Copper, diammine[5,5'-bi-1H-tetrazolato(2-)-kN1, kN1']

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:

2016

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Lack of analytical determination of the substance

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test (Carbon and Ammonium Oxidation))

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Certificate is incuded in the report

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

Test mixtures were prepared by adding 16 mL synthetic sewage to the appropriate amounts of test item (directly weighed an incorporated into the test vessel) and water followed by the addition of inoculum to obtain a final volume of 500 mL containing 1.5 g/L of suspended solids and different nominal concentrations of the test item.

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

The inoculum was prepared from activated sludge sampled the 5 December 2016, in the aeration tank treatment plant receiving predominantly domestic sewage (Montataire - (60) France). After settling, the supernatant of activated sludge was discarded and the sludge re-suspended in chlorine-free tap water. The wash-water was again removed after settling of sludge and activated sludge were re-suspended in chlorine-free tap water.The inoculum was continuously aerated and 50 mL of synthetic sewage feed/L activated sludge were added each day until use.Test carried out 6 December 2016:dry matter of inoculum: 3.9 g/LpH: 7.4192.3 mL of inoculum were added per test flask corresponding to a concentration of suspended solids (SS) in the test mixture of 1.5 g/L

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Hardness:

Not available

Test temperature:

between 18.5 and 21.5°C

pH:

Between 7.1 and 7.7Between 7.3 and 8.0 (test with ATU)

Salinity:

Not available

Conductivity:

Not available

Nominal and measured concentrations:

1.0 – 10 – 100 and 1000 mg/L (nominal concentrations)

Details on test conditions:

- Vessel: 1 litre glass beakers- Inoculum: prepared from activated sludge- Dilution water: deionised water- Medium: synthetic sewage feed- Total volume of mixtures: 500 mL- Air supply: clean, oil-free. Air flow 0.5 to 1 litre/ min.

Reference substance (positive control):

yes

Remarks:

3.5-dichlorophenol

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (total fraction)

Remarks:

Available information has shown that the test item is not soluble in water.

Basis for effect:

inhibition of total respiration

Remarks on result:

other: Available information has shown that the test item is not soluble in water.

Details on results:

The results show that under the test conditions the test item: CuDABT has no significant toxic effect on respiration of activated sludge at concentrations 1.0 and 10.0 mg/L and approximately 10% of inhibition at 100 mg/L for total respiration after a contact time of 3 hours.Significant inhibitory effects have been observed at the highest concentration tested: 1000 mg/L.No oxygen consumption was observed for abiotic controls during this test, showing a lack of reducing properties of the test item.

Results with reference substance (positive control):

3,5–DCP: 3.13 mg/L: 34.5% of inhibition10.0 mg/L: 48.3% of inhibition32.0 mg/L: 86.2% of inhibitionThe EC50 3,5-DCP, after a contact time of 3 hours, was graphically determined between 10 and 20 mg/L.

  Specific inhibitor of nitrification: N-allylthiourea (ATU)

 

Identification	Q1 (mg/L)	Q2 (mg/L)	Dt	RH mg O2/Lh	RHS mg O2/gh	IH (%)	pH
							T0	T3h
Blank control 1	6.9	5.3	4	24.0	16.0	/	7.3	8.0
Blank control 2	6.2	4.1	4	31.5	21.0		7.3	8.0
Blank controls	Mean			27.8	18.5	/
	Coefficient of variation (%)			19.1
CuDABT 1.0 mg/L	6.1	4.4	4	25.5	17.0	8.3	7.3	7.9
CuDABT 10.0 mg/L	6.0	4.1	4	28.5	19.0	/	7.3	8.0
CuDABT 100 mg/L	6.1	4.1	4	30.0	20.0	/	7.4	7.9
CuDABT 1000 mg/L	6.3	5.0	4	19.5	13.0	29.9	7.3	7.9

 The test series carried out with the N-allylthiourea (ATU) showed that the oxygen uptake rates were lower for the blank controls and for the test item in the presence of ATU compared to in absence of ATU. This difference between the rates therefore indicates that there is an oxygen uptake due to the nitrification. Nevertheless, the inhibition percentages obtained during this study, whether for total respiration or for heterotrophic respiration, are very similar and less than 50% of inhibitory effect for all test concentrations.

Validity criteria fulfilled:

yes

Remarks:

The blank controls oxygen uptake rate remained above 20 mg O2/g h during the test and the coefficient of variation did not exceed 30% at the end of the test. EC50 (3 hours) of 3,5-dichlorophenol were in the range 2 mg/L and 25 mg/L.

Conclusions:

In the test conditions, an EC50 greater than of 1000 mg/L (nominal concentration) has been found for the test item CuDABT, after a contact time of 3 hours.

Executive summary:

The total respiration rate of an activated sludge fed with a standard amount of synthetic sewage feed is 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: CuDABT under otherwise identical conditions is also measured. The inhibitory effect of the test item at a particular concentration is expressed as a percentage of the mean respiration rates of the controls.

In the test conditions, no oxygen consumption was observed for abiotic controls during this range-finding test, showing a lack of reducing properties of the test item and an EC50 greater than of 1000 mg/L (nominal concentration) after a contact time of 3 hours.

Description of key information

In the test conditions, an EC50 greater than of 1000 mg/L (nominal concentration, available information has shown that the test item is not soluble in water) has been found for the test item CuDABT, after a contact time of 3 hours.

Key value for chemical safety assessment

EC50 for microorganisms:

1 000 mg/L