Reaction products of n-octanol and acrylic acid, first distillation pitch

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 January 4, 2012 to February 2, 2012

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

Qualifier:

according to guideline

Guideline:

ISO DIS 9439 (Ultimate Aerobic Biodegradability - Method by Analysis of Released Carbon Dioxide)

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: ISO Standard 10634 "Water Quality - Guidance for the preparation and treatment of poorly water-soluble organic compounds for the subsequent evaluation of their biodegradability in an aqueous medium"

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, domestic, adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Waterschap Aa en Maas', 's-Hertogenbosch, The Netherlands.
- Preparation of inoculum for exposure: the sludge was allowed to settle (32 minutes) and the supernatant liquid was used as inoculum.
- Concentration of sludge: 10 mL/L of mineral medium.
- Initial cell/biomass concentration: 3.4 g/L

Duration of test (contact time):

28 d

Initial conc.:

14.6 mg/L

Based on:

other: TOC

Initial conc.:

14.65 mg/L

Based on:

other: TOC

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium:
1 litre mineral medium contains: 10 mL of solution (A), 1 mL of solutions (B) to (D) and Milli-RO water.
A) 8.50 g KH2PO4
21.75 g K2HPO4
67.20 g Na2HPO4.12H2O
0.50 g NH4Cl
dissolved in Milli-Q water and made up to 1 litre, pH 7.4 ± 0.2
B) 22.50 g MgSO4.7H2O dissolved in Milli-Q water and made up to 1 litre.
D) 0.25 g FeCl3.6H2O dissolved in Milli-Q water and made up to 1 litre.

- Additional substrate: 0.0125 M Ba(OH)2 (Boom, The Netherlands), stored in a sealed vessel to prevent absorption of CO2 from the air.
- Test temperature: 21.9 - 22.9ºC
- pH: 7.5 - 7.8
- pH adjusted: no
- Aeration of dilution water: The pre-incubation medium was aerated with synthetic air overnight.
- Suspended solids concentration: 3.4 g/L
- Continuous darkness: no

TEST SYSTEM
- Culturing apparatus: 2 litre all-glass brown coloured bottles.
- Number of culture flasks/concentration: 1
- Measuring equipment: CO2-absorber.
- Details of trap for CO2 and volatile organics if used: Each time the CO2-absorber nearest to the test bottle was removed for titration; each of the remaining two absorbers was moved one position in the direction of the test bottle. A new CO2-absorber was placed at the far end of the series. Phenolphthalein (1% solution in ethanol, Merck) was used as pH-indicator.

SAMPLING
- Sampling frequency: Titrations were made every second or third day during the first 10 days, and thereafter at least every fifth day until the 28th day, for the inoculum blank and test suspension. Titrations for the positive and toxicity control were made at least 14 days.
- Sampling method: The CO2 produced in each test bottle reacted with the barium hydroxide in the gas scrubbing bottle and produced was determined by titrating the remaining Ba(OH)2 with 0.05 M standardized HCl.

CONTROL AND BLANK SYSTEM
- Inoculum blank: only inoculum.
- Toxicity control: test substance, reference substance and inoculum.
- Other :Positive control: reference substance and inoculum.

Reference substance:

other: Sodium acetate

Parameter:

% degradation (CO2 evolution)

Value:

64

Sampling time:

28 d

Parameter:

% degradation (CO2 evolution)

Value:

62

Sampling time:

28 d

Details on results:

The final degradation value after the test period of 28 days was 63% (mean value of two parallel test solution). The toxicity control was degraded 44% within 14 days and showed that no toxicity of the test subtance has reduced the activity of the inoculum. The CO2 evolution measured in the blank was in the required range.

Table 1.  CO₂production and percentage biodegradation of the test substance (bottle A).

Day	HCl (0.05 N) titrated (mL)		Produced CO2 (mL HCl)	Produced CO2(mg)	Cumulative CO2(mg)	Biodegradation^1 (%)
	Blank (mean)	bottle A
2	48.03	47.83	0.20	0.2	0.2	0
5	47.41	43.45	3.96	4.4	4.6	5
7	47.57	43.13	4.44	4.9	9.4	11
9	47.26	41.71	5.55	6.1	15.6	18
14	45.79	38.18	7.61	8.4	23.9	27
19	44.09	36.84	7.25	8.0	31.9	37
23	44.17	36.68	7.49	8.2	40.1	46
27	45.07	38.64	6.43	7.1	47.2	54
29	46.25	41.63	4.62	5.1	52.3	60
29	48.67	45.98	2.69	3.0	55.2	63
29	49.96	49.58	0.38	0.4	55.7	64

¹⁾: Calculated as the ratio between CO₂produced (cumulative) and the ThCO₂of the test substance: 87.3 mg CO₂/2L

 

Table 2.  CO₂production and percentage biodegradation of the test substance (bottle B).

 

Day	HCl (0.05 N) titrated (mL)		Produced CO2 (mL HCl)	Produced CO2(mg)	Cumulative CO2(mg)	Biodegradation^1 (%)
	Blank (mean)	bottle B
2	48.03	47.53	0.49	0.5	0.5	1
5	47.41	43.33	4.08	4.5	5.0	6
7	47.57	43.30	4.27	4.7	9.7	11
9	47.26	42.60	4.66	5.1	14.9	17
14	45.79	38.10	7.69	8.5	23.3	27
19	44.09	37.19	6.90	7.6	30.9	35
23	44.17	36.82	7.35	8.1	39.0	44
27	45.07	38.40	6.67	7.3	46.3	53
29	46.25	41.47	4.78	5.3	51.6	59
29	48.67	46.30	2.37	2.6	54.2	62
29	49.96	50.00	0.00	0.0	54.2	62

¹⁾: Calculated as the ratio between CO₂produced (cumulative) and the ThCO₂of the test substance: 87.6 mg CO₂/2L

 

 

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

Reaction products of n-octanol and acrylic acid, first distillation pitch was readily biodegradability (62-64%).

Executive summary:

The test substance was tested for ready biodegradability according to OECD 301B Guideline, CO₂ evolution test (with GLP). Since the organic carbon content could not be calculated, a sample of the pure test substance was taken for determination of the Total Organic Carbon (TOC) content (to be 81%). Based on the TOC content the ThCO₂ was calculated to be 2.99 mg CO₂/mg.

The relative biodegradation values calculated from the measurements performed during the test period revealed 64 and 62% biodegradation of test substance, for A and B, respectively. Furthermore, the batch of Reaction products of n-octanol and acrylic acid, first distillation pitch is an UVCB and therefore the 10-day window was not applied.

In the toxicity control, test substance was found not to inhibit microbial activity. Since all criteria for acceptability of the test were met, this study was considered to be valid.

In conclusion, the test substance was designated as readily biodegradable.

Description of key information

Key study: OECD Guideline 301 B. GLP study. The aerobic biodegradation of test substance after 28 days of incubation attained 63% (mean) and was determined to be readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

Key study: Experimental result on test item Reaction products of n-octanol and acrylic acid, first distillation pitch:

The readily biodegradability in an aerobic aqueous medium with Carbon Dioxide (CO₂) evolution test (modified Sturm Test) was carried out according to the OECD Guideline 301B (GLP study). The aerobic biodegradation of test substance (14.6 mg/L) after 28 days of incubation with activated sludge (3.4 g/L SS) attained 63% (mean) based on CO₂ evolution. Therefore, the test substance was determined to be readily biodegradable in aerobic aqueous conditions.