Tetracopper hexahydroxide sulphate

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

09 April 2018 - 03 July 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)

Deviations:

no

Principles of method if other than guideline:

Not applicable

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Details on inoculum:

- Source of activated sludge: microorganisms from a domestic waste water treatment plant was supplied by the sewage treatment plant Rossdorf, Germany,
- Conditioning: The aerobic activated sludge used for this study was deposited for 60 min, washed by centrifugation and the supernatant liquid phase was decanted. The solid was re-suspended in test water and centrifuged again. This process was repeated three times.
- Concentration of sludge: Stock suspension of 3.5 g dry material per litre (final sludge concentration in test flasks: 28.7 mg sludge/L)

Duration of test (contact time):

ca. 28 d

Initial conc.:

25.1 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of test water:
Analytical grade salts were added to pure water to prepare the following stock solutions:
a) 8.5 g KH2PO4, 21.75 g K2HPO4, 33.4 g Na2HPO4 x 2H2O, 0.5 g NH4Cl filled up with pure water to 1000 mL volume; The pH value was 7.4.
b) 11.25 g MgSO4 x 7H2O filled with pure water to 500 mL volume
c) 18.2 g CaCl2 x 2 H2O filled with pure water to 500 ml volume
d) 0.125 g FeCl3 x6H2O filled with pure water to 500 mL volume. One drop of HCl was added to d) to prevent preciptation of iron hydroxide.

50 mL of stock solution a) and 5 mL of the stock solutions b) to d) were combined and filled up to a final volume of 5000 mL with pure water.

The pH was adjusted to pH 7.4 with NaOH solution.

- Temperature: 22 ± 1 °C
- Light Conditions: Darkness
- pH value of test solutions: 7.5 (start of test), 7.5 to 7.6 (end of test)

TEST SYSTEM
- Type and size: Manometric Test system with test flasks containing a volume of 500 mL.
- Number of culture flasks/concentration: 2 flasks of test substances at a concentration of 25.1 mg per flask. An inoculum control was ran in duplicate with a procedure control, abiotic control and toxicity control.
- Reference substance: sodium benzoate

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes
- Abiotic sterile control: Yes - poisoned with CuSO4 (stock solution of 1g/L)
- Toxicity control: Yes

Reference substance:

benzoic acid, sodium salt

Preliminary study:

Not performed

Key result

Parameter:

% degradation (O2 consumption)

Value:

0

St. dev.:

0

Sampling time:

10 d

Remarks on result:

not readily biodegradable based on QSAR/QSPR prediction

Key result

Parameter:

% degradation (O2 consumption)

Value:

0

St. dev.:

0

Sampling time:

28 d

Remarks on result:

not readily biodegradable based on QSAR/QSPR prediction

Details on results:

Biodegradation of Tribasic Copper Sulphate: The biodegradation was followed by the oxygen uptake of the microorganisms during exposure. The degradation rate of tribasic copper sulphate never reached 60% within the 10 day window or after 28 days and therefore can be considered as not biodegradable. The degradation rate remained at 0% throughout the test.

The difference between the duplicate values for the degradation of the test item was less than 20%. The difference of duplicate values at day 28 differed by 0%. The validity criterion was therefore fulfilled.

Results with reference substance:

The reference item, sodium benzoate was sufficiently degraded to 78% after 14 days and to 81% after 28 days of incubation confirming the suitability of the aerobic activated sludge inoculum used.

Biodegradation of toxicity control:  In the toxicity control which contained both, the test item and the reference item, 77% biodegradation was noted within 14 days and 83% (ThODNH4) biodegradation after 28 days of incubation. The test item can be assumed to be not inhibitory to the aerobic activated sludge microorganisms because degradation was >25% within 14 days.

The pH value of the test item flasks at the end of the test was 7.5 and therefore within the range of pH 6.0 to 8.5 as required by the guideline.

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

The degradation rate of tribasic copper sulphate never reached 60% within the 10 day window or after 28 days. All validity criteria were met in the study. Therefore, tribasic copper sulphate is considered to be not readily biodegradable.

Executive summary:

The biodegradability of tribasic copper sulphate was determined by a study complying with EC Method C.4 -D and OECD 301 F. The test item was tested in a manometric respirometry test over a period of 28 days. The biodegradation was followed by the oxygen uptake of the microorganisms during exposure.

The degradation rate of tribasic copper sulphate never reached 60% within the 10 day window or after 28 days.  The reference item, sodium benzoate was sufficiently degraded to 78% after 14 days and to 81% after 28 days of incubation confirming the suitability of the aerobic activated sludge inoculum used. In the toxicity control which contained both, the test item and the reference item, 77% biodegradation was noted within 14 days and 83% (ThODNH₄) biodegradation after 28 days of incubation. The test item can be assumed to be not inhibitory to the aerobic activated sludge microorganisms because degradation was >25% within 14 days.

Overall, from the results obtained, it can be concluded that tribasic copper sulphate is considered to be not readily biodegradable.  

Description of key information

The degradation rate of tribasic copper sulphate never reached 60% within the 10 day window or after 28 days therefore, tribasic copper sulphate is considered to be not readily biodegradable.  

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Type of water:

freshwater