Reaction products of disodium 3,5-diamino-2-[(2-sulfonatophenyl)diazenyl]benzoate and  diazotised sodium 2-[(4-aminophenyl)sulfonyl]ethyl sulfate

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:

Study initiation date - 07 February 2003; Experiment start date - 10 February 2003; Experiment end date - 12 February 2003; Study completion date - 14 March 2003.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Identity: FAT 40810/A
Batch: WP 6/02
Purity: approx. 75 %
Appearance: Solid, dark brownish powder
Expiration date: 12 December 2010
Storage: At room temperature at about 20 °C

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

Stock solution: 2.00 g test item were weighed, dissolved, homogenized, and made up to 1000 ml with tap water.
Test item concentration: To obtain the nominal test concentrations of: 26, 64, 160, 400, and 1000 mg test item/L the following volumes were taken from the stock solution: 1.3, 3.2, 8.0, 20, and 50 mL, added to respective test vessels, then filled up to 100 mL with tap water after adding 3.2 mL synthetic sewage feed and 40 mL sludge.

Test organisms (species):

activated sludge, domestic

Details on inoculum:

Test system: Activated sludge of a communal sewage treatment plant (ARA Therwil, Switzerland) collected on February 10, 2003.
Sludge pre-treatment: The inoculum was prepared two days before test began. The freshly collected activated sludge was washed 3 times with tap water. Subsequently the sludge was aerated. The day the test started, a sample of the activated sludge was taken to determine the dry weight of the suspended solids. The final concentrations of the inoculum was about 4.3 g/L suspended solids. The pH of the inoculum was 7.8.

Test type:

other: aerobic

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test temperature:

20 ± 2 °C

pH:

7.8 - 7.9

Nominal and measured concentrations:

Nominal: 26, 64, 160, 400, and 1000 mg/L of the test item
Nominal: 7.5, 15, and 30 mg/L of the reference item

Details on test conditions:

The respiration rate of an activated sludge fed with a standard amount of synthetic sewage feed was measured after a contact time of 3 hours. The respiration rate of the same activated sludge in the presence of various concentrations of the test item under otherwise identical conditions was also measured. The inhibitory effect of test item at a particular concentrations was expressed as a percentage of the mean respiration rates of two controls. If possible lC50 and IC20 were calculated from inhibition values at different concentrations.

Reference substance (positive control):

yes

Remarks:

3,5-dichlorphenol

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

Details on results:

At all applied test concentrations, the test item showed no significant toxic effects (%inhibition of the respiration rate <15%) to the activated sludge. Therefore, the lC50 and IC20 values were estimated as follows: IC50 (3h) of FAT 40810/A: >1000 mg/L and IC20 (3h) of FAT 40810/A: >1000 mg/L.
Oxygen-consumption measured throughout the test indicated no significant inhibitory effect up to the highest concentration tested.

Results with reference substance (positive control):

The reference item 3,5-dichlorphenol showed an IC50 of 11.5 mg/L and therefore showed the system to be valid and efficient.

Reported statistics and error estimates:

In absence of effects on the test substance no statistics was applied. For the reference substance results, the probit model was used.

Validity criteria fulfilled:

yes

Conclusions:

FAT 40810/A is not toxic to sludge bacteria (EC20 >1000 mg/L).

Executive summary:

The objective of this sduty was estimation of toxicity of FAT 40810/A to activated sludge containing micro-organisms. The test item was conducted in accordance with OECD test guideline 209 and EEC Part C, in a GLP-certified laboratory. The test item concentration was 26, 64, 160, 400 and 1000 mg/L of test item. 3,5 -dichlorophenol is used as reference item. At all applied test concentrations, the test item showed no significant toxic effects (% inhibition of the respiration rate <15 %) to the activated sludge. Therefore, the IC50 and IC20 values were estimated as follows: Test item IC50 (3h) >1000 mg/L, IC20(3h) >1000 mg/L. The reference item was IC50 (3h) = 11.5 mg/L.

Description of key information

FAT 40810/A sludge bacteria toxicity: IC20(3h) >1000 mg/L

Key value for chemical safety assessment

EC50 for microorganisms:

1 000 mg/L

EC10 or NOEC for microorganisms:

1 000 mg/L

Additional information

The objective of this study was estimation of toxicity of FAT 40810/A to activated sludge containing micro-organisms. The test item was conducted in accordance with OECD test guideline 209 and EEC Part C, in a GLP-certified laboratory. The test item concentration was 26, 64, 160, 400 and 1000 mg/L of test item. 3,5 -dichlorophenol is used as reference item. At all applied test concentrations, the test item showed no significant toxic effects (% inhibition of the respiration rate <15 %) to the activated sludge. Therefore, the IC50 and IC20 values were estimated as follows: Test item IC50 (3h) >1000 mg/L, IC20(3h) >1000 mg/L. The reference item was IC50 (3h) = 11.5 mg/L.