Phosphoric acid, butyl ester, sodium salt

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

from 2007-02-22 to 2007-05-30

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)

Deviations:

no

GLP compliance:

no

Remarks:

The study was conducted in accordance with ISO/IEC 17025.

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: Activated sludge from the aeration tank of a municipal biological waste water treatment plant, not adapted, not pre-conditioned. ARA Werdhölzli, CH-8048 Zürich, Switzerland, 28 March 2007, 11.00 a.m.
- Concentration of sludge: 30 mg/L suspended solids

Duration of test (contact time):

28 d

Initial conc.:

50.3 mg/L

Based on:

test mat.

Initial conc.:

37.7 other: COD/L

Based on:

COD

Parameter followed for biodegradation estimation:

DOC removal

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

- Test units: 500 mL glass bottles (tightly closed with manometric BOD measuring devices) containing a total volume of test solution of 200 mL. The bottles
are equipped with stirring rods and butyl rubber quivers which contain 2 pellets of sodium hydroxide each to absorb the produced CO2 from the head space.
- Test temperature: 22 ± 0.5 °C
- Medium: Aerobic mineral salts medium prepared with deionised water. Staedard medium prepared according to OECD 301
- Feeding: no feeding took place during the test
- Suspended solids concentration: 30 mg/L
- Continuous darkness: yes

Reference substance:

benzoic acid, sodium salt

Remarks:

50 mg/L (ThOD 83.3 mg/L)

Key result

Parameter:

% degradation (O2 consumption)

Value:

85

Sampling time:

28 d

Key result

Parameter:

% degradation (DOC removal)

Value:

94

Sampling time:

28 d

Details on results:

The calculated biodegradation based on DOC measurement reached 94 % for the test item and 100 % for sodium benzoate. The data show that the consumed O2 was used for partial mineralisation of the test compound, since the determined degradation values based on BOD were lower as compared to those based on DOC.
The respective DOC concentrations at the beginning and at the end of the test (after 28 days) were (in mg/L):
9.05 and 1.26 for the test units (mean of 2 replicates)
<0.5 and 0.74 for the inoculum blank (mean of 2 replicates)
29.2 and 1.26 for the procedure control (one replicate)

Results with reference substance:

The procedure control sodium benzoate reached 82 % biodegradation after 14 days, thus, confirming suitability of inoculum and test conditions.

Table 1: O2 uptake of the test units, the inoculum blank, the procedure control and the corresponding degradation data.

	Inoculum Blank *	Test unit no. 1 with test item		Test unit no. 2 with test item			Procedure control (sodium benzoate)
Time (days)	BOD (mg O2/L)	BOD (mg O2/L)	Degradation (%) **	BOD (mg O2/L)	Degradation (%) **	Mean Degradation of no. 1+2 (%)	BOD (mg O2/L)	Degradation (%) ***
0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
1	9.0	10.0	2.7	6.0	-8.0	-2.7	26.0	20.4
2	13.0	12.0	-2.7	12.0	-2.7	-2.7	38.0	30.0
3	15.0	16.0	2.7	14.0	-2.7	0.0	47.0	38.4
4	18.0	28.0	26.5	20.0	5.3	15.9	58.9	49.1
5	20.0	38.0	47.7	24.0	10.6	39.2	68.9	58.7
6	22.0	42.0	53.0	28.0	15.9	34.5	73.9	62.3
7	21.0	40.0	50.4	32.0	29.2	39.8	74.9	64.7
8	26.0	46.0	53.0	36.0	26.5	39.8	81.9	64.7
9	26.0	50.0	63.6	40.0	37.1	50.4	85.9	72.0
10	27.0	52.0	66.3	46.0	50.4	58.3	88.9	74.4
11	28.0	53.9	68.7	50.0	58.3	63.5	90.9	75.6
12	29.0	55.9	71.3	53.9	66.0	68.7	93.9	78.0
13	30.0	59.9	79.3	55.9	68.7	74.0	95.9	79.2
14	30.0	59.9	79.3	59.9	79.3	79.3	97.9	81.6
15	31.0	59.9	76.6	59.9	76.6	76.6	100.0	82.8
16	31.0	61.9	81.9	59.9	76.6	79.3	101.0	84.0
17	33.0	61.9	76.6	61.9	76.6	76.6	102.0	82.8
18	32.0	63.9	84.6	61.9	79.3	81.9	104.0	86.5
19	33.0	63.9	81.9	63.9	81.9	81.9	105.0	86.5
20	33.0	63.9	81.9	65.9	87.2	84.6	106.0	87.7
21	34.0	65.9	84.6	65.9	84.6	84.6	107.0	87.7
22	34.0	65.9	84.6	63.9	79.3	81.9	108.0	88.9
23	35.0	65.9	81.9	65.9	81.9	81.9	108.0	87.7
24	35.0	65.9	81.9	65.9	81.9	81.9	109.0	88.9
25	35.0	65.9	81.9	67.9	87.2	84.6	109.0	88.9
26	35.0	67.9	87.2	65.9	81.9	84.6	110.0	90.1
27	35.0	67.9	87.2	65.9	81.9	84.6	111.0	91.3
28	37.0	69.9	87.2	67.9	81.9	84.6	112.0	90.1

 

*            Mean of two replicates

**         The calculation is based on the nominal concentration of the test substance of 50.3 mg/L and a chemical O2 demand (COD) in mg O2/mg test substance of 0.750. The applied COD in the vessels in mg O2/L was 37.7.

***       The calculation is based on the nominal concentration of sodium benzoate of 50.0 mg/L and a chemical O2 demand (COD) in mg O2/mg test substance of 1.665.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The test item reached the pass level of 60 % for ready biodegradability in the Manometric Respirometry Test within the 10-d window and, therefore, can be classified as readily biodegradable.

Executive summary:

The ready biodegradability of the test item was determined with a non-adapted activated sludge over a test period of 28 days in the Manometric Respirometry test according to OECD 301F and Regulation (EC) No. 440/2008 Method C.4-D. The test item was tested at a concentration of 50.3 mg/L in two replicates, corresponding to an oxygen content of 37.7 mg O2/L. The biodegradation of the test item came to 94 % after 28 days based on the COD of the test item and 85 % based on the O2 consumption. The data show that the consumed O2 was used for partial mineralisation of the test compound, since the determined degradation values based on BOD were lower as compared to those based on DOC. In conclusion, the test item is readily biodegradable as the pass level of 60 % degradation was reached in a 10-d-window within the 28 days period of the study.

Reference 2

Endpoint:

biodegradation in water: inherent biodegradability

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

from 2007-02-22 to 2017-05-30

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Qualifier:

according to guideline

Guideline:

OECD Guideline 302 B (Inherent biodegradability: Zahn-Wellens/EMPA Test)

Deviations:

no

GLP compliance:

no

Remarks:

The study was conducted in accordance with ISO/lEC 17025. BMG

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: Activated sludge from the aeration tank of a municipal biological waste water treatment plant, not adapted, not pre-conditioned. ARA Werdhölzli, CH-8048 Zürich, Switzerland. 26 February 2007, 9.30 a.m.
- Concentration of sludge: 0.2 g/L dry matter in the final mixture
The activated sludge was used immediately after sampling from the treatment plant without adaptation. Prior to the test the sludge was washed twice with tap water.

Duration of test (contact time):

28 d

Initial conc.:

284 mg/L

Based on:

test mat.

Initial conc.:

48.3 mg/L

Based on:

DOC

Reference substance:

diethylene glycol

Remarks:

48.4 mg/L (as DOC)

Key result

Parameter:

% degradation (DOC removal)

Value:

95

Sampling time:

28 d

Details on results:

Based on the data of the individual DOC determinations the test item reached a biodegradation of 95 % after 28 days. The main degradation process occurred during the first 4 days, when more than 90 % of the initial DOC was removed. Maximum biodegradation was attained after 18 days of incubation. No significant
adaptation period (lag phase) was observed.

Results with reference substance:

The positive control, diethyleneglycol, showed 99 % biodegradation after 14 days of incubation, thus, confirming suitabilis of inoculum and test conditions. The test was considered valid, since the degradation of the reference compound reached more than 70 % within 14 days of incubation.

No significant elimination of the test substance due to adsorption to the activated sludge, on the glass surface or other physico-chemical processes was found as determined by means of DOC measurements 3 h after the start of the test.

Table 1: DOC concentrations of test suspension, inoculum blank and procedure control and calculation of degradation data.

	Inoculum blank (B)*	Procedure control – diethylene glycol (R)			Test suspension with test item (T)*
Time (days)	DOC (mg/L)	DOC (mg/L)	DOC net. (mg/L)	Degradation (%)	DOC (mg/L)	DOC net. (mg/L)	Degradation (%)
0	0.7	49.6	48.9	-	49.6	48.9	-
0.125	0.7	50.1	49.4	0	46.1	45.4	0
1	1.2	46.0	44.8	9	45.1	43.9	3
4	1.3	28.3	27.0	45	4.8	3.5	92
7	1.6	1.9	0.3	99	4.3	2.7	94
11	2.5	2.6	0.1	100	5.3	2.8	94
14	2.2	2.7	0.5	99	5.2	3.0	93
18	2.1	2.3	0.2	100	4.5	2.4	95
21	2.2	2.2	0.0	100	4.7	2.5	94
25	2.3	2.2	-0.1	100	5.6	3.3	93
27	1.7	2.2	0.5	99	4.4	2.7	94
28	1.9	2.0	0.1	100	4.1	2.2	95

* Mean of two replicates

The biodegradation of the test item based on CO2 evolution and calculated as % ThCO2 reached 50 % after 28 days, showing that the main part of the organic carbon of the test material was transformed into CO2. The extent of mineralization of the reference compound diethylene glycol was within the same range showing a value of 95 % based on ThCO2.

Table 2: IC concentrations, calculated from the concentrations in the gas absorption bottles of test suspension, inoculum blank and procedure control and corresponding degradation data.

Time (days)	Test suspension IC (mg/L)	Procedure control IC (mg/L)	Inoculum blank IC (mg/L)	Biodegradation Test suspension (% ThCO2)	Biodegradation Procedure control (% ThCO2)
0 7 14 21 28	nd 39.0 63.6 70.7 72.9	nd 56.7 76.6 89.5 95.0	nd 21.1 34.4 44.4 48.9	- 37 60 55 50	- 74 87 93 95

nd         not determined

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

Based on these results the test item can be classified as ultimately biodegradable under the conditions of the test, since more than 70 % degradation was attained after 28 days of contact time.

Executive summary:

The inherent biodegradability of the test item was determined with a non-adapted activated sludge over a test period of 28 days in the Zahn-Wellens test according to OECD 302B. The test item was tested at a concentration of 284 mg/L in two replicates, corresponding to a DOC content of 48.3 mg/L. The biodegradation of the test item came to 95 % after 28 days based on the DOC removal. The main degradation process occurred during the first 4 days, when more than 90 % of the initial DOC was removed. Maximum biodegradation was attained after 18 days of incubation. No significant adaptation period (lag phase) was observed. In conclusion, the test item is ultimately biodegradable since more than 70 % degradation was attained after 28 days of contact time.

Description of key information

The biodegradability of the test item was tested under different test conditions. All tests showed that the test item is readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

Manometric Respirometry Test

The ready biodegradability of the test item was determined with a non-adapted activated sludge over a test period of 28 days in the Manometric Respirometry test according to OECD 301F and Regulation (EC) No. 440/2008 Method C.4-D. The test item was tested at a concentration of 50.3 mg/L in two replicates, corresponding to an oxygen content of 37.7 mg O2/L. The biodegradation of the test item came to 94 % after 28 days based on the COD of the test item and 85 % based on the O2 consumption.The data show that the consumed O2 was used for partial mineralisation of the test compound, since the determined degradation values based on BOD were lower as compared to those based on DOC.In conclusion, the test item is readily biodegradable as the pass level of 60 % degradation was reached in a 10-d-window within the 28 days period of the study.

Zahn-Wellens Test

The inherent biodegradability of the test item was determined with a non-adapted activated sludge over a test period of 28 days in the Zahn-Wellens test according to OECD 302B. The test item was tested at a concentration of 284 mg/L in two replicates, corresponding to a DOC content of 48.3 mg/L. The biodegradation of the test item came to 95 % after 28 days based on the DOC removal.The main degradation process occurred during the first 4 days, when more than 90 % of the initial DOC was removed. Maximum biodegradation was attained after 18 days of incubation. No significant adaptation period (lag phase) was observed.In conclusion, the test item is ultimately biodegradable since more than 70 % degradation was attained after 28 days of contact time.

Static Method Test

A study following the static method was performed to determined the biological elimination of the test item by means of TOC removal. The test item was tested at concentration of 1400 mg/L corresponding to 400 mg/L TOC. The test was performed for 14 days. After 3 h the TOC remal was 12 % and at the end of the exposure period, 14 days, was 77 %. The test item can be considered as readily biodegradable as it attained more than 70 % degradation in 14 days.