5',5'''-[ethylenebis(p-phenyleneazo)]bis[1',2'-dihydro-6'-hydroxy-4'-methyl-2'-oxo-1,3'-bipyridinium] dilactate

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

Range finding test: 15th February, 1991. Main test: 21st February, 1991.

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Justification for type of information:

The test substance is the acid form of the substance under registration; justification for Read Across is detailed in the IUCLID section 13.

Reason / purpose for cross-reference:

read-across source

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

GLP compliance:

not specified

Details on test solutions:

Test item has been direct dispersion in water.

Test organisms (species):

activated sludge

Details on inoculum:

- Source: the aeration Stage of Severn Trent PLC Sewage Treatment Plant, Belper, Derbyshire.
- Preparation: the sample was maintained at 21 °C with continuous aeration and used on the day of collection. The pH was buffered to pH 7.0 with sodium hydroxide solution and the suspended solids level adjusted to 3.9 g/l prior to use.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

3 h

Nominal and measured concentrations:

Range-finding test: 1.0, 10, 100, 1000 mg/l (nominal)
Main test: 1000 mg/l (nominal)

Details on test conditions:

TEST SYSTEM
- No. of vessels per concentration: one replicate per concentration in the range-finding test; three replicated in the main test.
- No. of vessels per control: two replicates

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Details on results:

MAIN TEST
Only slight effects were recorded: the percentage of the respiration inhibition ranges from 8 to 17.
Variation between the controls: ± 2 %

RANGE-FINDING TEST
Variation between the controls: 0 %

Results with reference substance (positive control):

EC50 (3h): 11.5 mg/l

Main test

Concentration (mg/l )	O2 consumption rates mg/O2/l/min	% inhibition
Control	0.61	-
Control	0.59	-
Test item 1000	0.52	13
Test item 1000	0.5	17
Test item 1000	0.55	8
3,5-dichlorophenol 3.2	0.61	<2>
3,5-dichlorophenol 32	0.06	90

<increase>

Range-finding test

Concentration (mg/l )	O2 consumption rates mg/O2/l/min	% inhibition
Control	0.41	-
Control	0.41	-
Test item 1.0	0.42	<2>
Test item 10	0.35	15
Test item 100	0.39	5
Test item 1000	0.34	17
3,5-dichlorophenol 3.2	0.38	7
3,5-dichlorophenol 32	0.01	98

<increase>

Conclusions:

EC50 (3h) > 1000 mg/l (nominal)

Executive summary:

Activated sludge respiration inhibition test has been performed on test item. A range-finding investigation was conducted at the nominal concentrations of 1.0, 10, 100 and 1000 mg/l. The main test was conducted at the nominal concentration of 1000 mg/l; three replicates were assayed. Blank control and reference item, 3,5-dichlorophenol, have also been tested.

Only slight effects were recorded: the percentage of the respiration inhibition ranges from 8 to 17. The EC50 after 3 hours of contact time has been indicate as higher than 1000 mg/l.

Conclusion

EC50 (3h) > 1000 mg/l (nominal)

Description of key information

Not harmful/toxic to microorganisms. EC50 (3h) > 1000 mg/l (nominal)

Additional information

There are no information about the toxicity potential to microorganisms of Basic Yellow 094, thus the available information on the structural analogue Similar Substance 01 have been taken into consideration. Similar Substance 01 is the acid form of Basic Yellow 094; the read across approach can be considered as appropriate and suitable to assess the property under investigation (details about the approach are reported into the IUCLID section 13).

Activated sludge respiration inhibition test has been performed on Similar Substane 01. On the basis of the outcomes of the range-finding investigation, the main test was conducted at the nominal concentration of 1000 mg/l. Only slight effects were recorded: the percentage of the respiration inhibition range from 8 to 17. The EC50 after 3 hours of contact time has been indicate as higher than 1000 mg/l.