Disodium 7-[(4-amino-3-methoxyphenyl)azo]naphthalene-1,3-disulphonate

Toxicity to microorganisms

Administrative data

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study without detailed documentation

Remarks:

according to OECD 209, but limited documentation regarding the test material

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2001

Report date:

2001

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

Disodium 7-[(4-amino-3-methoxyphenyl)azo]naphthalene-1,3-disulphonate

EC Number:

265-529-3

EC Name:

Disodium 7-[(4-amino-3-methoxyphenyl)azo]naphthalene-1,3-disulphonate

Cas Number:

65151-26-0

Molecular formula:

C17H15N3O7S2.2Na

IUPAC Name:

disodium 7-[(4-amino-3-methoxyphenyl)diazenyl]naphthalene-1,3-disulfonate

Sampling and analysis

Analytical monitoring:

no

Test solutions

Vehicle:

no

Details on test solutions:

PREPARATION OF TEST SOLUTION

The test item was weighed out directly into the test vessels.
The following nominal concentrations of AGAMA Base were chosen: 125, 250, 500, 1000 and 2000 mg/L.

Test organisms

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Inoculum: activated sludge from the aeration tank of a municipal biological waste water treatment plant, not adapted and not pre-conditioned
- Name and location of sewage treatment plant where inoculum was collected: ARA Werdhoelzli, 8048 Zuerich, Switzerland
- Concentration: 1.6 g/L dry matter in the final mixture

Study design

Test type:

static

Limit test:

no

Total exposure duration:

3 h

Test conditions

Test temperature:

22 ± 0.5°C

pH:

7.5 ± 0.5

Nominal and measured concentrations:

Nominal concentrations: 125 mg/L, 250 mg/L, 500 mg/L, 1000 mg/L, 2000 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel:
- 1000 mL flasks
- fill volume: 500 mL
- Aeration: aerated by shaking 120 rpm
- No. of vessels per concentration (replicates): 1 (5 concentrations)
- No. of vessels per blank control (replicates): 2
- No. of vessels per reference substance control: 1 replicate sample (3 test concentrations)

TEST MEDIUM
The activated sludge was used immediately after sampling from the treatment plant without adaptation. Prior to the test, the sludge was washed twice with tap water. The test vessels contained 500 mL of final test medium anc activated sludge in an amount corresponding to 1.6 g/L dry matter in the final mixture.


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- the pH-value of the activated sludge was measured prior to testing and adjusted to pH 7.5 ± 0.5, if necessary
- the oxygen concentration was measured with a oxygen electrode (ORION 9708) inserted to a 300 mL BOD bottle and recorded for about 5 to 10 min

TEST CONCENTRATIONS
- Range finding study not conducted.
- Test concentrations: 125 mg/L, 250 mg/L, 500 mg/L, 1000 mg/L, 2000 mg/L (nominal)

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

3 h

Dose descriptor:

other: EC20

Effect conc.:

1 450 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Effect concentrations 2

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 2 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Effect concentrations 3

Duration:

3 h

Dose descriptor:

other: EC80

Effect conc.:

> 2 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Results with reference substance (positive control):

the EC50-value for the reference substance 3,5-dichlorophenol was estimated to be 2.5 mg/L which was low but in the range of 5 mg/L thus confirming suitability of activated sludge and test conditions.
The variation between the two blank controls was ± 2.3 %
Therfore, the test was considered valid.

Any other information on results incl. tables

Table 1: Respiration rates and inhibition of respiration of test and reference item concentrations

code	Concentration [mg/L]	Respiration Rate [mg O2/L x h]	Inhibition [%]
B1	control 0	76.0	-
B2	control 0	79.6	-
T1	125	76.7	1.5
T2	250	71.7	7.9
T3	500	71.7	7.9
T4	1000	64.0	17.8
T5	2000	59.6	23.5
R1	Reference 3	36.7	52.9
R2	Reference 10	21.5	72.4
R3	Reference 30	7.6	90.2

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

. The EC50 value was estimated to be > 2000 mg/L.

Executive summary:

A Respiration Inhibition Test was performed with activated sludge according to OECD Guideline No. 209. The test system was non-adapted activated sludge of a municipal treatment plant. The test was performed under static conditions with the nominal concentrations of 125, 250, 500, 1000 and 2000 mg/L. The respiration rates of control, reference and test item concentrations were measured after a contact time of three hours, and the inhibitory effects of the test and reference concentrations were determined in comparison to the control respiration rates.

In order to check the activity of the test system and the test conditions a reference test was carried out with 3,5 -dichlorophenol as reference item and the reference toxicity was estimated to be 2.5 mg/L. The variation between the two blank controls was ± 2.3 %.

Validity criteria of the test guideline were fulfilled.

At the applied test concentrations of 2000 and 1000 mg/L respiration inhibitions of 23 and 18 % respectively, were observed. At the other nominal concentrations the test item showed no significant toxic effects (< 15 % respiration inhibition) to activated sludge; the respiration rates were in the same range as determined for the two blank controls.

Based on these data the EC20 of the test item was calculated to be 1450 mg/L. The EC50 and EC80 values were estimated to be > 2000 mg/L.