Trisodium 3-[[4-[[6-(anilino)-1-hydroxy-3-sulphonato-2-naphthyl]azo]-5-methoxy-o-tolyl]azo]naphthalene-1,5-disulphonate

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:

14 October 1998 to 15 October 1998

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

exposure duration 30 minutes

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Version / remarks:

version 1984

Deviations:

no

Qualifier:

equivalent or similar to guideline

Guideline:

EU Method C.11 (Biodegradation: Activated Sludge Respiration Inhibition Test)

Principles of method if other than guideline:

exposre time 30 minutes (deviation from the 2010 guideline)

GLP compliance:

no

Analytical monitoring:

not required

Vehicle:

no

Details on test solutions:

applied as such

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Name and location of sewage treatment plant where inoculum was collected: Wupperverband
- Pretreatment: none
- Initial biomass concentration: 320 mg/L

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

30 min

Remarks on exposure duration:

according to the current guidelines an exposure duration of 3 hours would have been required

Test temperature:

20 ± 2 °C

pH:

7.5-7.8

Nominal and measured concentrations:

Nominal 0, 100, 1000 and 10000 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: no data
- Aeration: yes continuously
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 2
- No. of vessels per abiotic control (replicates): 1
- Sludge concentration (weight of dry solids per volume): no data
- Biomass loading rate: 320 mg/L
TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: deionized water
- Particulate matter: NA
OTHER TEST CONDITIONS
- Adjustment of pH: none

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : oxygen consumption over 6-9 min period

TEST CONCENTRATIONS: 100, 1000 and 10000 mg/L

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Key result

Duration:

30 min

Dose descriptor:

EC50

Effect conc.:

10 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Key result

Duration:

30 min

Dose descriptor:

EC50

Effect conc.:

> 500 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

inhibition of total respiration

Details on results:

- Blank controls oxygen uptake rate: 26.6-27.0 mg/L h

Results with reference substance (positive control):

see table

Reported statistics and error estimates:

NA

Nominal Concentration (mg/L)		Initial O2 Reading (mg O2/L)	Measurement Period (minutes)	Final O2Reading (mg O2/L)	O2Consumption Rates (mg O2/L/hour)	% Inhibition
Control		5.4	6	2.7	27.0
		6.0	7	2.9	26.6
Test Item	100	5.5	6	2.7	28.0	0
	1000	6.4	8	2.7	28.0	0
	10000	6.5	8	2.8	27.8	0
3,5-dichlorophenol	5	6.4	8	3.1	24.8	7.5
	10	7.1	8	4.8	17.3	35.4
	20	8.2	8	6.9	9.8	67.4

 

Validity criteria fulfilled:

yes

Conclusions:

The 30min EC50 is > 500 mg/L based on the active ingredient

Executive summary:

In a study according to OECD 209 (with 30 min exposure period) the substance did not inhibit the respiration of sludge at concentrations up to 10000 mg/L. When corrected for the active ingredient the EC50 is >500 mg/L. The NOEC is 500 mg/L (based on a.i.)

Description of key information

In a study according to OECD 209 (with 30 min exposure period) the substance did not inhibit the respiration of sludge at concentrations up to 10000 mg/L (Bayer 1998). When corrected for the active ingredient the EC50 is >5000 mg/L. The NOEC is 5000 mg/L (based on a.i.)

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:

5 000 mg/L

Additional information

The substance did not inhibit the growth of sewage treatment microorganisms in a biodegradation test (Envigo 2017). This confirms that the substance is of low toxicity versus microorganisms.