Nickel, 5-[2-(2-hydroxy-3,7-disulfo-1-naphthalenyl)diazenyl]-1H-1,2,4-triazole-3-carboxylate sodium complexes

Toxicity to microorganisms

Administrative data

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Study test phase 2002-11-01. Study report date 2002-11-21

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Meets the criteria for classification as Reliable without restriction according to Klimisch et al (1997)

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2002

Report date:

2002

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

-

EC Number:

443-510-2

EC Name:

-

Cas Number:

738587-10-5

Molecular formula:

C26H14N10Ni2O18S4 as free acid

IUPAC Name:

dinickel(2+) sodium 3-carboxy-5-[(1E)-2-(7-oxido-2,6-disulfonaphthalen-1-yl)diazen-1-yl]-1H-1,2,4-triazol-1-ide 3-carboxy-5-[(1E)-2-(7-oxido-2-sulfo-6-sulfonatonaphthalen-1-yl)diazen-1-yl]-1H-1,2,4-triazol-1-ide

Sampling and analysis

Analytical monitoring:

no

Test solutions

Vehicle:

no

Details on test solutions:

A nominal 500 mg/L stock solution of the test material was prepared in deionised water. The pH was measured and adjusted to be within the range 7 +/-1 using 2M HCl. Test solutions were prepared by the addition of a known volume of this stock solution to a total volume of 500ml aerated dechlorinated water, synthetic sewage and activated sludge. Nominal concentrations of 1.0, 3.2, 10, 32 and 100 mg/L of test substance were prepared. Five flasks containing the reference substance at nominal concentrations of 1.0, 3.2, 10, 32 and 100 mg/L were also prepared.

Test organisms

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

Activated sludge was obtained from Buckland Sewage Treatment Works, Newton Abbot, Devon, UK 1 day prior to commencement of the test. On return to the laboratory the activated sludge was settled and the concentrated sludge washed with aerated dechlorinated water. The washed settled sludge was fed with 50ml of OECD synthetic sewage feed per litre of sludge per day and aerated at room temperature until it was used in the test.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test conditions

Test temperature:

20 +/-2 degree C

pH:

7.4-8.2

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 100 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:

NOEC

Effect conc.:

100 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: EC20

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Effect concentrations 4

Duration:

3 h

Dose descriptor:

other: EC80

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Details on results:

The respiration rates in the two control flasks were within 15% of each other. Therefore, the mean control respiration was used in calculation of the percentage inhibition.
In the test flasks dosed with the test substance <10% respiration inhibition was observed in all the tested concentrations.

Results with reference substance (positive control):

- Results with reference substance valid.
- Relevant effect levels: 3h EC50 for DCP was determined to be 13 mg/L which is within the normal range of 2 to 30 mg/L. This indicates that the sludge was responding normally and confirms the viability of the sludge organisms.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

In the test flasks dosed with the test substance, <10% respiration inhibition was observed at all the tested concentrations. The 3hour EC50 for the test substance was determined to be >100 mg/L. The 3hour NOEC was determined to be 100 mg/L. Therefore it is concluded that 100mg/L of the test substance did not have a toxic effect on the respiration rate of activated sludge micro-organisms in this study.

Executive summary:

Introduction

This study was performed to assess the effect of the test substance on the respiration rate of activated sludge micro-organisms typical of those found in domestic sewage treatment using a respirometric test. The method was designed to be compatibile with the following guideline:

OECD Guidelines for the Testing of Chemicals (1993). Test Guideline 209, Activated Sludge, Respiration Inhibition Test. (Adopted 4 April 1984).

Results

After 3 hours <10% respiration inhibition was observed in all the test flasks dosed with the test substance.

Conclusion

The 3 hour EC50 was >100 mg/L. The 3 hour NOEC was determined to be 100 mg/L. Therefore it is concluded that 100mg/L of the test substance did not have a toxic effect on the respiration rate of activated sludge micro-organisms in this study.