4-(4-nitrophenylazo)-2,6-di-sec-butyl-phenol

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:

key study

Study period:

1992

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Although the study was conducted according to OECD TG 301B and EC Method C5 and in accordance with the Principles of Good laboratory Practices (GLP), additional biodegradation studies were not performed.

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to other 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.5 (Degradation: Biochemical Oxygen Demand)

Deviations:

no

Principles of method if other than guideline:

not applicable

GLP compliance:

yes

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
not applicable

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Details on inoculum:

The source of activated sludge obtained was from a municipal sewage treatment plant. The activated sludge was aerated for 4 hours and then left to settle for 1 hour. The supernatant was decanted to provide a sufficiently large volume for a 1% incolulum for each test flask.

Duration of test (contact time):

28 d

Initial conc.:

10 mg/L

Based on:

test mat.

Initial conc.:

20 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

Refer to attachments for more details

Reference substance:

other: sodium acetate

Preliminary study:

not applicable

Test performance:

The results were considered to be acceptable since the control substance degraded by at least 60% within 28 days and the total CO2 released in the blank at the end of the test was less than 50 mg CO2 per 3 litres medium.

Parameter:

% degradation (CO2 evolution)

Value:

21

Sampling time:

28 d

Remarks on result:

other: low concentration - 10 mg/l

Parameter:

% degradation (CO2 evolution)

Value:

13

Sampling time:

28 d

Remarks on result:

other: high concentration - 20 mg/l

Details on results:

The low concentration was 31.4 mg/l in 3 litre test medium and the high concentration was 63.4 mg/l in 3 litre test medium. Hence, the theoretical CO2 production following complete degradation would be 77.8 mg per 3 litre for the low and 157.2 mg per 3 litre for the high concentration.
The relative degradation values calculated from the measurements performed during the test period revealed significant biodegradation of Mortrace SB Conc. i.e. 21% at the low concentration (10 mg/l) and 13% at the high concentration (20 mg/l). As biodegradation was < 60% during the 28 days exposure period, Mortrace SB Conc. will not be considered 'readily biodegradable' under the conditions of the modified Strum test.

Results with reference substance:

The positive control contained 59.2 mg sodium acetate resulting in a theoretcoal CO2 production following complete degradation of 63.5 mg per 3 litre.

None

Validity criteria fulfilled:

yes

Interpretation of results:

other: not readily biodegradable

Conclusions:

As biodegradation was < 60% during the 28 days exposure period, Mortrace SB Conc. will not be considered 'readily biodegradable' under the conditions of the modified Strum test.

Executive summary:

Mortrace SB Conc. was tested for its ready biodegradability in the modified Strum test at nominal concentrations of 10 and 20 mg/l. The relative degradation values calculated from the measurements performed during the test period revealed significant biodegradation of Mortrace SB Conc. i.e. 21% at the low concentration (10 mg/l) and 13% at the high concentration (20 mg/l). As biodegradation was < 60% during the 28 days exposure period, Mortrace SB Conc. will not be considered 'readily biodegradable' under the conditions of the modified Strum test.

Reference 2

Endpoint:

biodegradation in water: inherent biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2007

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

The study was conducted in compliance with Good Laboratory Practice Standards and following the requirements of the OECD Guidelines for the Testing of Chemicals No. 302C Inherent Biodegradability: Modified MITI Test II (Adopted: 17th July 1992) and The Guidelines for the Testing of Chemicals, SEPA, P.R. China No. 302C Inherent Biodegradability: Modified MITI Test II (May 2004). There were no deviations from the related regulations that affected the quality or integrity of the study. The original report was written in Chinese and was translated to English. The full report is not available at this time. Information entered is from a condensed report for this study.

Qualifier:

according to guideline

Guideline:

OECD Guideline 302 C (Inherent Biodegradability: Modified MITI Test (II))

Deviations:

no

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Fresh samples were collected from ten sites, mainly in areas where a variety of chemicals were used and discharged. From sites such as sewage treatment works, industrial waste-water treatment works, rivers, lakes, seas.
- Laboratory culture: Collect 1 litre samples of sludge, surface soil, water, etc. and mix thoroughly together. After removing floating matter and allowing to stand, adjusted the supernatant to pH 7±1 with sodium hydroxide or phosphoric acid. Used an appropriate volume of the filtered supernatant to fill a fill-and-draw activated sludge vessel and aerated the liquid for about 23.5 hrs. Thirty minutes after stopping aeration, discarded about one third of the whole volume of supernatant and added an equal volume of a solution (pH 7) containing 0.1 % each of glucose, peptone and potassium orthophosphate, to the settled material and re-commence aeration. This procedure was repeated once per day.
- Storage conditions: Temperature was kept at 25 ± 2°C and at pH 7 ± 1, sludge was sufficiently aerated to keep the mixture aerobic at all times.
- Storage length: One month.
- Concentration of sludge: 100 ppm (W/V)

Duration of test (contact time):

28 d

Initial conc.:

30 other: ppm

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium:
The following stock solutions were prepared using analytical grade reagents:
Solution (a): 2 I .75 g of dipotassium hydrogen phosphate, 8.5 g of potassium acid phosphate, 44.6 g of dibasic sodium phosphate dodecahydrate and 1.7 g of ammonium chloride were dissolved in water and the volume was made up to 1000 ml (The pH of the solution was 7.2).
Solution (b): 22.5 g of magnesium sulphate heptahydrate were dissolved in water and the volume was made up to 1000 ml.
Solution (c): 27.5 g of calcium chloride was dissolved in water and the volume was made up to 1000 ml.
Solution (d): 0.25 g of ferric chloride hexahydrate was dissolved in water and the volume was made up to 1000 ml.

Preparation of Mineral Medium:
Took 3 ml of each solution (a), (b), (c) and (d), and made up to 1000 ml. (distilled water was used throughout).

- Solubilising agent (type and concentration if used): Distilled water
- Test temperature: 20°C
- Continuous darkness: yes


TEST SYSTEM
- Culturing apparatus: Normal laboratory equipment and especially the following were necessary: BOD-meter equipped with 6 bottles, pH-electrode and measuring equipment, bio-chemical incubator.
- Number of culture flasks/concentration: 6 bottles
- Method used to create aerobic conditions: Stirrers



SAMPLING
- Sampling frequency: Daily


CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes
- Abiotic sterile control: Yes

Reference substance:

aniline

Test performance:

Performance of the Test
Test vessel 1 contained 155.8 ml of deionized water, to which 4.71 mg of test substance was added; test vessels 1, 2 contained 155.8 ml of mineral medium, to which 4.71 mg of test substance was added; test vessel 3 contained 155.8 ml of mineral medium, to which 15.7 mg of aniline was added; test vessel 4 was for the control blank test, containing only 155.8 ml of mineral medium. Test vessels 1 and 2 (test suspensions), 3 (activity control) and 4 (inoculum blank) were with a small volume of the inoculum to give a concentration of 100 mg/l suspended solids. The equipment was assembled and checked that it was air-tight. The stirrers were started and the measurement of oxygen uptake under conditions of darkness was initiated. The temperature and stirrer was checked on a daily basis. The oxygen uptakes were read for the six bottles directly.

According to the criterion of OECD Guidelines for the Testing of Chemicals and The Guidelines for the Testing of Chemjcals, SEPA, P.R. China, the test was considered valid.

Parameter:

% degradation (O2 consumption)

Value:

55.9

Sampling time:

28 d

Details on results:

Treatment of Results:
Divided the oxygen uptake (mg) by the test substance (mg) after a given time, corrected for that taken up by the blank inoculum control after the same time, by the weight of the test substance used (mg). This yielded the BOD expressed as mg oxygen/mg test substance.

The percentage biodegradation was then obtained from:

% biodegradation = %ThOD = BOD (mg O2/mg substance)/ThOD (mg O2/mg substance) x 100

Results:
According to the calculation, the theoretic oxygen demanded of the test substance was 2.028 mg O2/mg test substance. The test results showed that, after 28 days test period finished, the percentage biodegradation of Marker 1 in activated sludge was 55.9%.

Parameter:

BOD5

Value:

0.7 mg O2/g test mat.

Results with reference substance:

The percentage degradation of aniline calculated from the oxygen consumption exceeded 40% after 7 days and 65% after 14 days.

Validity criteria fulfilled:

yes

Interpretation of results:

inherently biodegradable

Conclusions:

Based on the results and the grading criteria with regard to ecology toxicity in the Guidelines for the Hazard Evaluation of New Chemical Substances, State Environmental Protection Agency of P.R.C. (HJ/T 154-2004) test substance Marker 1 had inherent and primary degradability, owing to its percentage biodegradation which was 55.9%, more than 20%.

Executive summary:

The test assessed the inherent biodegradability of Marker 1 on micro-organisms in an aerobic aqueous medium by measuring its Biochemical Oxygen Demand (BOD). The test results showed that, after 28 days test period finished, the percentage biodegradation of Marker 1 in activated sludge was 55.9%.

Based on the result and the grading criteria with regard to ecology toxicity in the Guidelines for the Hazard Evaluation of New Chemical Substances, State Environmental Protection Agency of P.R.C. (HJ/T 154-2004) the test substance, Marker 1, was concluded that it had inherent and primary degradability, owing to its percentage biodegradation which was 55.9%, more than 20%.

Description of key information

As biodegradation was < 60% during the 28 days exposure period, Mortrace SB Conc. is not be considered 'readily biodegradable' under the conditions of the modified Strum test. However, Mortrace SB Conc. is considered inherently biodegradable based on the results of the modified Miti Test.

Key value for chemical safety assessment

Biodegradation in water:

inherently biodegradable, fulfilling specific criteria

Additional information

Mortrace SB Conc. was assessed for biodegradability in two, valid biodegradability tests. In one test, the ready biodegradability of the test material was assessed via the modified Strum test (OECD 301B) at nominal concentrations of 10 and 20 mg/l. The relative degradation values calculated from the measurements performed during the test period revealed significant biodegradation of Mortrace SB Conc. i.e. 21% at the low concentration (10 mg/L) and 13% at the high concentration (20 mg/L). As biodegradation was < 60% during the 28 days exposure period, Mortrace SB Conc. is not considered 'readily biodegradable' under the conditions of the modified Strum test. In a second biodegradation test, Mortrace SB Conc. was evaluated for inherent biodegradation in the Modified Miti Test (OECD 302C). Based on the observation of 55.9% biodegradability, the test substance is considered inherently biodegradable.