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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: Meets the criteria for classification as Reliable without restriction according to Klimisch et al (1997)

Data source

Reference Type:
study report

Materials and methods

Test guideline
according to guideline
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
GLP compliance:

Test material

Constituent 1
Chemical structure
Reference substance name:
EC Number:
EC Name:
Cas Number:
Molecular formula:
C35H31N8O18S3.xNa.yK, where x+y=3
dipotassium sodium 3-[(1E)-2-{4-[(1E)-2-{4-[(1E)-2-(5-carbamoyl-1-ethyl-2-hydroxy-4-methyl-6-oxo-1,6-dihydropyridin-3-yl)diazen-1-yl]-2-sulfonatophenyl}diazen-1-yl]-2,5-bis(2-hydroxyethoxy)phenyl}diazen-1-yl]-4,5-dihydroxynaphthalene-2,7-disulfonate

Study design

Oxygen conditions:
Inoculum or test system:
activated sludge, domestic (adaptation not specified)
Details on inoculum:
Activated sludge was obtained from Buckland Sewage Treatment Works, Newton Abbot, Devon, UK on 11 February 2004. This works treats sewage of predominantly domestic origin. At the laboratory, the activated sludge was kept aerated at room temperature.
Duration of test (contact time):
28 d
Details on study design:
The experimental design consisted of two types of control. The inoculum blanks contained viable organisms with no test or reference substance, the purpose of which was to demonstrate that there was no other carbon source in the test medium. The toxicity controls, comprised a mixture of test substance and sodium acetate, at nominal 100 and 200 mg/l, respectively. In the event that the test substance failed to degrade during the 28 day test period, the purpose of the toxicity control was to indicate whether the failure might have been caused by the test substance inhibiting bacterial activity in the inoculum.

The units containing test susbstance were dosed from a primary stock solution containing 1000 mg/l of test substance in deionised water prepared on the exposure start day. Oxygen uptake was recorded on weekdays during the 28 day experimental period. Oxygen uptake values were corrected for the inoculum blank. The biodegradation was calculated as a percentage of the measured chemical oxygen demand for the test or reference substance, as appropriate.

The pH of the test medium prior to use was measured and adjusted as necessary to 7.4 ± 0.2. The pH in all the bottles once prepared was measured and adjusted to 7.4 ± 0.2, if necessary. The pH in all of the test bottles was measured on day 28. The study was performed in a constant temperature room to maintain the test bottle temperatures within the nominal range of22 ± 2°C.
Reference substance
Reference substance:
other: Sodium Acetate

Results and discussion

Preliminary study:
None conducted
Test performance:
The results for the reference substance indicate that the test system was operating as expected.
% Degradationopen allclose all
% degradation (O2 consumption)
< 10
Sampling time:
6 d
% degradation (O2 consumption)
< 12
Sampling time:
10 d
% degradation (O2 consumption)
< 7
Sampling time:
15 d
% degradation (O2 consumption)
< 5
Sampling time:
21 d
% degradation (O2 consumption)
< 5
Sampling time:
28 d

BOD5 / COD results

Results with reference substance:
Points of degradation plot (reference substance):
68 % degradation after 5 d
71 % degradation after 10 d
67 % degradation after 15 d
59 % degradation after 20 d
52 % degradation after 28 d

Any other information on results incl. tables

The COD of the test substance was determined as 0.96 g O2/g and the BOD values after 6 and 28 days were 0.10 and 
0.05g O2/g respectively. The percentage degradation was calculated as (BOD/COD) X 100.

The measured COD value of sodium acetate was 0.78 g 02 g/1 of substance. Although this was higher than the value of approximately 0.68 g O2 gol usually obtained, it was identical to the theoretical oxygen demand. Since a high measured COD requires a higher BOD to achieve the criterion of >60% biodegradation within the 10 day window, this measured COD was considered satisfactory.

Applicant's summary and conclusion

Validity criteria fulfilled:
Interpretation of results:
other: not readily biodegradable
Based on the results of the test, the test substance is considered to be not readily biodegradable. Given the structure of the test material this result is not unexpected.