p-nitrobenzoic acid, compound with 2,2',2''-nitrilotriethanol (1:1)

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:

20 September 2001 - 18 October 2001

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Non-GLP but documented in detail. Further details on test item not reported.

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

1992

Deviations:

yes

Remarks:

The test procedure was conducted as described in detail in BMG's Standard Operating Procedure (Standardarbeitsanweisung BMG-1028).

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

1992

Deviations:

yes

Remarks:

The test procedure was conducted as described in detail in BMG's Standard Operating Procedure (Standardarbeitsanweisung BMG-1028).

Principles of method if other than guideline:

Alteration of the standard procedure: At the end of the test the pH value of both inoculum blanks and the procedure control was 7.2 and 6.6, respectively. The pH value of both test suspensions was 6.5, respectively.

GLP compliance:

no

Remarks:

The study was conducted in accordance with SN EN 45001

Specific details on test material used for the study:

The test material was a 65 % solution in water.

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Activated sludge from the aeration tank of a municipal biological waste water treatment plant, ARA Werdhölzli, CH-8048, Zürich,19 September 2001; 9:30 a.m.

- Storage length: No storage. Used immediately after sampling
- Pretreatment: not adapted, not pre-conditioned
- Concentration of sludge: 30 mg/l dry matter in the final mixture
- Test Medium: Aerobic mineral salts medium prepared with deionised water (details on medium available in report)

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

test mat.

Remarks:

Nominal

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: Mineral salts medium. See table on Any other information on materials and methods section
- Additional substrate: none
- Solubilising agent: none
- Test temperature: 22 +/- 0.5 °C
- pH: 7.4 +/- 0.2
- pH adjusted: yes, with NaOH or H2SO4, if necessary.
- Aeration of dilution water: no
- Continuous darkness: yes

TEST SYSTEM
- Test units: 1200 ml closed glass bottle (tightly closed with a butyl rubber stopper) containing a total volume of test solution of 400 ml
- Number of culture flasks: 2 flasks with test suspension
- Test vessels were agitated on an orbital shaker (100 r.p.m.)

SAMPLING
- Sampling frequency: after 1 day and then at regular intervals of 4 days
- Sampling method: 0.2 ml headspace samplig with gas syringe
- Sample storage before analysis: no, direct injection to GC

CONTROL AND BLANK SYSTEM
- Inoculum blank: 2 replicates containing inoculum and test medium
- Abiotic sterile control: 1 replicate containing test substance, test medium and 0.2 mM HgCl as sterilizing agent
- Toxicity control: 1 replicate inoculum + test medium + test substance + sodium benzoate as ready biodegradable reference compound
- Procedure control: 1 replicate containing inoculum, test medium and sodium benzoate as ready biodegradable reference compound

STATISTICAL METHODS:
Values of % degradation were calculated for each sample from the test suspension and the procedure control. The arithmetic mean of % degradation in each test flask was calculated.

Reference substance:

benzoic acid, sodium salt

Test performance:

The positive control, sodium benzoate, reached 90 % biodegradation after 14 days, thus confirming suitability of inoculum and test conditions.
The ThOD of the reference compound sodium benzoate was calculated to be 1.665 mg O2/mg substance.

Key result

Parameter:

% degradation (O2 consumption)

Value:

ca. 90

Sampling time:

28 d

Remarks on result:

other: mean of two replicate flasks

Parameter:

% degradation (O2 consumption)

Value:

ca. 80

Sampling time:

11 d

Remarks on result:

other: mean of two replicate flasks

Details on results:

Significant biodegradation of the test substance was observed after a lag phase of about 1 day.
The respective DOC concentrations at the beginning and at the end of the test (after 28 days) were (in mg/l):
31.8 and 1.13 for the test units (mean of two replicates)
0.30 and 1.18 for the inoculum blank (mean of two replicates)
57.5 and 1.46 for the procedure control (one replicate)
The calculated biodegradation based on DOC measurement reached 99 % for REVATOL NS and for sodium benzoate. The data show that the consumed O2, was used for complete mineralization of the test compound, since the determined degradation values based on BOD were within the same range than those based on DOC.

Table: O2 concentration (mg O2 per test sample) of the test units, the procedure, toxicity and the abiotic sterile control and the inoculum blank.

Time (days)	Test Unit N1	Test unit N2	Toxicity control	Abiotic sterile control	Inoculim blank (mean of 2 replicates)	Procedure control
0	244.0	244.0	n.d.	n.d.	244.0	244.0
4	241.7	241.0	n.d.	n.d.	242.2	225.9
7	211 .3	206.8	n.d.	n.d.	235.4	185.6
11	199.5	204.4	n.d.	n.d.	237.7	180.6
14	197.2	201.0	n.d.	n.d.	235.2	175.3
18	194.1	196.0	n.d.	n.d.	234.6	174.2
21	194.9	193.0	n.d.	n.d.	233.5	173.2
25	194.3	191.6	n.d.	n.d.	232.3	171.5
28	191 .8	188.8	n.d.	n.d.	230.4	169.6

Validity criteria fulfilled:

not specified

Remarks:

The positive control, sodium benzoate, reached 90% biodegradation after 14 days, thus confirming suitability of inoculum and test conditions.

Interpretation of results:

readily biodegradable

Conclusions:

In this study according to OECD 301 F, the test material reached a biodegradation of 90%. It reached the pass level of 60 % for ready biodegradability in the Manometric Respirometry Test within the 10-d window and, therefore, can be termed as readily biodegradable.

Executive summary:

The biodegradability of the test material exposed to microorganisms derived from activated sludge of a municipal sewage treatment plant was investigated under aerobic static exposure conditions.

The biodegradability of the test material based on O2 consumption was calculated to be 90 % after 28 days as compared to the theoretical O2 demand (ThOD).

The biodegradation of the test material reached 80 % at the end of the 10-d window.

Significant biodegradation of the test substance was observed after a lag phase of about 1 day.

The procedure control sodium benzoate reached 90 % biodegradation after 14 days, thus confirming suitability of inoculum and test conditions.

The calculated biodegradation based on DOC measurement reached 100 % for the test material and for sodium benzoate. The data show that the consumed O2 was used for complete mineralization of the test compound, since the determined degradation values based on BOD were within the same range than those based on DOC.

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

Description of key information

A study according to OECD 301F with the substance (65 % solution in water) was available. It is a non-GLP study but documented in detail. Further details on the test item were not reported. The study is rated Klimisch 2.

 

The biodegradability of the test material based on O2 consumption was calculated to be 90 % after 28 days as compared to the theoretical O2 demand (ThOD).

The biodegradation of the test material reached 80 % at the end of the 10-d window.

The calculated biodegradation based on DOC measurement reached 100 % for the test material and for sodium benzoate. The data show that the consumed O2 was used for complete mineralization of the test compound, since the determined degradation values based on BOD were within the same range than those based on DOC.

 

The active ingredient of the test material is p-Nitrobenzoic acid, compound with 2,2',2''-nitrilotriethanol (1:1).

Therefore the results with the test material are applicable to the substance p-Nitrobenzoic acid, compound with 2,2',2''-nitrilotriethanol (1:1) CAS no. 7394-38-9.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater