Copper, diamminebis(nitrato-kO)

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)

Deviations:

yes

Remarks:

without impact on the study conclusion

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Copper, diamminebis(nitrato-kO)

EC Number:

604-942-9

Cas Number:

15414-04-7

Molecular formula:

CuH6N4O6

IUPAC Name:

Copper, diamminebis(nitrato-kO)

Sampling and analysis

Analytical monitoring:

yes

Test solutions

Vehicle:

no

Details on test solutions:

As the test item is not readily soluble and unstable in water, a stock solution was prepared in the test medium (nominal concentration: 50 mg/L), in the dark under magnetic stirring, 24 hours before initiating the algal growth inhibition test.
After membrane filtration (nylon membrane filter, 0.45 μm pore size, 90 mm diameter), the stock solution was diluted in the test medium to achieve the required test concentrations. Part of the copper was undissolved and was removed by filtration.

Test organisms

Test organisms (species):

Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)

Details on test organisms:

Pseudokirchneriella subcapitata, green algae belonging to the order of Chlorococcales; strain CCAP 278/4

Study design

Test type:

not specified

Water media type:

other: sterile deionised water

Limit test:

no

Total exposure duration:

72 h

Test conditions

Hardness:

not specified

Test temperature:

21.0 -23.8 (and less than 1 hour between 19.7 and 21°C)

pH:

7.7 to 8.6 (at t=72h)

Dissolved oxygen:

not specified

Salinity:

not specified

Conductivity:

not specified

Nominal and measured concentrations:

1.875; 3.75; 7.50; 15.0; 30.0 mg/L (initial nominal concentrations)

Details on test conditions:

Vessels: 250 mL conical flasks with air permeable stoppers filled with 100 mL of test solutions

Number of replicates:
-Algal growth:
6 for control conditions, 3 per concentration, 1 per concentration, without algae (blank control)
-Analysis:
2 per concentration for analysis (with and without algae) for each sampling time

Incubation illumination: 60 - 86 μmol m 2s-1 (corresponding to 2000-2800 Lux)

Agitation: Orbital shaking 125 rpm

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Results and discussion

Effect concentrations

Effect concentrations 1

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

1.875 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 2

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

8.71 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 3

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

2.98 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

The analyses performed have shown that dissolved copper concentrations, even if they were low, were in a range that may affect the growth of Pseudokirchneriella subcapitata. It was therefore impossible to identify which compound of the test item “MNP-363” was responsible for the observed effects.
Consequently, NOEC and ECx values have been expressed in concentrations of the mixture of copper and guanidine:
- NOEC: 1.875 mg/L (nominal concentration), corresponding to an exposure to a mixture of 0.00629 mg/L dissolved copper and 0.45 mg/L guanidine
- ErC10 72 h = 2.98 mg/L (2.31 – 3.65) (nominal concentration), corresponding to an exposure to a mixture of 0.00933 mg/L dissolved copper and 0.73 mg/L guanidine.
- ErC50 72 h = 8.71 mg/L (7.99 – 9.66) (nominal concentration), corresponding to an exposure to a mixture of 0.021 mg/L dissolved copper and 2.07 mg/L guanidine.

Results with reference substance (positive control):

Sensitivity of the strain of Pseudokirchneriella subcapitata was checked using potassium dichromate.
The test carried out gave the following result: ErC50 72 h: 1.15 mg/L

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The analyses performed have shown that dissolved copper concentrations, even if they were low, were in a range that may affect the growth of Pseudokirchneriella subcapitata. It was therefore impossible to identify which compound of the test item “MNP-363” was responsible for the observed effects.
Consequently, NOEC and ECx values have been expressed in concentrations of the mixture of copper and guanidine:

The substance gave the following results:
- NOEC: 1.875 mg/L (nominal concentration), corresponding to an exposure to a mixture of 0.00629 mg/L dissolved copper and 0.45 mg/L guanidine
- ErC10 72 h = 2.98 mg/L (2.31 – 3.65) (nominal concentration), corresponding to an exposure to a mixture of 0.00933 mg/L dissolved copper and 0.73 mg/L guanidine.
- ErC50 72 h = 8.71 mg/L (7.99 – 9.66) (nominal concentration), corresponding to an exposure to a mixture of 0.021 mg/L dissolved copper and 2.07 mg/L guanidine.