4-[(2,5-dichlorophenyl)azo]-N-(2,3-dihydro-2-oxo-1H-benzimidazol-5-yl)-3-hydroxynaphthalene-2-carboxamide

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 18 AUG 2005 to 19 AUG 2005

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study performed according to relevant guideline and compliant to GLP

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

yes

Remarks:

Reference substance copper (II) sulphate pentahydrate instead of the prescribed 3,5-dichlorophenol.

GLP compliance:

yes (incl. QA statement)

Remarks:

GLP according to German Chemikaliengesetzt and Directive 88/320/EEC

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

Test concentrations 1000 mg/L
Pretreatment The test item was weighed out directly into an Erlenmeyer flask, filled with 250 mL autoclaved tap water and stirred for 24 h.
Dispersion treatment Agitation
CONTROL 2 control samples without test item were included, one at the beginning and one at the end of the test.

Test organisms (species):

activated sludge, domestic

Details on inoculum:

Non adapted activated sludge from the municipal sewage treatment plant of D-31157 Sarstedt
The sludge was washed twice with autoclaved tap water and diluted corresponding to a dry weight of 4.0 g/L ± 10 %.
Date of receipt: 2005-08-18
Dry sludge concentration: 4.15 g/L

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

3 h

Test temperature:

20.6 deg C

pH:

6.75 for the activated sludge

Nominal and measured concentrations:

Treatment: 1000 mg/L nominal concentration
Control (1 and 2): 0 mg/L

Details on test conditions:

REFERENCE ITEM Copper (II) sulphate pentahydrate p.a. MERCK
CAS RN 7758-99-8
Lot A265990
Purity 99.9 %
Expiry date 2005-11-30
Test concentrations 58 - 100 - 180 mg/L
Range of validity (EC50) 51 - 157 mg/L

TEST METHOD Static
Test duration 3 h
Replicates One per concentration and two per control
Test vessels 500 mL Erlenmeyer flasks, DIN 12380
Volume of the study medium 500 mL

Nutrient solution Synthetic waste water according to OECD 209

Application:
200 mL inoculum
16 mL synthetic waste water
284 mL autoclaved tap water
Test item concentration (directly weighing)

Aeration Permanent

The pH-value of the activated sludge was measured prior to testing and the temperature in the measuring cell once during the measurement.
The oxygen depletion of the control, reference and test item was measured after 3 h incubation by means of oximeter and recorded for at least 3 minutes on a flat bed recorder.
Room temperature: continuously recorded by a hgrothermograph

The study was carried out with a limit test concentration of 1000 mg/L. 2 control replicates without test item were included.
A fresh sample of activated sludge taken from the sewage plant Sarstedt was used for the test procedure. It was washed twice and diluted with autoclaved tap water to a dry sludge concentration of 4.0 g/L +/- 10 %.
The reference item was tested in three concentrations within the concentration range 58 - 180 mg/L with a dilution factor of 1.8. The respiration rates of all samples were determined subsequently to an incubation period of 3 h.

Reference substance (positive control):

yes

Remarks:

Copper (II) sulphate pentahydrate, CAS RN 7758-99-8

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

Remarks:

respiration rate

Details on results:

After stirring for 24 h the test item was mostly dispersed. Only part of the test item floated on the surface and stuck to the side of the Erlenmeyer flask. The test item foamed slightly.
For details see "Any other information on results incl. tables"!

Results with reference substance (positive control):

In the reference test the EC50 -value for copper(II)-sulphate-pentahydrate was determined by probit analysis with:
EC50 = 99 mg/L
This is in the recommended confidence range of 51 - 157 mg/L.

Reported statistics and error estimates:

The EC50-value of the reference item was calculated with probit analysis using software SIGMAPLOT (Windows) rel. 8.02, 2002, SPSS CORPORATION. Probit values were taken from WEBER (1986). Confidence intervals were calculated according to a standard procedure (BREITIG & TÜMPLING 1982).

Table 1: Respiration Rates and Inhibition of Respiration of Test and Reference Item Concentrations

	Concentration [mg/L]	Respiration rate [mgO2/L.h]	Inhibition [%]
Test item	1000	30.0	7
Control 1	-	34.4	-
Control 2	-	30.4	-
Reference item	180	6.8	79
	100	16.8	48
	58	24.0	26

Difference of the control respiration rates: 12 %

Validity criteria fulfilled:

yes

Conclusions:

In a respiration inhibition test with acitvated municipial sludge (OECD 209) the following effect concentration was determined for the submission substance
EC50 (3h) > 1000 mg/L (nominal concentration)

Executive summary:

A Respiration Inhibition Test with activated sludge according to OECD Guideline No. 209 was performed with the test item. Test system was activated sludge of the municipal treatment plant of D-31157 Sarstedt. The test was performed under static conditions with the nominal limit concentration 1000 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. No inhibition was observed at the tested limit concentration.

In order to check the activity of the test system and the test conditions a reference test was carried out with copper-(II)-sulphate-pentahydrate as reference item and the reference toxicity was determined. The EC50-value for the reference item was 99 mg/L.

Validity criteria of the test guideline were fulfilled.

The test item is not toxic at concentrations <= 1000 mg/L to activated sludge of a municipal sewage treatment plant.

Reference 2

Endpoint:

activated sludge respiration inhibition testing

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

see Section 13 for the attached Justification for read-across report

Reason / purpose for cross-reference:

read-across source

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

Remarks:

respiration rate

Validity criteria fulfilled:

yes

Conclusions:

In a respiration inhibition test with activated municipial sludge (OECD 209) the following effect concentration was determined for the submission substance
EC50 (3h) > 1000 mg/L (nominal concentration)

Executive summary:

A Respiration Inhibition Test with activated sludge according to OECD Guideline No. 209 was performed with the test item. Test system was activated sludge of the municipal treatment plant of D-31157 Sarstedt. The test was performed under static conditions with the nominal limit concentration 1000 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. No inhibition was observed at the tested limit concentration.

In order to check the activity of the test system and the test conditions a reference test was carried out with copper-(II)-sulphate-pentahydrate as reference item and the reference toxicity was determined. The EC50-value for the reference item was 99 mg/L.

Validity criteria of the test guideline were fulfilled.

The test item is not toxic at concentrations <= 1000 mg/L to activated sludge of a municipal sewage treatment plant.

Description of key information

RA from PR176

A Respiration Inhibition Test with activated sludge according to OECD Guideline No. 209 was performed with the test item. No inhibition was observed at the tested limit concentration.

In a respiration inhibition test with activated municipial sludge (OECD 209) the following effect concentration was determined for the substance

EC50 (3h) > 1000 mg/L (nominal concentration)