test group were determined prior to the distribution into the test vessels: inoculum blank: 1765 cells/mL, test item: 1390 cells/mL, reference: 1000 cells/mL, toxicity control: 1405 cells/mL
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: BOD flasks with ground-in-glass stoppers
- Number of culture flasks/concentration and sampling date: 3
- Measuring equipment: WTW Microprocessor Oximeter OXI 340 with calibrated electrode

SAMPLING
- Sampling frequency: Day 0, 7, 14, 21 and 28
- Sampling method: Three bottles from each study group were removed for measurement of the oxygen content. Each assay was measured twice.

CONTROL AND BLANK SYSTEM
- Inoculum blank: inoculated mineral salts medium (MSM)
- Reference: inoculated MSM + 2 mg sodium benzoate/L (corresponding to 3.3 mg O2/L)
- Toxicity control: inoculated MSM + 1 mg test material/L + 1 mg sodium benzoate/L (corresponding to 4.2 mg O2/L)

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (O2 consumption)

Value:

75

Sampling time:

28 d

Remarks on result:

other: mean of three replicates

Details on results:

Mean oxygen consumption in biotic mixtures containing the test material was equivalent to 10% of the ThOD value after approximately 8 days, 61% after 14days and 75% at the end of the test (Day 28). Thus, the test material was ready biodegradable (Table 1).

The degradation rate of the toxicity control (sodium benzoate + test item) was 73% after 14 days indicating that the test substance was not inhibitory to the microbial inoculum (Table 1).

Results with reference substance:

The reference substance sodium benzoate had achieved 66% of the ThOD after 7 days of incubation and 87% by Day 28 (Table 1).

Table 1 Biodegradation in the Test Flasks

	Percentage biodegradation
Time (days)	Test item			Procedure control			Toxicity control
	Replicate No.			Replicate No.			Replicate No.
	1	2	3	1	2	3	1	2	3
7	11.1	0.4	-2	64.1	68.9	64.1	56.8	54.5	57.3
14	66.8	56.0	59.6	67.7	65.9	65.9	75.5	67.8	74.5
21	79.1	73.5	67.9	85.6	80.8	83.2	80.7	80.7	74.5
28	79.9	69.5	75.5	80.2	104.8	76.6	76.9	79.3	77.9
Mean (Day 28)	75			87			78

Validity criteria fulfilled:

yes

Remarks:

difference of extremes of replicate values of the removal of the test substance <20%; degradation of the reference compound ≥60% by 14 days; residual O2 content ≥ 0.5 mg/L; oxygen uptake of the inoculum blank < 1.5 mg/L after 28 days.

Interpretation of results:

readily biodegradable

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: According to international guideline(s), GLP-compliant, performed in recognized contract research organization, no restrictions, fully adequate for assessment.

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

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 activated sludge: ARA Ergolz II, Füllinsdorf, Switzerland
- Method of cultivation / Preparation of inoculum for exposure: The sludge was washed twice with tap water by centrifugation and the supernatant liquid phase was decanted. A homogenized aliquot of the final sludge suspension was weighed, thereafter dried and the ratio of wet to dry weight was calculated. Based on this ratio, calculated amounts of wet sludge were suspended in test water to obtain a concentration equivalent to 4 g (±10%) dry material per liter. During the holding period of two days prior to use, the sludge was aerated at room temperature. Prior to use, the sludge was first thoroughly mixed and then diluted with test water to a concentration of 1 g per liter (dry weight basis). Based on the determined dry weight of this diluted activated sludge, defined amounts were added to test water to obtain a final concentration of 30 mg dry material per liter.

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

test mat.

Initial conc.:

253 mg/L

Based on:

ThOD/L

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: mineral salts medium according to guideline, prepared using purified water. The pH was adjusted to 7.4 with a diluted hydrochloride acid solution.
- Test temperature: 22 °C, maintained with a built-in thermostate and checked once a week.
- pH: 7.5 at the start of the test and 7.6 to 7.9 at the end
- pH adjusted: not necessary
- Suspended solids concentration: 30 mg/L
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: SAPROMAT D12 respirometer (Voith GmbH, Heidenheim, Germany). Principle: The consumption of oxygen in the airtight reaction vessels (total volume 500 mL, fill volume 250 mL) was determined by measuring the quantity of oxygen (produced electrolytically) required to maintain constant gas volume in the respirometer flask. Evolved carbon dioxide was absorbed by soda lime.
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: internal oxygen generating process

SAMPLING
- Sampling frequency: continuous monitoring of the cumulative amount of oxygen consumed; the cumulative oxygen demand made by each cell was recorded manually by taking a daily reading on at least each working day.

CONTROL AND BLANK SYSTEM
- Inoculum blank (2 flasks): inoculated mineral salts medium (MSM)
- Reference (2 flasks): inoculated MSM + sodium benzoate (167 mg O2/L)
- Toxicity control (1 flask): inoculated MSM + test material (255 mg O2/L) + sodium benzoate (167 mg O2/L)

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (O2 consumption)

Value:

85

Sampling time:

28 d

Remarks on result:

other: mean of two replicates

Details on results:

Mean oxygen consumption in biotic mixtures containing the test material was equivalent to 11% of the ThOD value after 2 days, 61.5% after 9 days and 85% at the end of the test (Day 28). Thus, the test material was ready biodegradable (Table 1).
In the presence of test material the degradation of sodium benzoate achieved 62% after 14 days indicating that the test substance was not inhibitory to the microbial inoculum (Table 1)

Results with reference substance:

The reference substance sodium benzoate had achieved 60% of the ThOD after approximately 3 days of incubation and 91% by Day 28 (Table 1).

Table 1   Biodegradation in the Test Flasks

 

	Percentage Biodegradation¹
Time (days)	Test item		Procedure control		Toxicity control
	Replicate No.		Replicate No.		Replicate No.
	1	2	1	2	1
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28	0 2 12 -- -- 39 45 50 54 59 -- -- 67 70 72 75 77 -- -- 81 81 82 82 83 -- 83 83 84 84	0 2 10 -- -- 39 46 51 58 64 -- -- 73 76 78 79 81 -- -- 84 85 85 86 86 -- 87 87 87 87	0 25 52 -- -- 73 75 77 78 79 -- -- 80 81 82 83 83 -- -- 86 86 86 86 86 -- 87 87 87 87	0 31 54 -- -- 78 79 80 82 84 -- -- 85 86 87 88 89 -- -- 92 93 93 93 94 -- 94 95 95 95	0 14 23 -- -- 39 42 45 48 51 -- -- 57 59 62 65 68 -- -- 77 79 80 82 83 -- 84 86 87 87
Mean (Day 28)	85		91		not applicable

¹:   Corrected for the mean oxygen uptake of the inoculum controls

--  No reading taken

Validity criteria fulfilled:

yes

Remarks:

rate of degradation of sodium benzoate was 60% of its ThOD after approximately 3 days; cumulative amount of oxygen consumed by the control mixtures was 11 and 24 mg O2/L; difference between replicates was <20%.

Interpretation of results:

readily biodegradable

Reference 3

Endpoint:

biodegradation in water: screening tests

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: According to international guideline(s), GLP-compliant, performed in recognized contract research organization, no restrictions, fully adequate for assessment.

Qualifier:

according to guideline

Guideline:

OECD Guideline 311 (Anaerobic Biodegradability of Organic Compounds in Digested Sludge: Measurement of Gas Production)

Deviations:

no

Qualifier:

equivalent or similar to guideline

Guideline:

other: ISO Standard 11734 "Water quality - Evaluation of the "ultimate" anaerobic biodegradability of organic compounds in digested sludge: Method by measurement of the biogas production"

Deviations:

not specified

GLP compliance:

yes

Oxygen conditions:

anaerobic

Inoculum or test system:

digested sludge

Details on inoculum:

- Source of inoculum: anaerobically digested sludge collected from a municipal waste water treatment plant in Hillerød. Denmark.
- Method of cultivation / Preparation of inoculum for exposure:
The sludge was pre-incubated at 35°C under an atmosphere of pure nitrogen (N2) for 6 days to reduce the content of easily degradable carbon. Before use, the sludge was filtered (approx. 1 mm mesh) while flushed with N2. In order to reduce the concentration of inorganic carbon, the sludge was washed with anaerobic mineral medium by three cycles of centrifugation and resuspension. The concentration of suspended solids (SS) in the final resuspended 'washed' sludge was 48.7 g SS/L (dry weight).

Duration of test (contact time):

60 d

Initial conc.:

50 mg/L

Based on:

ThIC

Initial conc.:

77.4 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

other: gas pressure measurements

Details on study design:

TEST CONDITIONS
- Composition of medium: mineral medium as described in the OECD TG 311, including trace elements and using titanium(lll) citrate as reducing agent (0.98 mmol/L in the final test medium).
- Additional substrate: none
- Test temperature: 35.3 ± 0.1°C
- pH: 7.0 ± 1.0
- pH adjusted: no
- Suspended solids concentration: 3.1 g SS/L
- Continuous darkness: probably yes (not indicated)

TEST SYSTEM
- Culturing apparatus: sealed glass vessels (butyl rubber stoppers and aluminium crimp seals), total volume approx. 117 mL, fill volume 100 mL; incubated stationarily in a thermostated incubator.
- Number of culture flasks/concentration: 8
- Method used to create anaerobic conditions: according to OECD TG 311
- Measuring equipment: pressure meter

SAMPLING
- Sampling frequency: weekly

CONTROL AND BLANK SYSTEM
- Inoculum blank (8 flasks): inoculated mineral medium
- Reference 1 (8 flasks): inoculated mineral medium + sodium benzoate (50 mg C/L)
- Reference 2 (8 flasks): inoculated mineral medium + phenol (50 mg C/L)
- Toxicity control (1 flask): inoculated mineral medium + test material (50 mg C/L) + phenol (50 mg C/L)
- Other: Two additional test vessels were included in each series for measurement of the pH at the start and the end of the test

Reference substance:

benzoic acid, sodium salt

Reference substance:

other: phenol

Key result

Parameter:

% degradation (inorg. C analysis)

Value:

70

St. dev.:

11

Sampling time:

60 d

Details on results:

The biodegradation of the test substance and the reference substance, phenol, in combination reached 63 ± 3% of ThIC after 60 days.

The biodegradation of the test substance tested alone was 70% of 5 mg C corresponding to 3.5 mg C, whereas biodegradation of the reference substance tested alone was 60% of 5 mg C corresponding to 3.0 mg C. The biodegradation of the two substances tested in combination is therefore expected to be 65% corresponding to 6.5 mg C of 10 mg C.

The results show that the biodegradation of the test substance and the reference substance in combination was at the same level as the biodegradation of the two substances tested individually indicating that the presence of the test substance did not inhibit the inoculum.

Results with reference substance:

The biodegradation of sodium benzoate reached 67 ± 5% of ThIC after 60 days whereas the biodegradation of phenol reached 60 ± 7% of ThIC after 60 days (see Table 1). Based on the results of the biodegradation of the reference substances, the activity of the inoculum was considered to be satisfactory.

Table 1: Anaerobic Biodegradation in the Test Assays

 

	% of ThIC (test material)
	Time(days)
Vessel No.	0	7	14	21	28	36	42	49	56	60	after acidification
A	0	1.1	8.1	12.0	23.9	51.0	55.7	57.4	58.6	58.8	59.4
B	0	8.0	15.3	23.3	53.6	67.0	69.2	70.6	72.7	73.4	75.7
C	0	3.1	7.9	10.9	37.3	44.3	45.3	45.9	47.9	48.5	50.4
D	0	3.8	9.4	15.2	50.6	62.3	64.8	66.1	68.0	68.4	70.4
E	0	7.9	10.7	13.7	16.0	46.7	61.4	69.4	73.5	75.1	76.4
F	0	3.9	10.4	14.7	42.0	61.7	64.0	64.5	65.8	66.2	65.2
G	0	7.7	14.5	21.8	58.7	73.0	76.7	78.0	80.0	80.9	82.9
H	0	7.4	14.9	18.9	51.5	66.1	68.6	69.7	72.0	74.4	75.4
Average	0	5.4	11.4	16.3	41.7	59.0	63.2	65.2	67.3	68.2	69.5

 

 

 

Table 2: Anaerobic Biodegradation in the Activity Controls

 

a) sodium benzoate

 

	% of ThIC (sodium benzoate)
	Time(days)
Vessel No.	0	7	14	21	28	36	42	49	56	60	after acidification
A	0	8.2	47.8	53.7	58.3	60.5	61.6	62.5	63.5	64.3	67.8
B	0	15.8	50.5	57.0	55.7	56.8	57.4	58.1	58.8	59.0	66.2
C	0	21.3	52.7	60.7	58.8	61.5	63.2	64.4	65.2	66.0	73.7
D	0	16.3	48.0	56.3	54.1	54.3	55.0	57.0	57.1	57.2	60.2
E	0	9.3	48.3	56.6	51.9	50.6	52.2	54.3	56.4	57.3	63.8
F	0	15.5	46.6	52.7	52.3	53.9	54.9	55.8	56.9	56.9	62.8
G	0	16.4	49.6	57.1	57.3	57.8	58.9	61.1	63.0	63.7	71.3
H	0	20.2	52.1	55.3	56.6	57.6	59.5	60.5	61.5	61.9	70.1
Average	0	15.4	49.4	56.2	55.6	56.6	57.8	59.2	60.3	60.8	67.0

 

 

b) phenol

 

	% of ThIC (phenol)
	Time(days)
Vessel No.	0	7	14	21	28	36	42	49	56	60	after acidification
A	0	5.8	12.9	51.2	52.9	53.8	54.1	54.2	55.1	55.2	54.6
B	0	2.0	9.2	46.4	51.0	54.4	55.5	56.9	58.7	59.2	59.4
C*	0	-5.3	-1.3	36.0	43.6	46.8	48.0	48.6	48.9	48.7	48.6
D	0	6.9	14.5	54.7	55.7	59.0	60.2	60.4	61.8	62.1	60.9
E	0	0.8	7.2	45.0	50.9	51.8	52.2	52.8	54.1	54.2	53.7
F	0	5.2	13.4	51.2	56.1	59.0	59.6	60.0	60.1	60.3	61.3
G	0	3.9	11.5	52.3	60.6	62.7	62.4	63.2	62.9	63.0	69.4
H	0	10.0	17.8	59.9	61.3	60.2	60.8	61.9	62.4	62.6	68.9
Average*	0	4.9	12.4	51.5	55.5	57.3	57.8	58.5	59.3	59.5	61.2

*: Vessel No. C was omitted in the calculation of the average biodegradation

 

 

 

Table 4: Anaerobic Biodegradation in the Inhibition Controls

 

	% of ThIC (test material + phenol)
	Time(days)
Vessel No.	0	7	14	21	28	36	42	49	56	60	after acidification
A	0	0.5	6.5	24.9	52.9	57.4	58.2	58.8	59.3	59.9	60.6
B	0	4.2	9.9	31.9	46.6	57.4	59.7	60.5	62.3	63.5	65.3
C	0	1.5	6.1	27.4	42.2	51.4	54.4	56.0	57.3	58.1	59.5
D	0	-1.4	5.5	17.5	40.5	56.5	60.2	61.3	62.9	63.9	64.0
E	0	-0.3	3.3	12.1	29.7	51.1	57.5	59.1	60.8	60.8	63.2
F	0	3.1	7.9	30.3	47.2	56.8	60.0	61.6	62.9	63.6	65.4
G	0	3.1	9.1	31.8	52.3	59.7	61.9	63.0	63.7	64.3	66.6
H	0	-2.0	3.4	11.8	27.9	38.8	47.8	53.5	56.1	57.2	59.4
Average	0	1.1	6.5	23.5	42.4	53.7	57.5	59.2	60.6	61.4	63.0

 

Validity criteria fulfilled:

yes

Interpretation of results:

other: ultimately anaerobically biodegradable

Description of key information

Biodegradation in water: screening tests: aerobic biodegradation 85% and 75% (ThOD) in 28 days (OECD 301F, EU C.4-D and OECD 301D, EU C.4-E)

Biodegradation in water: screening tests: anaerobic biodegradation 70% (ThIC) in 60 days (OECD 311)

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable