Reaction mass of trisodium [m[7-[[4'-[[6-benzamido-1-hydroxy-3-sulpho-2-naphthyl]azo]-3,3'-dihydroxy[1,1'-biphenyl]-4-yl]azo]-8-hydroxynaphthalene-1,6-disulphonato(7-)]]dicuprate(3-) and trisodium [m[4-[[4'-[[6-benzamido-1-hydroxy-3-sulpho-2-naphthyl]azo]-3,3'-dihydroxy[1,1'-biphenyl]-4-yl]azo]-3-hydroxynaphthalene-2,7-disulphonato(7-)]]dicuprate(3-)

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:

October 02nd, 1985

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Version / remarks:

4 April 1984

GLP compliance:

yes

Vehicle:

no

Details on test solutions:

The test solution 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.
- Pretreatment: the sludge was centrifuged and washed three times with drinking water.
- Preparation of inoculum for exposure: the sludge was suspended in water with a solids content of 4 g/l and - after the addition of 20 ml synthetic sewage per litre 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, 320m 560 and 1000 mg/l

Details on test conditions:

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

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

MEASURING APPARATUS
500 ml flat bottomed flask, totally filled with test solution.

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Duration:

3 h

Dose descriptor:

IC50

Effect conc.:

> 1 000 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): 5.8 mg/l

Rate of respiration inhibition

Concentration (mg/l)	Oxygen consumption (mg O2/l/min)	Inhibition (%)
Control 1	1.2	-
Control 2	1.087	-
Mean	1.143	0
Test item 100	1.045	8.6
Test item 180	1.105	3.3
Test item 320	1.000	12.5
Test item 560	1.061	7.2
Test item 1000	1.148	0

Conclusions:

IC50 (3h) > 1000 mg/l (nominal)

Executive summary:

The inhibitory effect of test item on the oxygen consumption of activated sludge from a sewage works treating predominantly domestic sewage. The inhibitory effect include the effect on respiration and was measured by a 500 ml flat bottomed flask, totally filled with test solution. The exposure time of the test substance on the activated sludge was 3 hours. The nominal concentrations of test item were 6100, 180, 320, 560 and 1000 mg/l.

At the applied test concentrations, the test substance showed no significant toxic effects to the activated sludge. The inhibition of respiration rate resulted to be 8.6, 3.3, 12.5, 7.2 and 0 % at 100, 180, 320, 560 and 1000 mg/l, respectively.

Conclusion

IC50 (3h) > 1000 mg/l (nominal)

Description of key information

IC50 (3h) > 1000 mg/l (nominal)

Key value for chemical safety assessment

EC50 for microorganisms:

1 000 mg/L

Additional information

The inhibitory effect of test item on the oxygen consumption of activated sludge from a sewage works treating predominantly domestic sewage. The test substance showed no significant toxic effects to the activated sludge. The inhibition of respiration rate resulted to be 8.6, 3.3, 12.5, 7.2 and 0 % at 100, 180, 320, 560 and 1000 mg/l, respectively.