2-[[4-[(2-cyanoethyl)ethylamino]phenyl]azo]-5-nitrobenzonitrile

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: inherent biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From January 11 to February 08, 1991

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study without detailed documentation

Qualifier:

equivalent or similar to guideline

Guideline:

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

GLP compliance:

not specified

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Details on inoculum:

- Inoculum: a mixed population of activated sewage sludge microorganisms.
- Source: the aeration Stage of Severn Trent PLC Sewage Treatment Plant, Belper, Derbyshire.
- Preparation: the activated sludge was maintained at a temperature of 21 ± 1 °C for 24 hours. The sludge was washed and settled repeatedly using dilution water prior to use.

Duration of test (contact time):

28 d

Initial conc.:

30 mg/L

Based on:

test mat.

Initial conc.:

78.6 mg/L

Based on:

ThOD

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Sludge usage rate: equivalent to 100 mg dry weight/l.
- Test temperature: 25 ± 1 °C
- Agitation: by magnetic stirrers.
- Continuous darkness: yes

SAMPLING
- Sampling frequency: manometric volumes were recorded daily.

PARAMETER MEASURED
A MITI (II) test was performed due to the low solubility of the test material in water. TOC analysis on the test material was not performed for this reason.
Theoretical Oxygen Demand (ThOD) was calculated to be 78.6 mgO2/l (2.62 mgO2/mg) assuming test material to be 100 % pure using the data supplied by the Sponsor.

Reference substance:

aniline

Remarks:

100 mg/l

Parameter:

% degradation (O2 consumption)

Value:

0 - 19

Sampling time:

28 d

Details on results:

Percentage degradation values were calculated by comparison of the oxygen uptake with Chemical Oxygen Demand.
Test item attained negligible degradation within 28 days calculated from oxygen uptake and so cannot, therefore be considered as inherently biodegradable under the strict terms and consitions of the OECD guideline.

A negligible degradation was also observed from comparison of the oxygen uptake values against ThOD. The variability in the degradation valves of the test material were the result of background variation of the oxygen uptake of the control vessels.

Results with reference substance:

Aniline attained 56 % biodegradation after 7 days and 70 % after 14 days thereby confirming the suitability of the inoculum and culture conditions. Total Organic Carbon (TOC) showed that aniline attained 94 % degradation, after 28 days.

Day	% biodegradation
	Test item	Aniline
1	4	1
2	10	4
3	6	10
4	15	21
5	0	46
6	6	52
7	0	56
8	19	58
9	0	61
10	16	66
11	13	67
12	14	70
13	15	68
14	0	70
15	7	68
16	14	71
17	0	73
18	0	72
19	0	74
20	14	76
21	7	75
22	0	70
23	0	79
24	0	82
25	0	85
26	14	85
27	0	85
28	0	79

All the biodegradability values have been corrected for blank values

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

The substance is not inherently biodegradable.

Executive summary:

A MITI (II) test was performed to investigate the biodegradability potential of the substance; the method was chosen due to the low solubility of the test material in water. TOC analysis on the test material was not performed for the same reason. Percentage degradation values were calculated by comparison of the oxygen uptake with Chemical Oxygen Demand.

Test item attained negligible degradation within 28 days (0 - 19 % over the whole experiment period) calculated from oxygen uptake, therefore, it cannot be considered as inherently biodegradable under the strict terms and consitions of the OECD guideline.

A negligible degradation was also observed from comparison of the oxygen uptake values against ThOD. The variability in the degradation valves of the test material were the result of background variation of the oxygen uptake of the control vessels.

Aniline attained 56 % biodegradation after 7 days and 70 % after 14 days thereby confirming the suitability of the inoculum and culture conditions. Total Organic Carbon (TOC) showed that aniline attained 94 % degradation, after 28 days.

Conclusion

The substance is not inherently biodegradable.

Description of key information

Neither readily nor inherently biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

A MITI (II) test was performed to investigate the biodegradability potential of the substance. Test item attained negligible degradation within 28 days (0 - 19 % over the whole experiment period) calculated from oxygen uptake, therefore, it cannot be considered as inherently biodegradable under the strict terms and consitions of the OECD guideline. A negligible degradation was also observed from comparison of the oxygen uptake values against ThOD.

[Type of water: freshwater]