α-hydroxy-β,β-dimethyl-γ-butyrolactone

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:

2009-10-05 to 2009-12-15

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: OECD guideline compliant GLP compliant

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2009

Report date:

2009

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 A (Ready Biodegradability: DOC Die Away Test)

Version / remarks:

as at 1992

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.4-A (Determination of the "Ready" Biodegradability - Dissolved Organic Carbon (DOC) Die-Away Test)

Version / remarks:

as at 2008

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

α-hydroxy-β,β-dimethyl-γ-butyrolactone

EC Number:

209-963-3

EC Name:

α-hydroxy-β,β-dimethyl-γ-butyrolactone

Cas Number:

599-04-2

Molecular formula:

C6H10O3

IUPAC Name:

(3R)-3-hydroxy-4,4-dimethyloxolan-2-one

Details on test material:

- Name of test material (as cited in study report): R-Pantolactone
- Physical state: white to yellowish crystalline mass
- Analytical purity: 99.6 %
- Lot/batch No.: Bx TL 00906092
- Expiration date of the lot/batch: June 2011
- Storage condition of test material: at room temperature, protected from sunlight

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: aerobic activated sludge from municipal STP (ARA Ergolz II, Füllinsdorf, Switzerland)
- Method of cultivation: not cultivated
- Storage length: not stored, freshly obtained sludge was used
- Pretreatment: sludge was washed twice with tap water by centrifugation, decantation of supernatant and resuspension
- Concentration of sludge: 4 g (± 10%) dry matter per litre

Duration of test (contact time):

21 d

Initial test substance concentration

Initial conc.:

51.1 - 51.7 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

DOC removal

Details on study design:

TEST CONDITIONS
- Composition of medium: mineral medium was prepared in accordance with the technical guideline
- Additional substrate: not applicable
- Solubilising agent (type and concentration if used): not applicable
- Test temperature: 22 to 24 °C
- pH: 7.3 to 7.4
- pH adjusted: no
- Suspended solids concentration: 30 mg/L
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: 2000 mL Erlenmeyer flasks, final volume of test medium was 1000 mL
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: flasks were loosely covered with aluminium foil to allow air exchange between flasks and surrounding environment, contents were continuously stirred
- Measuring equipment: TOC analyser equipped with automatic sampler (Shimadzu TOC-5000A)
- Test performed in open system: yes

SAMPLING
- Sampling frequency: test item and inoculum control were sampled on days 0, 3, 7, 10, 14, 21; positive reference substance control was sampled on days 0, 3, 7, 14 and 21; toxicity control was sampled on days 0, 7, 14 and 21
- Sampling method: one sample of about 10 mL was taken from each test flask per sampling date; prior to sampling, losses by water evaporation were determined and were compensated by adding purified water
- Sample storage before analysis: samples were analysed immediately or stored at -2 to -4 °C for 24 hours

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Abiotic sterile control: no
- Toxicity control: yes

Reference substance

Reference substance:

acetic acid, sodium salt

Remarks:

for details see above under "reference substance"

Results and discussion

Preliminary study:

not applicable

Test performance:

- Biodegradation started between experimental days 3 and 7
- 70% DOC removal was seen during a 10-day window in the flasks with test substance and activated sludge
- Complete DOC removal was seen within a test period of 21 days
- Postive reference substance was degraded (> 90%) within seven days
- The substance was not inhibiting to the activity of the active sludge

% Degradation

% Degradation 1

Parameter:

% degradation (DOC removal)

Value:

56 - 67

Sampling time:

7 d

% Degradation 2

Parameter:

% degradation (DOC removal)

Value:

100

Sampling time:

14 d

Details on results:

See tables under "Any other information on results"

BOD5 / COD results

Results with reference substance:

The positive control substance was degraded by at least 90% with 7 days.

Any other information on results incl. tables

Table 1: Dissolved organic carbon concentrations (DOC) in the test flasks

Time (days)	Dissolved organic carbon (DOC) in mg/L^1, 2
	Test substance			Positive control			Inoculum control			Toxicity control
	Replicate No			Replicate No			Replicate No			Replicate No
	1	2	Mean^3	1	2	Mean^3	1	2	Mean	1^3
0	31.5	30.5	27.7	32.4	31.6	28.7	4.3	2.3	3.3	56.5
3	30.8	31.3	28.5	3.7	2.4	0.5	1.9	3.3	2.6	--
7	11.9	14.4	10.7	4.4	3.4	1.3	2.7	2.5	2.6	28.2
10	2.9	3.1	0.2	--	--	--	2.5	3.2	2.9	--
14	2.6	2.1	0.1	3.2	2.3	0.5	2.4	2.2	2.3	1.5
21	2.3	2.2	0.0	2.3	2.5	0.2	2.3	2.2	2.3	1.6
1) Mean values of at least triplicate measurements per sample; 2) Sampling was ended before 28 days because the biodegradation curve reached a plateau for three determinations; 3) Values corrected for the inoculum controls; -- not determined

Table 2: Percentage biodegradation in the test flasks

Time (days)	Percentage biodegradation^1, 2
	Test			Positive control			Toxicity control
	Replicated No.			Replicated No.			Replicated No.
	1	2	Mean	1	2	Mean	1
0	0	0	0	0	0	0	0
3	0	-6	-3	96	101	98	--
7	67	56	61	94	97	95	50
10	100	99	99	--	--	--	--
14	99	101	100	97	100	98	97
21	100	100	100	100	99	99	97
1) Corrected for inoculum controls; 2) Sampling was ended before 28 days because the biodegradation curve reached a plateau for three determinations; -- not determined

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The substance was found to be readily biodegradable in a valid study according to the DOC Die Away test.

Executive summary:

The ready biodegradability of the test substance R-Pantolactone was studied under GLP in accordance with OECD TG 301-A (DOC Die Away test). Non-adopted activated sludge freshly collected from a municipal STP treating mainly domestic sewage was used in the test, which was suspended in standard mineral medium prepared according to the guideline at a concentration of 30 mg/L suspended matter. The concentration of test medium in the flasks was about 50 mg/L. The study was conducted in 2-L Erlenmeyer flasks that were loosely covered during the test. The test volume of continuously stirred test medium was 1000 mL per flask, the test temperature was 22 to 24 °C and the test was performed in the dark. In parallel, flasks with the inoculum alone, with the positive control sodium benzoate and with a mixture of positive reference substance and test substance (toxicity control) were tested under similar conditions. The reference substance was degraded by more than 90% within 14 days and the test substance did not inhibit the activity of the activated sludge. The test was considered as valid. Biodegradation of the test substance commenced between day 3 and 7 and reached more than 70% within a 10-day window. Complete biodegradation of the test substance was observed within 21 days and the test was ceased as biodegradation reached a plateau for three consecutive measurements.