Disodium [6-[(2-anilino-1-naphthyl)azo]-2,4-dinitrophenolato(2-)][3-hydroxy-4-[(2-hydroxy-1-naphthyl)azo]naphthalene-1-sulphonato(3-)]chromate(2-)

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

March 27th, 1985

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Version / remarks:

4 April 1984

GLP compliance:

yes

Details on test solutions:

The test solutions were prepared by adding the test material directly to the test water.

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Source: ARA Rhein, Pratteln, Switzerland.
- Treatment: the sludge is centrifuged and washed three times with drinking water, then suspended in water with a solids content of 4 g/I and - after the addition of 20 mI synthetic sewage per Iitre sludge suspension - aerated overnight at 20 °C.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test temperature:

20 ± 2 °C

Nominal and measured concentrations:

100, 180, 320, 560, 1000 and 1800 mg/l

Details on test conditions:

TEST SYSTEM
- Test vessel: 1000 mI glass beaker with 500 mI test solution.
- Aeration: 3 hours; air flow at 0.5 to 1 l/min.
- No. of vessels per concentration: 1 replicate.
- No. of vessels per control: 2 replicates.
- Sludge amount: 1.6 g/l

TEST MEDIUM / WATER PARAMETERS
- Source of dilution water: drinking water.
- Total hardness: about 180 mg CaCO3/I
- pH: 7.6 to 8.0.

EFFECT PARAMETERS MEASURED
The precentage inhibition of respiration was Plotted against concentration on logarithmic - probability paper. The EC50, EC20 and EC50 were calculated with normal statistical procedures (regression line).

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Duration:

3 h

Dose descriptor:

IC50

Effect conc.:

412 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Results with reference substance (positive control):

EC50 (3h): 7.7 mg/l

Rate of respiration inhibition

Concentration (mg/l)	Oxygen consumption (mg O2/l/min)	Inhibition (%)
Control 1	1.227	-
Control 2	1.206	-
Mean	1.216	0
100	0.966	20.5
180	0.900	26
320	0.737	39.4
560	0.653	46.3
1000	0.282	76.8
1800	0.136	88.8

Conclusions:

IC50 (3h): 412 mg/l

Executive summary:

The test material was tested in accordance with the OECD guideline 209. Test solutions were prepared by adding the test material directly to test water. Activated sludge from a sewage works treating predominantly domestic sewage.

The estimated IC50 for 3-hour exposure of activated sludge bacteria to test item was 412 mg/l.

Conclusion

IC50 (3h): 412 mg/l

Description of key information

IC50 (3h): 412 mg/l

Key value for chemical safety assessment

EC50 for microorganisms:

412 mg/L

Additional information

The test material was tested in accordance with the OECD guideline 209. Test solutions were prepared by adding the test material directly to the test water. Activated sludge from a sewage works treating predominantly domestic sewage. The estimated IC50 for 3-hour exposure of activated sludge bacteria to test item was 412 mg/l.

In addition, an old respiration rate test is available; it was performed in accordance with the ETAD recommended method no 103. Unfortunately, the reliability of the data cannot be judged because of the lacking of details about test material and testing procedures and conditions. The EC50 was indicated to be higher than 100 mg/l.

REFERENCE

See attachment