N-(2-chloroethyl)-4-[(2,6-dichloro-4-nitrophenyl)azo]-N-ethyl-m-toluidine

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

Deviations:

yes

Remarks:

The study integrity was not adversely affected by these deviations.

Principles of method if other than guideline:

Since Disperse Brown 27 was not sufficiently soluble to allow preparation of an aqueoussolution at a concentration of 1 g/L, weighed amounts were added to the 2-litres test bottles containing medium with microbial organisms and mineral components. To this end, 10 mL of Milli-RO water was added to each weighing bottle containing the test item. After vigorous mixing (vortex) the resulting suspension was added quantitatively to the test medium. The test solutions were continuously stirred during the test to ensure optimal contact between the test item and test organisms. Furthermore, the test medium was daily swirled around, since the test item tended to float on the water surface. Test duration was 28 days (last CO2- measurement on day 29).

GLP compliance:

yes

Specific details on test material used for the study:

The batch of Disperse Brown 27 (4852-1501) tested was a brown powder with a purity of 99.7 %

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Duration of test (contact time):

ca. 28 d

Initial conc.:

ca. 24.5 mg/L

Based on:

test mat.

Initial conc.:

ca. 12 mg/L

Based on:

TOC

Parameter followed for biodegradation estimation:

CO2 evolution

Reference substance:

acetic acid, sodium salt

Key result

Parameter:

% degradation (CO2 evolution)

Value:

>= 0 - <= 7

Sampling time:

28 d

Details on results:

Disperse Brown 27 was not readily biodegradable under the conditions of the modified Sturm test presently performed.

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

Disperse Brown 27 was not readily biodegradable under the conditions of the modified Sturm test presently performed.

Executive summary:

Disperse Brown 27 was a brown powder with a purity of 99.7% (HPLC). The test item was tested in duplicate at a target concentration of 24.5 mg/L, corresponding to 12 mg TOC/L. The organic carbon content was based on the molecular formula. The Theoretical CO2 production (ThCO2) of Disperse Brown 27 was calculated to be 1.81 mg CO2/mg.

The study consisted of six bottles:

- 2 inoculum blanks (no test item),

- 2 test bottles (Disperse Brown 27),

- 1 positive control (sodium acetate) and

- 1 toxicity control (Disperse Brown 27 plus sodium acetate).

Since Disperse Brown 27 was not sufficiently soluble to allow preparation of an aqueous solution at a concentration of 1 g/L, weighed amounts were added to the 2-litres test bottles containing medium with microbial organisms and mineral components. To this end, 10 mL of Milli-RO water was added to each weighing bottle containing the test item. After vigorous mixing (vortex) the resulting suspension was added quantitatively to the test medium. The test solutions were continuously stirred during the test to ensure optimal contact between the test item and test organisms. Furthermore, the test medium was daily swirled around, since

the test item tended to float on the water surface. Test duration was 28 days (last CO2 -measurement on day 29).

The relative biodegradation values calculated from the measurements performed during the test period revealed no significant biodegradation of Disperse Brown 27.

In the toxicity control, Disperse Brown 27 was found not to inhibit microbial activity. Since all criteria for acceptability of the test were met, this study was considered to be valid. Disperse Brown 27 was designated as not readily biodegradable.

Description of key information

In the toxicity control, Disperse Brown 27 was found not to inhibit microbial activity. Since all criteria for acceptability of the test were met, this study was considered to be valid. Disperse Brown 27 was designated as not readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

In the toxicity control, Disperse Brown 27 was found not to inhibit microbial activity. Since all criteria for acceptability of the test were met, this study was considered to be valid. Disperse Brown 27 was designated as not readily biodegradable.