Fatty acids, tall-oil, polymers with glycidyl neodecanoate

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:

From July 2, 2015 to August 5, 2015

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:

no

Qualifier:

according to guideline

Guideline:

EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution 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 and pretreatment of inoculum: The sludge was taken from the activation basin of the ESN (Stadtentsorgung Neustadt) sewage treatment plant, Im Altenschemel, NW-Lachen-Speyerdorf. The sludge was filtrated, washed with tap water twice, then washed with and re-suspended in test medium. It was then aerated until use. The dry matter was determined with 4,540 mg suspended solids/L.

Duration of test (contact time):

28 d

Initial conc.:

27 mg/L

Based on:

test mat.

Initial conc.:

20 mg/L

Based on:

other: organic carbon

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

Preparations:
The medium was prepared from the stock solutions. The stock solution of the positive control was prepared and its TOC was measured. The inoculum was taken from its source, washed, aerated and the dry matter was determined. The test vessels were filled with medium and inoculum. Then, all flasks were aerated for 72 h with purified, CO2 free, moistened air to purge the system of CO2. On the day of the start of the test, CO2 free medium and inoculum was filled into the test flask.

The number of flasks were as follow:
- 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 substance, mineral medium and inoculum
- Abiotic control: 1, containing test substance, mineral medium and HgCl2
- Toxicity control: 1, containing test substance, positive control, mineral medium and inoculum

TEST CONDITIONS:
Inoculum concentration: 25.0 mg/L
Temperature: 20.0 – 23.1°C

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 were added to each test flask in order to drive off dissolved CO2. On Day 29, samples from both scrubber flasks were taken.

CO2 DETERMINATION:
Analyses of the emitted CO2 were made by IC measurement using the carbon analyser TOC multi N/C 2100S, Analytik Jena. With the exception of one single measurement of one control replicate, each sample was measured in duplicate or triplicate, respectively (depending on the variation between the measurements). The carbon analyser was calibrated with freshly prepared reference solutions containing potassium hydrogen phthalate (TC), sodium hydrogen carbonate and sodium carbonate (IC) once a week. After every start, quality control samples were measured.

Reference substance:

aniline

Remarks:

26 mg/L

Key result

Parameter:

% degradation (CO2 evolution)

Value:

53

Sampling time:

28 d

Details on results:

Degradation behaviour of positive control and toxicity control was normal. Abiotic degradation was not observed. Both replicates of the test substance showed very good correspondence. If degradation in the toxicity flask is below 25% after 14 d, the test substance can be considered as toxic towards the inoculum. As degradation in the toxicity flask was 64% after 14 d, the test substance can be stated as “not toxic towards the inoculum in a concentration of 27.3 mg/L”. Ready degradability is defined in the guidelines as degradation surpassing 60% within 10 d after reaching a level of 10%. Therefore, the test substance can be considered as “not readily biodegradable”. Because the test substance is a mixture, the 10 d window must not be taken into account. Nevertheless degradation did not reach 60% within 28 d though. Therefore, the test substance is considered as “not ultimately biodegradable within 28 d, either. From chemistry perspective, test substance is similar to a lubricant. Currently a lubricant can be stated as inherently biodegradable if degradation was between 20% and 60% after 28 d. Therefore based on a degradation of 53% at the end of the 28 d period the test substance is very likely inherently biodegradable. No observations were made which might cause doubts concerning the validity of the study outcome.

1. The test substance is considered as not readily biodegradable.
2. The degree of biodegradation reached 53% after 28 d.
3. The 10 d window began on Day 3, at its end, 42% were reached, missing the pass level of 60% given in the OECD Guideline.
4. Abiotic degradation was not observed.

Results with reference substance:

The reference substance aniline was sufficiently degraded to a mean of 75.9% after 14 d, and to a mean of 86.8% after 28 d of incubation, based on CO2 evolution, thus confirming the suitability of the used activated sludge inoculum.

Following table shows the percentage biodegradation:

Table 1: Degradation values in percent

Day	Positive control 1	Positive control 2	Positive control mean	Test 1	Test 2	Test mean	Abiotic control	Toxicity control
2	-0.9	0.2	-0.3	7.7	7.0	7.4	1.6	2.8
4	9.9	12.8	11.4	19.8	19.1	19.4	1.7	21.9
7	48.9	53.0	51.0	29.1	32.9	31.0	1.3	44.3
9	58.4	59.1	58.8	32.5	34.0	33.3	1.2	51.1
11	64.7	66.4	65.6	36.1	37.6	36.8	0.9	57.2
14	76.7	75.2	75.9	41.2	46.4	43.8	0.8	64.0
18	81.0	82.1	81.5	47.2	49.7	48.5	0.4	69.1
23	83.9	84.8	84.3	50.4	49.6	50.0	0.4	69.6
29	84.8	88.8	86.8	52.2	52.9	52.6	-1.0	72.1

The test substance is a mixture, the 10 d window must not be taken into account. Nevertheless degradation did not reach 60% within 28 d, though. Therefore, the test substance is considered as “not ultimately biodegradable within 28 d”, either. From chemistry perspective, test substance is similar to a lubricant. Currently a lubricant can be stated as inherently biodegradable if degradation was between 20 and 60% after 28 d. Therefore based on a degradation of 53% at the end of the 28 d period the test substance is very likely inherently biodegradable.

Validity criteria fulfilled:

yes

Interpretation of results:

inherently biodegradable, fulfilling specific criteria

Conclusions:

Under the study conditiond, the test substance was considered to be ‘not readily biodegradable’.

Executive summary:

A study was conducted to assess the ready biodegradability of the test substance according to OECD Guideline 301B and EU Method C.4 -C, in compliance with GLP. Microbial inoculum (25 mg/L) was added to each preparation bottle of test substance, reference control (aniline), blank control and toxicity control and kept at a constant temperature (20 - 23.1°C) for up to 29 d. Degradation was assessed by the determination of carbon dioxide evolution on Days 0, 2, 4, 7, 9, 11, 14, 18, 23 and 29. The test substance was degraded 53% by 28 d. No toxicity of the test substance was observed as degradation was >25% within 14 d. The reference compound showed 86.8% degradation after 28 d incubation. Under the study conditions, the test substance was considered to be ‘not readily biodegradable’ (Muckle, 2015).

Key value for chemical safety assessment

Biodegradation in water:

inherently biodegradable, fulfilling specific criteria

Additional information

A study was conducted to assess the ready biodegradability of the test substance according to OECD Guideline 301B and EU Method C.4 -C, in compliance with GLP. Microbial inoculum (25 mg/L) was added to each preparation bottle of test substance, reference control (aniline), blank control and toxicity control and kept at a constant temperature (20 - 23.1°C) for up to 29 d. Degradation was assessed by the determination of carbon dioxide evolution on Days 0, 2, 4, 7, 9, 11, 14, 18, 23 and 29. The test substance was degraded 53% by 28 d. No toxicity of the test substance was observed as degradation was >25% within 14 d. The reference compound showed 86.8% degradation after 28 d incubation.Under the study conditions, the test substance was considered to be ‘not readily biodegradable’ (Muckle, 2015).