4-benzoylbenzene-1,2,3-triyl tris(6-diazo-5,6-dihydro-5-oxonaphthalene-1-sulphonate)

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:

2019

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 (Carbon and Ammonium Oxidation))

GLP compliance:

yes

Analytical monitoring:

yes

Vehicle:

no

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

Municipal sewage treatment plant of 31137 Hildesheim, Germany

Test type:

static

Water media type:

other: synthetic waste water

Remarks:

according to OECD 209

Limit test:

yes

Total exposure duration:

3 h

Test temperature:

nominal 18 - 22 °C, actually measured 19.6 °C

pH:

The pH value of the activated sludge was determined prior to test start. The pH value of the synthetic waste water was determined prior to use and adjustment to 7.5 +/- 0.5 was not necessary.

Dissolved oxygen:

After 3 h incubation, the oxygen concentration of each control, reference item and test item replicate was determined by means of oximeter every 5 seconds after transferring the solution to the measuring chamber and the oxygen depletion was recorded for at least 5 minutes with the software PreSens Measurement Studio 2.

Details on test conditions:

Preparation of the Test Vessels:
Based on the results of the preliminary test it was concluded that the heterotrophic respiration as well as the nitrification are not inhibited. Therefore, the definitive study was carried out with the concentration of 1000 mg a.i./L in 3 replicates (limit test to determine the NOEC). The concentration was weighed out directly in Erlenmeyer flasks and stirred overnight.
Triplicates of the control without test item were included at the beginning and at the end of the test.
The reference item was tested with three concentrations within the concentration range 58 - 180 mg/L and a dilution factor of approx. 1.8.
A fresh sample of activated sludge taken from the sewage plant Hildesheim was used for the test procedure. It was washed twice and adjusted with chlorine free tap water to a dry sludge concentration of 3.0 g/L +/- 10 %.
The oxygen uptake rates of all samples were determined following an incubation period of 3 h.

Reference substance (positive control):

yes

Remarks:

Copper (II) sulphate pentahydrate p.a.

Key result

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

>= 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks on result:

other:

Remarks:

based on test item concentration

From the oxygen depletion the oxygen uptake rates were calculated in mg O2/L * h, additionally the specific respiration rates based on the dry sludge concentration were calculated in mg O2/g * h. The inhibition of the oxygen uptake rates of the test item concentrations in % was calculated in comparison to the oxygen uptake rates of the control. The results are listed in Table 3 to Table 4.

Table 3: Oxygen Uptake Rates of the Control Replicates

	Repl.	Oxygen Concentration* [mg/O2/L]	Oxygen Uptake Rate R [mg O2/(L x h)]	Specific Respiration Rate Rs [mg O2/gxh]
	1 2 3 4 5 6	7.18 7.24 7.44 7.19 7.52 7.17	27.0 29.3 29.3 32.7 34.0 33.9	18.6 20.2 20.2 22.6 23.4 23.4
	Mean value		31.0	21.4
	Standard deviation		2.65
	CV [%]		8.55

*) determined at start of the measurement

Repl. = Replicate

CV = Coefficient of variation

Table 4: Oxygen Uptake Rates and Inhibition of the Respiration of the Test Item Concentration

Test item Concentration [mg a.i./L]	Repl.	Oxygen Concentration* [mg O2/L]	Oxygen Uptake Rate R [mg O2/(Lxh)]	Inhibition [%]	Mean Inhibition [%]
1000	1 2 3	5.59 6.19 5.19	30.8 30.7 30.5	1 1 2	1

*) determined at start of the measurement

Repl. = Replicate

In the reference test the EC50 value for copper (II) sulphate pentahydrate was determined with EC50 = 105 mg/L, 95 % Confidence Interval = 99.1 - 111 mg/L. This is the recommended range of validity of 53 - 155 mg/L.

Validity criteria fulfilled:

yes

Conclusions:

The NOEC of the test item is >= 1000 mg a.i./L.

Executive summary:

A study was performed according to OECD 209 guideline and GLP principles. In the study, the test item caused no inhibiting effects on activated sludge of a municipal sewage treatment plant at the limit test item concentration of 1000 mg a.i./L.

Description of key information

A study was performed according to OECD 209 guideline and GLP principles. In the study, the test item caused no inhibiting effects on activated sludge of a municipal sewage treatment plant at the limit test item concentration of 1000 mg a.i./L.