1-hydroxyoctan-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:

Sept-Oct 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

This is a Klimisch 1 rated GLP study conducted on the registered substance

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Lot/Batch 1203/16/100

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, non-adapted

Details on inoculum:

Activated sludge from the municipal wastewater treatment plant Breisgauer Bucht was used as test system. The treatment plant has a capacity of 600 000 inhabitant equivalents and clarifies predominantly domestic wastewater. Sampling date of activated sludge was 25 September 2018. The activated sludge was kept aerated until use at test temperature. The activated sludge was washed twice by settling the sludge, decanting the supernatant and re-suspending the sludge in chlorine-free tap water. Dry solid of the activated sludge was determined as 3.9 g/L by weight measurements before and after drying at 105°C (mean of triplicate measurements).

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

ThOD

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

In total three reactors containing the test item, three reactors containing only inoculum (blank), three reactors containing the reference compound (reference) and one reactor containing reference compound and test item (toxicity control) were set up.

The test flasks were filled and tempered to the incubation temperature for one hour. Afterwards, 1.3 mL of the inoculum were added into each flask except the abiotic control, one sodium hydroxide pellet was added to each rubber quiver inserted in the flasks and the flasks were sealed tightly with the measuring heads and the test was started.

After 28 days the data were read out and the pH in the flasks was measured.

Reference substance:

acetic acid, sodium salt

Test performance:

The oxygen uptake of the inoculum blank was in the range of 20 - 30 mg O2/L and did not exceed 60 mg O2/L in 28 days (presently 23.4 mg O2/L).

The pH value in the test and blank bottles was within the specified range of 6 – 8.5 (presently 7.6). In the reference and toxicity control vessels the pH was above 8.5, however the oxygen consumption in those vessels was greater than 60% within the test duration.

The difference of extremes of replicate values of the test item degradation extents was less than 20% (presently 2.5%).

The biodegradation of the reference item reached the pass level of 60% ThOD by day 8 (presently 71.2%).

The degradation extent in the toxicity control was above 25% in 14 days based on ThOD (presently 35.6% on day 4)

Taking all of the above into account the test is considered valid according to OECD Test Guideline 301 F (July 1992).

Parameter:

% degradation (O2 consumption)

Value:

48.7

Sampling time:

4 d

Parameter:

% degradation (O2 consumption)

Value:

65.6

Sampling time:

8 d

Parameter:

% degradation (O2 consumption)

Value:

72.1

Sampling time:

12 d

Parameter:

% degradation (O2 consumption)

Value:

74.1

Sampling time:

16 d

Parameter:

% degradation (O2 consumption)

Value:

75

Sampling time:

20 d

Parameter:

% degradation (O2 consumption)

Value:

74.2

Sampling time:

24 d

Key result

Parameter:

% degradation (O2 consumption)

Value:

76.8

Sampling time:

28 d

Details on results:

The biodegradation of the test item was 76.8% within 28 days (mean of three replicates). On day 8 the degradation extent was already above 60% (65.6%, mean of three replicates) and the criterion for ready biodegradation is therefore met.

The degradation in the toxicity control reached a value higher than 25% within 4 days (35.6%). According to the validity criterion of the guideline OECD 301 the test item had no toxic or inhibitory effect to the inoculum.

Results with reference substance:

The reference compound sodium acetate reached the pass level for ready biodegradability (60% ThOD within a 10-day window) within 8 days (71.2%).

Day	%Biodegradation Test Item				Tox Control	%Biodegradation Ref Item
	Rep 1	Rep 2	Rep 3	Mean		Rep 1	Rep 2	Rep 3	Mean
0	0	0	0	0.0	0	0	0	0	0.0
4	48.7	48.7	48.7	48.7	35.6	54.3	57.1	54.3	55.2
8	64.7	64.7	67.5	65.6	48.1	70.3	73.1	70.3	71.2
12	71.2	71.2	74	72.1	59.6	76.9	76.9	76.9	76.9
16	73.1	73.1	76	74.1	69.2	78.8	81.3	78.8	79.6
20	74.1	74.1	76.9	75.0	73.7	79.4	79.4	79.4	79.4
24	75.1	72.3	75.1	74.2	75.3	80.6	77.6	77.6	78.6
28	77.6	75.1	77.6	76.8	78.3	83.6	80.6	77.6	80.6

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

On the basis of this test 1 -hydroxyoctan-2 -one is considered to be ready biodegradable meeting the 10d window.

Executive summary:

An OECD 301F study was carried out in accordance with GLP to investigate the ready biodegradability of the registered substance 1 -hydroxyoctan-2 -one.

The biodegradation of the test item was 76.8% within 28 days (mean of three replicates). On day 8 the degradation extent was already above 60% (65.6%, mean of three replicates) and the criterion for ready biodegradation is therefore met.

The reference compound sodium acetate reached the pass level for ready biodegradability (60% ThOD within a 10-day window) within 8 days (71.2%).

The degradation in the toxicity control reached a value higher than 25% within 4 days (35.6%). According to the validity criterion of the guideline OECD 301 the test item had no toxic or inhibitory effect to the inoculum.

On the basis of this test 1 -hydroxyoctan-2 -one is considered to be ready biodegradable meeting the 10d window.

Description of key information

An OECD 301F study was carried out in accordance with GLP to investigate the ready biodegradability of the registered substance 1 -hydroxyoctan-2 -one.

The biodegradation of the test item was 76.8% within 28 days (mean of three replicates). On day 8 the degradation extent was already above 60% (65.6%, mean of three replicates) and the criterion for ready biodegradation is therefore met.

The reference compound sodium acetate reached the pass level for ready biodegradability (60% ThOD within a 10-day window) within 8 days (71.2%).

The degradation in the toxicity control reached a value higher than 25% within 4 days (35.6%). According to the validity criterion of the guideline OECD 301 the test item had no toxic or inhibitory effect to the inoculum.

On the basis of this test 1 -hydroxyoctan-2 -one is considered to be ready biodegradable meeting the 10d window.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater