Glycerol, propoxylated, esters with acrylic acid, reaction products with diethylamine

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:

2016-11-02 to 2017-

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, predominantly domestic, non-adapted

Details on inoculum:

The inoculum was obtained on 22 November 2016 from the activated sludge of the biological wastewater treatment plant from Mourenx (France, 64) which handles predominantly domestic sewage.

On arrival at the laboratory, the sludge (around 2.5 L) was centrifuged at approximately 20°C for 10 min at 1000 g; the solid sewage inoculant portion was re-suspended in dilution water in order to keep the concentration unchanged with respect to the sample. The inoculum was preconditioned 48 hours (aeration) until the flasks were inoculated.

Sub-samples of the homogenised sludge were dried in an oven at approximately 105°C and the suspended solids content was determined to be 4.29 g/L.

The inoculum was not adapted to the test item before the biodegradation test.

Duration of test (contact time):

56 d

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

A total of 9 bioreactors were used; 2 each for test item, blank control, reference item control, emulsifying agent control and one for toxicity control.

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (O2 consumption)

Value:

64.1

Sampling time:

28 d

Remarks on result:

other: Not considering nitrification; Not passing 10d window criterion

Parameter:

% degradation (O2 consumption)

Value:

56.6

Sampling time:

28 d

Remarks on result:

other: Considering the occurrence of nitrification

Parameter:

% degradation (O2 consumption)

Value:

87.8

Sampling time:

56 d

Remarks on result:

other: Not considering nitrification

Parameter:

% degradation (O2 consumption)

Value:

77.5

Sampling time:

56 d

Remarks on result:

other: Considering the occurrence of nitrification

Theoretical Oxygen Demand

The theoretical oxygen demand of the test item is ThODNH4 = 2.0588 mg O2/mg (based on CHN analysis). This calculation does not take into account any other constituents/impurities within the substance as supplied and is calculated by assuming formation of ammonium, water and carbon dioxide (no nitrification). If considering nitrification, ThODNO3 = 2.3330 mg O2/mg.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable, but failing 10-day window

Conclusions:

According to the OECD 301 guideline, the pass levels for ready biodegradability is 60% of ThOD for respirometric methods. This pass value has to be reached in a 10-d window within the 28-d period of the test; the 10-d window begins when the degree of biodegradation has reached 10% ThOD and must end before day 28 of the test.

In this study the, 10% biodegradation of ThOD starts at day 12 and the biodegradation reached the pass level 60% of ThOD between day 28 (without nitrification) and day 29 if considering nitrification (i.e. > 10 days). Consequently, the test item Glycerol, propoxylated, esters with acrylic acid, reaction products with diethylamine was not readily biodegradable under the conditions of the test.

Executive summary:

The study was conducted in accordance with procedures outlined in OECD Guideline 301F (1992). The ready biodegradability ofGlycerol, propoxylated, esters with acrylic acid, reaction products with diethylamine was assessed over a 56 days period (in the absence of the CHN analysis at Day 28, the test was extended until Day 56 as the test item biodegradation was close to the pass level (60%) at Day 28).

The test was conducted at a nominal loading rate of 100 mg/L. As test item was suspected to be difficult to dissolve, its dispersibility was improved by use of an emulsifying agent (Symperonic P103) as described in ISO 10634 standard.

A total of 9 bioreactors were used; 2 each for test item, blank control, reference item control, emulsifying agent control and one for toxicity control.

The time to reach the different biodegradation levels is detailed in the table below:

 

Biodegradation level	Without nitrification			With nitrification
	Replicate 1 (Ft1)	Replicate 2 (Ft2)	Average	Replicate 1 (Ft1)	Replicate 2 (Ft2)	Average
10%	Day 11	Day 13	Day 12	Day 11	Day 13	Day 12
60%	Day 17	Day 30	Day 28	Day 20	Day 35	Day 29
10-D window success	Yes	No	No	Yes	No	No

 

The test item was not readily biodegradable under the conditions of the test as it failed to achieve a transition from 10% to 60% degradation in a 10-day window during the 28 days test.

 

The test item was not considered to be inhibitory to the microbial inoculum since the biodegradation observed in the toxicity control bioreactor was not less than 25% occurred within 14 days.

  

The definitive test met the validity criteria of the test guideline detailed as follows:

 

§ the difference of extremes of replicate values of the removal of the test item at the end of the extended period (i.e. 56 days) was less than 20%

§ the percentage degradation of the reference compound has reached the pass levels by day 14: 91.3% (with or without nitrification)

§ the biodegradation observed in the toxicity control bioreactor was not less than 25% occurred within 14 days: 44.2% (without nitrification) and 44.1 % (with nitrification)

§ the oxygen uptake of the inoculum blank was not greater than 60 mg/l in 56 days: 20.6 mg/L (blank control) and 36.3% (emulsifying control)

§ the pH value was not outside the 6 -8.5 range: min 7.2, max 7.7

The test is thus considered as valid.

Description of key information

In a screening biodegradation test performed according to OECD Test Guideline 301F, the test substance Glycerol, propoxylated, esters with acrylic acid, reaction products with diethylamine (CAS 162492-10-6) reached a biodegradation level of 64.1% at Day 28 (considering no nitrification), but the 10-day window criterion was not passed. As the validity criteria were fulfilled, the test substance is considered as readily biodegradable but failing the 10-day window criterion.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable but failing 10-day window