Reaction products of disodium 3,5-diamino-2-[(2-sulfonatophenyl)diazenyl]benzoate and  diazotised sodium 2-[(4-aminophenyl)sulfonyl]ethyl sulfate

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:

Study initiation date - 10 January 2003; Experiment start date - 13 January 2003; Experiment completion date - 11 February 2003; Study completion date - 11 March 2003.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 A (Ready Biodegradability: DOC Die Away Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.4-A (Determination of the "Ready" Biodegradability - Dissolved Organic Carbon (DOC) Die-Away Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Identity: FAT 40810/A
Batch: WP 6/02
Purity: approx. 75 %
Appearance: Solid, dark brownish powder
Expiration date: 12 December 2010
Storage: At room temperature at about 20 °C

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

Strain / Inoculation: Mixture of polyvalent bacteria (activated sludge) collected on January 13 from the aeration tank of a domestic sewage treatment plant, ARA Pro Rheno Basel communal.

Sludge pre-treatment: The activated sludge was washed 4 times with tap water and the last time with test medium. A sample of the activated sludge was taken to determine the dry weight of the Suspended Solids (SS). An amount corresponding to 2 - 3 g per litre of suspended solids was mixed with test medium. The pre-treated sludge was aerated until use. The pH value of the activated sludge was 7.1.
Bacteria concentration: 30 mg/L suspended solids; the bacteria concentration was obtained by adding 5 mL of the pre-treated sludge (3.0 g/L SS) per 500 mL test medium.

Duration of test (contact time):

28 d

Initial conc.:

36.9 mg/L

Based on:

DOC

Parameter followed for biodegradation estimation:

DOC removal

Details on study design:

For each test series the following number of test vessels was set up:
Test item: 2 vessels with inoculum + test medium + test item
Inoculum control: 2 vessels with inoculum + test medium
Procedure control: 2 vessels with inoculum + test medium + a readily biodegradable reference compound
Abiotic Sterile Control: 1 vessel with test medium + test item without inoculum, sterilised by ultra-filtration (Gelman Vacucap 0.2 µm, sterilised)
Inhibition control: 1vessel with inoculum + test medium + test item +reference compound
A measured volume of inoculated mineral medium, containing a known concentration of the test item as the nominal source of organic carbon, was aerated in the darkness at 22 ± 2 °C nominal. The degradation was followed by DOC analysis at frequent intervals over a period of 28 days. The degree of biodegradation was calculated by expressing the concentration of DOC removed (corrected by the blank inoculum control) as a percentage of the concentration initially added.

Reference substance:

other: D(+)-Glucose

Test performance:

The test was considered valid because:
the difference of extremes values of the removal of the test chemical at the plateau, at the end of the test or at the end of the 10-day window was less than 20 %;
the degradation of the reference item at day 14 reached the pass level of 70 %;
the degradation of the inhibitory action at day 14 was ≥ 35 %;
the abiotic degradation of the sterile control at day 28 was not >10 %;

Parameter:

% degradation (DOC removal)

Value:

2

Sampling time:

28 d

Details on results:

Points of degradation plot (test substance): 3 % degradation after 1 d, 4 % degradation after 7 d, 2 % degradation after 10 d, 6 % degradation after 14 d, 3 % degradation after 21 d, 2 % degradation after 28 d.

Results with reference substance:

Points of degradation plot (reference substance):
42 % degradation after 1 d
94 % degradation after 7 d
93 % degradation after 10 d
97 % degradation after 14 d
95 % degradation after 21 d
96 % degradation after 28 d

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

The biodegradation of FAT 40810/A was determined as 2 % after 28 days of incubation. FAT 40810/A is concluded to be not readily biodegradable.

Executive summary:

The objective of this study was to determine the Ready Biodegradability of FAT 40810/A under aerobic static exposure conditions using the DOC Die - Away Test. In this method, a low concentration of bacterial inoculum (≤ 30 mg/L of suspended solids) derived from the activated sludge of a sewage plant, mineral nutrients and a known concentration of the test item (10 - 40 mg/L DOC) as the nominal sole source of organic carbon were aerated in the dark at 22 ± 2 °C over a 28-d period. Inoculation Mixture of polyvalent bacteria (activated  sludge) was collected as test organism. Based on the findings of the study, the biodegradation of FAT 40810/A was determined as 2 % after 28 days of incubation. FAT 40810/A is concluded to be not readily biodegradable.

Description of key information

The biodegradation of the substance was determined as 2 % after 28 days of incubation. The test substance did not reach the pass level of 70 % for ready biodegradability in the DOC Die-Away Test either within the 10-day window or after 28 days of incubation. Therefore, the substance cannot be assessed as readily biodegradable. Under Inherent biodegradability test conditions, the total elimination (regarding biodegradation) of the substance after 28 days was 13 %. The substance is though considered not inherently biodegradable. Also, the Biochemical Oxygen Demand experiment gave a BOD₅ value of 0 mg O₂/g, and therefore the substance is not considered as biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

not biodegradable

Type of water:

freshwater