ε-Caprolactone, oligomeric reaction products with 2,2'-oxydiethanol

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:

28 August 2017 to 26 September 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

Deviations:

yes

Remarks:

Temperature range was 19.4 to 21.6°C instead of 20 to 24°C. Positive control degradation was in the normal range and is therefore considered uncritical.

Qualifier:

according to guideline

Guideline:

EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Appearance viscous, colorless liquid
CAS No. 36890-68-3
EINECS-No. 500-092-7

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

Activated sludge was taken from the aeration basin of the ESN (Stadtentsorgung Neustadt) sewage treatment plant, Im Altenschemel, NW-Lachen-Speyerdorf.
Date of collection: 25. Aug. 2017, batch no: 20170825.

The sludge was filtrated, washed with tap water (2x), then washed with and re-suspended in test medium. It was then aerated until use. The dry matter was determined as 4120 mg suspended solids/L and the inoculum was applied to the test at a concentration of 25 mg dry solids/L.

Duration of test (contact time):

28 d

Initial conc.:

39.3 mg/L

Based on:

test mat.

Initial conc.:

20 mg/L

Based on:

TOC

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST PREPARATIONS:
The mineral medium was prepared from the stock solutions A (10 mL), B (1 mL), C (1 mL) and D (1 mL) and made up to 1000 mL with water. The stock solution of the positive control (aniline) was prepared and its DOC measured.
Test vessels (2000 mL-SCHOTT-flasks) were filled with medium and inoculum. Then, all flasks were aerated for 72 hours with purified, CO2-free, moistened air to purge the system of CO2.


EXPERIMENTAL PARAMETERS:
Flask volume 1500 mL
Apparatus blanks 2, containing mineral medium only
Blank Controls 2, containing mineral medium and inoculum
Positive control flasks 2, containing positive control, mineral medium and inoculum
Test flasks 2, containing test item, mineral medium and inoculum
Abiotic control 1, containing test item, mineral medium and HgCl2
Toxicity control 1, containing test item, positive control, mineral medium and inoculum
Inoculum concentration: 25.0 mg/L
Temperature 19.4 – 21.6 °C

The test was performed with a nominal start concentration of 20 mg organic carbon/L. Test item (test 1 = 39.1 mg/L; test 2 = 39.5 mg/L) and positive control (26.8 mg/L) were added to the flasks. Test vessels were incubated under aerobic conditions in the dark.


APPARATUS:
Test vessels were aerated with purified (by activated charcoal) CO2-scrubbed, moistened air. Scrubbing of CO2 was achieved by bubbling the purified air through a flask containing 1.5 M NaOH. To maintain a check on the absence of CO2 the air was then led through a flask containing a solution of Ba(OH)2 before reaching the test vessels.

Magnetic stirrers were used to prevent deposition of inoculum.

Emitted CO2 was trapped in 0.25 M NaOH. Two scrubbers containing 100 mL each were connected in series to the test vessels. The initial IC value of the 0.25 M NaOH was separately determined in each flask.


SAMPLING:
From each front scrubber flask, 10 samples were taken in order to determine the emitted CO2 (on day 0, 2, 4, 7, 9, 11, 14, 18, 23 and 29). The sample volume was 1 mL. The resulting change in the volume of the front flask was considered in the calculation of emitted CO2.
On day 28, 5 mL HCl 2 M was added to each test flask in order to drive off dissolved CO2. On day 29, samples from both scrubber flasks were taken.

Reference substance:

aniline

Preliminary study:

Not required.

Test performance:

All validity criteria specified by the guideline were met, therefore the test is considered to be valid.
Degradation behaviour of positive control and toxicity control was normal. Abiotic degradation was not observed. Both replicates of the test item showed good correspondence.
Degradation in the toxicity flask was 72.5 % after 14 days (i.e. >25%), therefore the test item can be stated as “not toxic towards the inoculum in a concentration of 39.4 mg/L”.

Key result

Parameter:

% degradation (CO2 evolution)

Value:

90

Sampling time:

29 d

Remarks on result:

other: Mean value

Parameter:

% degradation (CO2 evolution)

Value:

87.2

Sampling time:

29 d

Remarks on result:

other: Test 1

Parameter:

% degradation (CO2 evolution)

Value:

92.9

Sampling time:

29 d

Remarks on result:

other: Test 2

Details on results:

The test item, ε-Caprolactone, oligometric reaction products with 2,2'-oxydiethanol, achieved a mean of 90% biodegradation (based on CO2 evolution) after 28 days. The 10-day window began when biodegradation crossed the 10% threshold on day 4 and closed on day 14 when degradation had reached 69% degradation. Since the test item is a UVCB and not a pure substance, the 10-day window may be waived. Nevertheless, CO2 production in this study exceeded 60% of the theoretical yield in 28 days and within the 10-d window and the test item is therefore considered as readily biodegradable, having fulfilled both performance criteria.

Results with reference substance:

The reference substance (aniline) achieved a mean of 70% degradation after 9 days and 88.8% degradation after 28 days, thereby meeting the validity criteria.

Percentage degradation values

Day	Positive Control 1	Positive Control 2	Positive Control Mean	Test 1	Test 2	Test Mean	Abiotic Control	Toxicity Control
2	0.4	-3.2	-1.4	-1.8	-1.0	-1.4	0.7	2.1
4	16.0	8.7	12.4	10.2	22.4	16.3	0.8	25.1
7	52.8	54.2	53.5	52.7	39.2	46.0	0.6	51.8
9	69.0	70.5	69.7	64.3	53.9	59.1	0.3	52.7
11	79.7	78.1	78.9	68.2	64.5	66.3	-0.1	63.3
14	84.3	79.4	81.9	66.5	71.3	68.9	0.1	72.5
18	88.5	80.7	84.6	76.3	80.8	78.5	-0.4	75.0
23	84.8	78.5	81.7	79.7	83.1	81.4	-1.1	79.9
29	93.1	84.5	88.8	87.2	92.9	90.0	-2.1	88.0

As the measured IC values in the test flasks and the abiotic control are very low, measurement uncertainties lead to negative degradation values while in fact no degradation has taken place.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The test item, ε-Caprolactone, oligometric reaction products with 2,2'-oxydiethanol, achieved a mean of 90% biodegradation (based on CO2 evolution) after 28 days, and fulfilled the 10-day window criterion. The test item is readily biodegradable.

Executive summary:

A study was conducted according to OECD 301B and EU-method C.4-C and in compliance with GLP to investigate the ready biodegradability of the test item, item ε-Caprolactone, oligometric reaction products with 2,2'-oxydiethanol.

The test item achieved a mean of 90% degradation after 28 days, with a mean of 69% degradation at the end of the 10-day window. Given that the test item is a substance with a complex composition containing different constituents (UVCB) and not a pure substance, the 10-d window consideration may be waived. However, since the test item achieved >60% biodegradation within 28 days and fulfilled the 10 -day window criterion it may be considered to be unambiguously “readily biodegradable within 28 days”.

The test substance, ε-Caprolactone, oligometric reaction products with 2,2'-oxydiethanol is therefore concluded to be readily biodegradable.

Description of key information

A study was conducted according to OECD 301B and EU-method C.4-C and in compliance with GLP to investigate the ready biodegradability of the test item, item ε-Caprolactone, oligometric reaction products with 2,2'-oxydiethanol.

The test item achieved a mean of 90% degradation after 28 days, with a mean of 69% degradation at the end of the 10-day window. Given that the test item is a substance with a complex composition containing different constituents (UVCB) and not a pure substance, the 10-d window consideration may be waived. However, since the test item achieved >60% biodegradation within 28 days and fulfilled the 10 -day window criterion it may be considered to be unambiguously “readily biodegradable within 28 days”.

The test substance, ε-Caprolactone, oligometric reaction products with 2,2'-oxydiethanol is therefore concluded to be readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater