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Environmental fate & pathways

Biodegradation in water: screening tests

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Administrative data

biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Guideline study. Validy criteria fulfilled

Data source

Reference Type:
study report
Report date:

Materials and methods

Test guidelineopen allclose all
according to guideline
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Version / remarks:
(Modified Sturm Test)
according to guideline
EU Method C.5 (Degradation: Biochemical Oxygen Demand)
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Reference substance name:
Details on test material:
- Name of test material (as cited in study report): RXSS/91/404; N,N'-Bis(3-methylphenyl)-N,N'-diphenyl-(1,1'-biphenyl)-4,4'diamine
- Physical state: white powder
- Analytical purity: 99.66%
- Lot/batch No.: 011G

Study design

Oxygen conditions:
Inoculum or test system:
activated sludge, domestic (adaptation not specified)
Details on inoculum:
- source of inoculum: the aeration stage of the Severn Trent Plc sewage treatment plant at Belper, Derbyshire, treating predominantly domestic sewage
- Preparation of inoculum for exposure: activated sludge was homogenised for 10 min. The solids were settled and the supernatant filterd through Whatman GFA paper prior to testing.
- Concentration of sludge: usage rate = 1% inoculum
Duration of test (contact time):
28 d
Initial test substance concentrationopen allclose all
Initial conc.:
10 mg/L
Based on:
test mat.
Initial conc.:
20 mg/L
Based on:
test mat.
Details on study design:
- Test temperature: 21 +/- 1°C
- Aeration of dilution water: CO2-free air bubbled through solution (2 bubbles per second)
- stirring: continuously by magnetic stirrers
- Continuous darkness: yes

- Culturing apparatus: 5 L glass culture vessels, containing 3 L

- Sampling frequency: first absorber at days 0, 1, 2, 3, 6, 8, 10, 14, 16, 21, 23, 27 and 28. Second absorber at days 0 and 28.
- Sampling method: CO2 absorption in 2 Dreschel bottles, 350 mL 0.05 M NaOH
On day 27 pH of each vessel was measured, and 1 mL concentrated HCl added to drive off inorganic carbonate. The vessels were aerated overnight and the final samples were taken from both absorber vessels on day 28.

- Inoculum blank: yes
Reference substance
Reference substance:
benzoic acid, sodium salt

Results and discussion

% Degradation
% degradation (CO2 evolution)
Sampling time:
28 d
Remarks on result:
other: both at 10 and 20 mg/L
Details on results:
Points of degradation plot (test substance):
0 % degradation after 1 d
0 % degradation after 2 d
1 % degradation after 3 d
0 % degradation after 6 d
0 % degradation after 8 d
0 % degradation after 10 d
0 % degradation after 14 d
0 % degradation after 16 d
0 % degradation after 21 d
2 % degradation after 23 d

BOD5 / COD results

Results with reference substance:
Points of degradation plot (reference substance):
1 % degradation after 1 d
5 % degradation after 2 d
9 % degradation after 3 d
31 % degradation after 6 d
48 % degradation after 8 d
60 % degradation after 10 d
82 % degradation after 14 d
94 % degradation after 16 d
90 % degradation after 21 d
89 % degradation after 23 d

Applicant's summary and conclusion

Validity criteria fulfilled:
Interpretation of results:
other: not readily biodegradable
Test substance cannot be considered as ready biodegradable under the conditions of this test. However, testing was performed above water solubilitylevel.
Executive summary:

Biodegradation of N,N'-Bis(3-methylphenyl)-N,N'-diphenyl-(1,1'-biphenyl)-4,4'diamine was tested according to OECD 301 B (CO2 -evolution, modified Sturm Test)/ EU-Method C.3 over 28d using activated sludge as an inoculum. Tested concentrations were 10 mg/L and 20 mg/L which were above water solubility level. 3% biodegradation was observed after 28d. Under this conditions the test substance is regarded as not readily biodegradable.