Poly[oxy(methyl-1,2-ethanediyl)], α-hydro-ω-hydroxy-, ether with 2-ethyl-2-(hydroxymethyl)-1,3-propanediol (3:1), 2-propenoate

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 June 27, 2016 to July 27, 2016

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:

but uncritical

Qualifier:

according to guideline

Guideline:

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

Deviations:

yes

Remarks:

but uncritical

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Remarks:

concentration in the test: 25.0 mg dry matter/L

Details on inoculum:

Activated sludge from a biologic sewage treatment plant was used. The chosen plant was treating mostly domestic sewage. The sludge was taken from the activation basin of the ESN (Stadtentsorgung Neus tadt) sewage treatment plant, Im Altenschemel, NW-Lachen-Speyerdorf (batch no: 20160219). The sludg e 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 with 3900 mg suspended solids/L.

Duration of test (contact time):

28 d

Initial conc.:

32.9 mg/L

Based on:

other: nominally 20 mg organic carbon/L

Parameter followed for biodegradation estimation:

CO2 evolution

Remarks:

emitted CO2 were made by IC measurement using the carbon analyser TOC

Details on study design:

- The medium was prepared from the stock solutions. The stock solution of the positive control was p repared and its TOC was measured. The inoculum was taken from its source, washed, aerated and the d ry matter was determined. The test vessels 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. On the day of th e start of the test, CO2-free medium and inoculum was filled into the test flask.
- 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 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
Inoculum concentration: 25.0 mg/L
Temperature: 19.4 – 22.6 °C
Duration: 28 days
The test was performed with a nominal start concentration of 20 mg organic carbon/L
- The 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 th e volume of the front flask was considered in the calculation of emitted CO2 (see also chapter 8.2.1). 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.
- CO2 Determination: analyses of the emitted CO2 were made by IC measurement using the carbon analyser TOC.

Reference substance:

aniline

Key result

Parameter:

% degradation (CO2 evolution)

Remarks:

made by IC measurement

Value:

65

Sampling time:

28 d

Details on results:

The following data were determined for the test substance:
- 10-day-window (day 15 – 25): degradation at the end = 51%
- degradation at the end of the test (28 days) = 65%
Pass level following guideline: 60% at the end of the test for mixtures. As degradation reached the target of 60% within 28 days, the test substance was considered as readily biodegradable.
NB. 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 days, the test substance can be considered as toxic towards the inoculum. As degradation in the toxicity flask was 44% after 14 days, the test substance could be stated as “not toxic towards the inoculum in a concentration of 33.0 mg/L”.

Results with reference substance:

Degradation of the positive control (aniline) was 66% after 9 days

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

Under the study conditions, the test substance was considered as ‘readily biodegradable’.

Executive summary:

A study was conducted to determine the biodegradation in water of the test substance according to OECD Guideline 301 B and EU Method C.4-C (CO2 evolution test), in compliance with GLP. The substance was tested in duplicate at the concentration of 20 mg organic carbon/L (corresponding to 32.9 mg test substance/ L) for a duration of 28 days. Test and reference substances (positive control: aniline and toxicity control: test substance plus aniline) were added to the bottles containing the microbial organisms (domestic sludge) and mineral components followed by sampling on Day 0, 2, 4, 7, 9, 11, 14, 18, 23 and 29 to measure CO2 evolution. The amount of CO2 produced was determined by inorganic carbon (IC) measurement using the carbon analyser. Each sample was measured in duplicate or triplicate depending upon the variation. The test substance revealed 65% biodegradation (based on IC) in the duplicate test bottles. No toxicity of the test substance was observed in the toxicity control at a concentration of 33 mg/L; there was 44% degradation after 14 days. Abiotic degradation was not observed. Degradation of the positive control was 66% after 9 days. All validity criteria were met. Under the study conditions, the test substance was considered to be readily biodegradable (Muckle, 2016).

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

A study was conducted to determine the biodegradation in water of the test substance according to OECD Guideline 301 B and EU Method C.4-C (CO2 evolution test), in compliance with GLP. The substance was tested in duplicate at the concentration of 20 mg organic carbon/L (corresponding to 32.9 mg test substance/ L) for a duration of 28 days. Test and reference substances (positive control: aniline and toxicity control: test substance plus aniline) were added to the bottles containing the microbial organisms (domestic sludge) and mineral components followed by sampling on Day 0, 2, 4, 7, 9, 11, 14, 18, 23 and 29 to measure CO2 evolution. The amount of CO2 produced was determined by inorganic carbon (IC) measurement using the carbon analyser. Each sample was measured in duplicate or triplicate depending upon the variation. The test substance revealed 65% biodegradation (based on IC) in the duplicate test bottles. No toxicity of the test substance was observed in the toxicity control at a concentration of 33 mg/L; there was 44% degradation after 14 days. Abiotic degradation was not observed. Degradation of the positive control was 66% after 9 days. All validity criteria were met. Under the study conditions, the test substance was considered to be readily biodegradable (Muckle, 2016).